Journal of the Korean Society for Precision Engineering

Development of a WA-DED Process for Low-angle Overhang Structures Using 3D Sand-printed Supports: Chang Young Choi, Hwi Jun Son, Seo Rim Park, Yeong Jae Kim, Young Tae Cho; J. Korean Soc. Precis. Eng. 2026;43(9):951-959.
Published online September 1, 2026; DOI: https://doi.org/10.7736/JKSPE.026.00044

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This study proposes a hybrid wire arc directed energy deposition (WA-DED) process that uses 3D sand-printed supports to overcome the limitations of low-angle overhang fabrication. WA-DED is a metal additive manufacturing process offering high deposition rates, cost efficiency, and suitability for large-scale components. However, because of its high heat input and molten pool instability, low-angle overhang and hollow structures remain difficult to fabricate, as the molten metal tends to collapse under gravity and thereby degrade geometric accuracy and surface quality. To address this issue, sand-printed supports were introduced. The supports provide tailored mechanical constraint and guide the solidification of the molten pool during deposition. Experiments were conducted to evaluate the feasibility of the proposed process at various overhang angles. The results show that the hybrid process markedly improves deposition stability and enables the fabrication of low-angle and curved overhang structures that conventional WA-DED cannot produce. These findings confirm the effectiveness of sand-supported WA-DED and highlight its potential for industrial applications requiring complex geometries, such as aerospace, marine, and energy components.

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Investigated New Thin Films based on Zn-doped MgO for Optoelectronic Devices: Nadjat Chaouch, Amira Sbaihi, Said Lakel, Abdelghani Lakel, Said Benramache; J. Korean Soc. Precis. Eng. 2026;43(9):987-996.
Published online September 1, 2026; DOI: https://doi.org/10.7736/JKSPE.026.00019

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In this work, Mg1-xZnxO thin films were deposited on glass substrates by the pneumatic spray technique at 450°C using a 0.15 M precursor solution of magnesium acetate and zinc acetate. The effect of Zn content (x = 0, 0.3, 0.5, and 0.7%) on the structural, morphological, optical, and electrical properties of the films was examined. XRD analysis showed that all films adopted a cubic MgO structure with diffraction peaks from the (111), (200), and (220) planes, and the crystallite size grew from 8.12 to 12.49 nm as the Zn content increased. SEM images indicated that moderate Zn incorporation improved film homogeneity, whereas higher Zn contents promoted agglomeration and surface roughening. The films transmitted well in the visible region, and the optical band gap widened from 3.56 to 3.93 eV at x = 0.3. The Urbach energy also rose with Zn content, reaching a maximum of 0.695 eV at x = 0.7, which indicates greater structural disorder. FTIR spectra confirmed that Zn incorporation modifies the chemical bonding network. The sheet resistance increased markedly with Zn content, demonstrating the strong influence of Zn doping on the optical and electrical properties of MgO thin films.

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Experimental Study on Porosity Behavior during DED Additive Manufacturing of S45C/H13 Dissimilar Metals: Si Heon Lee, Ha Jin Choi, Min Woo Yeon, Hyun Na Kim, Sae Hun Jeong, Chul Kyu Jin, Do Young Kim; J. Korean Soc. Precis. Eng. 2026;43(3):231-236.
Published online March 1, 2026; DOI: https://doi.org/10.7736/JKSPE.025.00027

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This study examines the porosity behavior during the directed energy deposition (DED) of dissimilar metals S45C and H13. We analyzed the effects of deposition parameters, including laser power, feed rate, and powder characteristics, on pore formation, taking into account the unique properties of these metals. Our findings indicate that laser power is the primary factor influencing porosity. At a low power of 200 W, insufficient energy input, along with differences in thermal conductivity and chemical composition between S45C and H13, led to incomplete melting and lack-of-fusion, resulting in high porosity. As the laser power increased to 400-600 W, the melt pool stabilized, enhancing interfacial bonding and significantly reducing porosity. However, at an excessive power of 800 W, rapid melting and solidification of the powder caused gas entrapment and pore formation, which increased porosity, particularly due to the differing thermal conductivities of S45C and H13. Therefore, our results suggest that maintaining an adequate laser power of 400-600 W is essential for achieving a stable melt pool and minimizing porosity in the DED process for dissimilar S45C and H13 metals.

