소결 기어용 표면치밀화 기술 개발

김기정(Kijung Kim),김기범(Kibum Kim),김성진(Seong Jin Kim),박현달(Hyundal Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

The novel PM (powder metallurgy) steel for automotive power-train gear components were developed to reduce manufacturing cost, while meeting the requirements. The high-density PM steel was manufactured by mixing using special Cr-Mo atomized iron powders, high-pressure compaction, and sintering. Tensile strength, charpy impact, bending fatigue, and contact fatigue tests for the PM steel were carried out comparing to the conventional forged steel. The pinion gears for 6-speed auto-transmission were also manufactured by helical pressing, sintering, and external rolling process (selective surface densification). In order to evaluate the durability of the PM parts, the auto-transmission durability tests were performed using dynamometer tests. Results showed that the PM steel fulfilled the requirements for pinion gears indicating suitable bending and contact fatigue strengths. The PM gears also showed improved gear tooth profile and better performance during the transmission durability tests. In particular, the PM gears manufactured by helical pressing and selective surface densification showed a significant advantage in reducing the manufacturing cost of about 30% as compared to the conventional forged steel gear manufactured by tooth machining (hobbing, shaving, and grinding) process.

Investigations on association schemes with elementary abelian thin residue

Kim, Kijung,Song, Sung-Yell,Xu, Bangteng North-Holland Pub. Co 2017 Discrete mathematics Vol.340 No.12

<P><B>Abstract</B></P> <P>In this paper, we give a new class of association schemes whose thin residues are isomorphic to an elementary abelian p -group of order <SUP> p 2 </SUP> . We then study the automorphism groups of these schemes and determine whether these schemes are schurian.</P>

An autodriven, solar fuel collection for a highly compact, biomimetic-modified artificial leaf without membrane

Kim, Sangkuk,Han, Kiduk,Kim, Wuseok,Jeon, Sangmin,Yong, Kijung Elsevier 2019 Nano energy Vol.58 No.-

<P><B>Abstract</B></P> <P>Hydrogen fuel generation from water splitting has recently attracted much attention due to its high potential as a clean, renewable energy source. To obtain pure H<SUB>2</SUB> fuel, it is inevitably required to separate the H<SUB>2</SUB>/O<SUB>2</SUB> product gas mixture, mainly relying on a membrane system at the current stage. However, this process has inherent durability and cost issues due to contamination, corrosion and its complex configuration. In our current work, we invented a highly compact gas separation and collection method in a water electrolysis system, which is set onto a biomimetically modified electrode without the use of a membrane or external convective flow. A key idea of this smart, compact and self-driven system is gas bubble manipulation by buoyant force and a slippery liquid infused porous surface (SLIPS). With the critical help of the biomimetic SLIPS wall by blocking bubble leakage, H<SUB>2</SUB> and O<SUB>2</SUB> product gases can be separately collected at the corresponding collection port. As a result, we achieved a remarkably improved H<SUB>2</SUB> collection value of over 90% with high purity using this membrane-free electrolysis system in which the product gases are separated only by their intrinsic buoyancy. This simple but effective gas separation/collection system is also applied to a highly compact, monolithic artificial leaf, in which the solar water splitting is practicably and conveniently conducted in a compact, floatable design.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A membrane-free gas separation method is invented for monolithic artificial leaf. </LI> <LI> Buoyance force and biomimetic surface design is combined for gas bubble manipulation. </LI> <LI> The collection efficiency of H<SUB>2</SUB> gas records over 90% with its high purity. </LI> <LI> O<SUB>2</SUB> gas, counter product of water electrolysis shows very low cross-over with high purity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A membrane-free, compact solar fuel collection system employing the biomimetic SLIPS of the pitcher plant with water splitting electrodes, showing its mechanism and performance in its gas separation/collection.</P> <P>[DISPLAY OMISSION]</P>

Communication—Selective Adsorption of PEG on SiO₂ for High Removal Selectivity in Tungsten CMP

Kim, Kijung,Lee, Kangchun,So, Sounghyun,Cho, Sungwook,Lee, Myeongjae,You, Keungtae,Moon, Jinok,Song, Taeseup The Electrochemical Society 2018 ECS journal of solid state science and technology Vol.7 No.3

<P>We studied the effect of selective adsorption of polyethylene glycol (PEG) on SiO2 for high removal selectivity of tungsten to SiO2 in tungsten CMP. The hydrogen bonding between PEG and SiO2 increased as the solution pH decreased. At pH 3, the maximum adsorption of PEG on SiO2 occurred due to the low surface charge of SiO2 (near its isoelectric point). The selective adsorption led to the selective reduction of removal rate of SiO2 during CMP process. As a result, the removal selectivity increased from 4.5 to 85.5 as the PEG concentration increased from 0 to 9 wt% at pH 3. (C) 2018 The Electrochemical Society.</P>