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Effect of Flash-light Sintering Voltage on the Microstructure and Chemical Properties of Lithium Lanthanum Titanate Thin Films Prepared by Electrostatic Spray Deposition: Sun Min Kim, In Suk Song, Hyo Jun Ahn, Min Ji Kim, Young-Beom Kim; J. Korean Soc. Precis. Eng. 2026;43(1):55-60.
Published online January 1, 2026; DOI: https://doi.org/10.7736/JKSPE.025.056

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All-solid-state batteries (ASSBs) utilizing non-flammable inorganic electrolytes are gaining significant attention due to safety concerns associated with conventional lithium-ion batteries. Among various oxide electrolytes, lithium lanthanum titanate (LLTO) demonstrates high ionic conductivity at room temperature but is prone to lithium loss at elevated sintering temperatures. In this study, we employed electrostatic spray deposition (ESD) at 250℃, followed by flash light sintering within milliseconds using a xenon lamp. This approach enabled the production of dense and highly crystalline LLTO thin films with minimal lithium evaporation. Scanning electron microscopy (SEM) analysis confirmed reduced porosity at 650V, while X-ray photoelectron spectroscopy (XPS) revealed stable lithium content. Additionally, X-ray diffraction (XRD) indicated the formation of a cubic perovskite structure that is beneficial for ionic transport. This rapid and scalable process shows promise for producing high-quality LLTO electrolytes, thereby enhancing the safety and performance of next-generation ASSBs.

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A Review on Performance Improvement of Solid Oxide Cells via Atomic Layer Deposition: Min Seong Gwon, Kyoungjae Ju, Jihwan An; J. Korean Soc. Precis. Eng. 2025;42(12):987-995.
Published online December 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.00017

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Atomic Layer Deposition (ALD) has emerged as a promising technique for fabricating thin films that enhance the performance of solid oxide fuel cells and solid oxide electrolysis cells. ALD allows for precise control over film thickness and composition at the atomic level, resulting in uniform and dense thin films. These characteristics enable the deposition of thin, homogeneous layers of various materials onto the porous electrode surfaces of solid oxide cells, thereby increasing electrochemical activity and reducing activation losses. Additionally, thin-film electrolytes produced through ALD can achieve high ionic conductivity and low ohmic losses, facilitating a reduction in the operating temperature of solid oxide cells. This review summarizes recent research trends in applying ALD technology to the fuel electrode, air electrode, and electrolyte of solid oxide cells and discusses design strategies aimed at improving efficiency and long-term stability.

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Suppression of Interfacial Side Reactions and Performance Enhancement of NCA Cathodes via LNO Deposition Using Particle ALD: Min-ji Kim, In-suk Song, Hyo-jun Ahn, Sun-min Kim, Young-Beom Kim; J. Korean Soc. Precis. Eng. 2025;42(10):851-859.
Published online October 1, 2025; DOI: https://doi.org/10.7736/JKSPE.025.025

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Improving the interfacial stability between cathode active material (CAM) and solid electrolyte (SE) is essential for enhancing the performance and durability of all-solid-state batteries (ASSBs). One promising method to achieve this is through surface coating with a chemically stable ion conductor, which helps suppress interfacial side reactions and improve long-term cycling stability. In this study, we deposited a uniform LiNbO3 (LNO) protective layer on NCA using particle atomic layer deposition (Particle ALD). This technique utilizes a self-limiting growth mechanism to ensure precise thickness control. We characterized the structural and chemical properties of the coated CAM with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), confirming the successful formation of a uniform LNO layer. Electrochemical evaluations revealed that LNO@NCA exhibited significantly improved capacity retention, maintaining 68.1% after 50 cycles at a 1C rate, compared to just 56.5% for the uncoated sample. This enhancement is attributed to the LNO layer's effectiveness in mitigating electrochemical side reactions. These findings demonstrate that Particle ALD-derived LNO coatings are an effective strategy for stabilizing CAM|SE interfaces and extending the cycle life of high-energy ASSBs.

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Additional Ionomer-coated Layer for Self-humidifying Polymer Electrolyte Membrane Fuel Cells: Gyutae Park, Dongjin Kim, Junseo Youn, Junghyun Park, Hyoun-Myoung Oh, Taehyun Park; J. Korean Soc. Precis. Eng. 2023;40(12):997-1001.
Published online December 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.097

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In this study, we aim to develop a self-humidifying polymer electrolyte membrane fuel cell (PEMFC) by depositing platinum (Pt) on a membrane using sputtering. After we coated it with a Nafion^® ionomer solution. This is considered a solution that can prevent membrane degradation in low humidity conditions. By introducing this self-humidifying concept, we can expect improved performance compared to conventional PEMFCs. By managing the water content of Nafion^®, we aim to improve both the stability and performance of the PEMFCs. This research contributes to the development of more efficient and reliable PEMFC systems, showing promise for advances in this field.

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Laser-induced Deposition Method for Mask-less Copper Patterning on the Glass Substrate: Yonghoon Lee, Hwanggyu Lee, Dong Min Kim, Taewook Kim, Jisoo Kim; J. Korean Soc. Precis. Eng. 2023;40(12):965-973.
Published online December 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.084

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This study investigated the Laser-Induced Plasma Backward Deposition (LIPBD) process for transparent glass-copper composite film production. LIPBD was compared with Laser-Induced Backward Transfer (LIBT). Controlling laser parameters and the z-axis position of Depth of focus (DOF) resulted in various post-deposition outcomes. The optimal deposition depth was 10 μm to 90 μm, ensuring good glass-copper adhesion. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) mapping confirmed copper and copper oxide (CuO) particles. X-ray diffraction confirmed Cu and CuO peaks. The adhesive test showed a strong binding between glass and deposition, but the parts of the cracks caused by heat accumulation were delaminated during the test. LIPBD offers controlled deposition potential for glass-copper composites. Optimizing laser parameters leads to high-quality films. This study provides valuable insights into nanotechnology and the semiconductor industry, with potential applications across diverse fields.

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A Study on the Development of Adaptive 5-axis Path Generation CAM S/W for High Speed Metal 3D Printer: Sung Gun Lee, Hyun Chul Kim; J. Korean Soc. Precis. Eng. 2023;40(5):367-372.
Published online May 1, 2023; DOI: https://doi.org/10.7736/JKSPE.023.029

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This research developed a CAM S/W, which generates an adaptive 5-axis tool path, to optimize the quality of Direct Energy Deposition (DED) 3D printing. After reconstructing part shapes and generating printing paths in each shape, the path simulation including automatic collision detection was implemented. Productivity and printing quality were improved through equipment improvement and process optimization. In addition, high-quality parts with desirable physical and mechanical properties were produced by generating an adaptive 5-axis path specialized in the printing process that reflects various physical phenomena and monitoring results. Finally, the performance of CAM S/W was verified through the production of prototypes for industrial components.

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Effect on Bacterial Culture on Ceramic Surfaces Deposited Using a Laser: Sangwoo Yoon, Joohan Kim; J. Korean Soc. Precis. Eng. 2023;40(4):269-274.
Published online April 1, 2023; DOI: https://doi.org/10.7736/JKSPE.022.137

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The hydrophilicity of the cell culture substrate was controlled by depositing it on the alumina surface through the laser-induced backward transfer (LIBT) method. Alumina particles were sized using laser energy density and deposited on the soda lime glass surface. The particle size and hydrophilicity of the alumina deposition surface were evaluated by measuring the surface roughness, contact angle, and light diffusivity. As the particle size increased, the effect of alumina became stronger, and the deposited surface had relatively higher roughness, stronger hydrophilicity, and higher light diffusivity. The stronger the alumina effect, the lower the growth of Staphylococcus aureus on the deposited surface. In this study, it was confirmed that selective bacterial growth and culture could be controlled by adjusting the strength of the alumina coating using the LIBT process.

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Resistant Characteristics of AAO-Based Thin Film Solid Oxide Fuel Cells Using Ni-GDC Anode by GLAD Method: Jaewon Yoo, Myung Seok Lee, Yang Jae Kim, Suk Won Cha; J. Korean Soc. Precis. Eng. 2023;40(4):335-340.
Published online April 1, 2023; DOI: https://doi.org/10.7736/JKSPE.022.135

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In this study, we fabricated thin film solid oxide fuel cells on nanoporous anodic aluminum oxide (AAO) substrate for low-temperature operation using the all-through sputtering method. To deposit up to a three-micrometer thick anode with both porosity and electrical conductivity, we used the glancing angle deposition and co-sputtering methods. For the anode materials, we used nickel gadolinium-doped-ceria (Ni-GDC) mixed ionic and electronic conductor (MIEC), which improved hydrogen oxidation reaction reactivity at the anode side. TF-SOFCs were successfully operated at 500℃, and 223.6 mW/cm² was their highest measured maximum power density. We conducted structural and electrochemical analyses to figure out cells’ unique resistant characteristics; ohmic resistance through the anode thin film and polarization resistance of reaction area near the narrowed anode pores. We found how the anode thin film thickness affects the current collecting performance and the anode reactivity, and their effects were qualitatively and quantitatively compared.

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Cathodic Functional Layer via Sputtering and Atomic Layer Deposition for Thin-Film Solid Oxide Fuel Cells: Jaeyoon Lee, Sanghyeok Lee, Hyeontaek Kim, Yongchan Park, Geunjin Lee, Changheon Lee, Sunggyu Choi, Soonwook Hong; J. Korean Soc. Precis. Eng. 2022;39(2):97-102.
Published online February 1, 2022; DOI: https://doi.org/10.7736/JKSPE.021.123

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In this study, Yttria-stabilized zirconia (YSZ) functional layers were applied with different thin-film fabrication process such as sputtering and atomic layer deposition (ALD) to enhance oxygen reduction reaction (ORR) for solid oxide fuel cells. We confirmed that the YSZ functional layer deposited with sputtering showed relatively low grain boundary density, while the YSZ functional layer deposited with the ALD technique clearly indicated high grain boundary density through scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results. The YSZ functional layer coated with the ALD technique revealed that more ORR kinetics can occur using high grain boundary density than the functional layer deposited with sputtering. The peak power density of the SOFC deposited with ALD YSZ indicates 2-folds enhancement than the pristine SOFC.

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Flexible Post-Process Machining of the Directed Energy Deposition (DED) Printed Part through the On-Machine Measurement: Hoon-Hee Lee, Min-Suk Park, Dong-Mok Lee, Seung-Han Yang; J. Korean Soc. Precis. Eng. 2020;37(12):881-888.
Published online December 1, 2020; DOI: https://doi.org/10.7736/JKSPE.020.068

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The directed energy deposition (DED) process has been used for enhancement of the mechanical property, repair, and part manufacturing. Post-process machining is required due to the low quality of the DED printed part. Even if the part is printed under similar conditions, dimensional variations occur frequently due to the accumulation of small printing errors. Due to tool overfeeding and the occurrence of the non-cutting area due to this variation, the quality of the finished part is not guaranteed. Therefore, the post-process machining should be carried out considering the actual printed part shape. Herein, the flexible post-process machining is proposed by utilizing the shape information through the on-machine measurement (OMM) of DED printed parts. The process margin for machining the design shape is calculated through the OMM of the geometric dimension of the printed part. Feedrate (Override) and machining path of each printing parts are flexibly determined depending on the process margin. This technique is applied to the pocket shape part printed with STS 316L material, and the rough and finish machining conditions are established. Rough machining time was reduced by adjusting the feedrate flexibly. The final form of accuracy and surface roughness were achieved under 30 and 0.25 μm, respectively.

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Preparation of SrCo_0.8Nb_0.1Ta_0.1O_3-δ as a Cathode for Solid Oxide Fuel Cells by Pulsed Laser Deposition: Sangbong Ryu, Wonjong Yu, Arunkumar Pandiyan, Sanghoon Lee, Wonyeop Jeong, In won Choi, Myung Seok Lee, Suk Won Cha; J. Korean Soc. Precis. Eng. 2020;37(1):83-87.
Published online January 1, 2020; DOI: https://doi.org/10.7736/JKSPE.019.051

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Recently, new perovskite cathode material, SrCo_0.8Nb_0.1Ta0.1O_3-δ (SCNT) was reported, showing high oxygen reduction reaction (ORR) activity. This study demonstrates thin film deposition of SCNT by pulsed laser deposition technique applied to anodic aluminum oxide (AAO) based thin-film solid oxide fuel cells (TF-SOFCs) to assess the possibility of SCNT application to TF-SOFCs. The SCNT powder and the target were prepared by the solid state reactive sintering method (SSRS). This target was then mounted to the pulsed laser depositing machine and deposited on the Si wafer, and the nano-porous substrate, AAO. The physical structure and the chemical phase were investigated by the field emission scanning electron microscope, focused ion beam scanning electron microscope, and X-ray diffraction. On the top of the AAO, thin Pt film and yttria stabilized zirconia (YSZ) were first deposited by sputtering and the SCNT was deposited on the top of it afterward. The open circuit voltage of AAO cell was tested at 500°C, and successful polarization activity of SCNT was observed.

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Fabrication of Micro Pattern Through Analysis of Contact Area of the Jet-Circulating Electrodeposition: Haan Kim, Chong Nam Chu; J. Korean Soc. Precis. Eng. 2019;36(6):523-529.
Published online June 1, 2019; DOI: https://doi.org/10.7736/KSPE.2019.36.6.523

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In the Jet-Circulating electrodeposition, selective electrodeposition is done using the local circulation of the electrolyte. The Scale of fabricated patterns using the Jet-Circulating electrodeposition is dependent on the contact area between the nozzle and the workpiece surface through the electrolyte circulation. The shape of the electrolyte meniscus determines the contact area. The factors that influence the shape of the meniscus include the electrolyte jetting parameter and the characteristics of the workpiece surface. The jet distances are analyzed based on the shape of the electrolyte meniscus and contact area which is dependent on the jetting pressure and the suction pressure. In order to investigate the effect of contact area on the workpiece surface, the surface is treated using Hexamethyldisilazane spin coating, self-assembled monolayer formation, and Neverwet ® spray coating. The contact angle and the contact area based on the surface treatment methods are analyzed. The width of the copper patterns fabricated through Jet-Circulating electrodeposition are compared. The copper pattern width of the self-assembled monolayer formation surface had reduction of 30% in comparison to the untreated surface.