A Study on the Performance Analysis of MILITARY Culture Innovation

Kijung Kim,Wonseok Kang J-INSTITUTE 2021 International Journal of Military Affairs Vol.6 No.1

Purpose: This study was conducted to evaluate and analyze whether the military culture innovation, which has been being promoted since 2014, is doing well through a survey of Army soldiers on "A Survey on the Feelings of Military Culture Innovation." In particular, a qualitative performance analysis of military culture innovation was conducted through a survey on the awareness and satisfaction of soldiers who are experiencing military culture innovation in personally. Method: In this work, we selected suitable questions for the study through factor analysis of the SPSS program and conducted the study in two main ways on selected questions. The first is to conduct an analysis of the performance of military culture innovation through the average of the selected detailed questions for each part on the five implementations of military culture innovation. Second, we divided the officers and soldiers among the survey respondents to see if the results of their survey on the level of military culture innovation showed a difference, and analyzed whether the difference was significant through the SPSS program's independent sample T test. Results: The results of the analysis conducted using selected questions through factor analysis are as follows: First, as a result of the analysis of the feeling of military culture innovation, we produced positive results that we are "somewhat satisfied" with all five implementations. Second, there was a significant difference between the officer group and the soldier group in terms of the sense of military culture innovation. Conclusion: This study was conducted using the most survey results among the performance analysis of mili-tary culture innovation that has ever been done, so the reliability is very high. In addition, it is of great value in that it analyzed quality performance based on the feelings and thoughts of soldiers who are experiencing military culture innovation directly, not performance analysis relying on quantitative results. Through this, we hope that it will help to accurately diagnose the current military culture innovation and find constructive improvements in the future.

Fenton-Like Reaction between Copper Ions and Hydrogen Peroxide for High Removal Rate of Tungsten in Chemical Mechanical Planarization

Kim, Kijung,Lee, Kangchun,So, Sounghyun,Cho, Sungwook,Lee, Myeongjae,You, Keungtae,Moon, Jinok,Song, Taeseup The Electrochemical Society 2018 ECS journal of solid state science and technology Vol.7 No.3

<P>The Fenton reaction has been used for the tungsten oxidation under acidic conditions in tungsten chemical mechanical planarization (CMP). However, the narrow working pH window required for ideal reaction limits its application. Herein, we report a simple Fenton-like system via the reaction between copper ion and hydrogen peroxide (H2O2) for the tungsten oxidation over a broad pH range. Copper ion was employed as a reactant with H2O2 for the Fenton-like reaction, resulting in high production rates of hydroxyl radicals in the range of acidic to neutral pH, which leads to a high rate of tungsten oxidation. As a result, the Fenton-like reaction between copper ions and H2O2 enables the high removal rates of tungsten films during CMP process in acidic to neutral pH ranges. (C) 2018 The Electrochemical Society.</P>

Increase in Ce³⁺ Concentration of Ceria Nanoparticles for High Removal Rate of SiO₂ in Chemical Mechanical Planarization

Kim, Kijung,Yi, Dong Kee,Paik, Ungyu The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.9

<P>Ceria nanoparticles (NPs) are used as abrasives for silicon dioxide (SiO<SUB>2</SUB>) chemical mechanical planarization (CMP) due to the strong chemical bonds between the Ce<SUP>3+</SUP> ions of ceria NPs and the hydrated silicate species on the surface of SiO<SUB>2</SUB> films. However, the limited concentration of Ce<SUP>3+</SUP> ions in ceria NPs remains a major challenge for this application. Herein, we report a simple strategy to synthesize ceria NPs with high concentrations of Ce<SUP>3+</SUP> ions for enhanced adsorption reactions with silicate anions. Three types of ceria NPs approximately 70 nm in size were synthesized via the aggregation of different sized primary NPs. As the particle size of the primary NPs decreased from 70 nm to 5 nm, the Ce<SUP>3+</SUP> concentration of the ceria NPs increased from 15.6 to 24.0%. The adsorption isotherm fits the Freundlich model and the constants of adsorption capacity (K<SUB>F</SUB>) and adsorption intensity (1/n) indicate that the adsorption affinity for silicate anions increased with increasing Ce<SUP>3+</SUP> concentration. The increase in Ce<SUP>3+</SUP> concentration led to an increase in the chemical adsorption between ceria NPs and silicate anions, resulting in a high removal rate of SiO<SUB>2</SUB> during CMP.</P>

Effective soil population control of root-knot nematode using Beauveria bassiana JEF-503 with environmental safety

Kijung Kim,Yearam Im,Hanna Yang,Jae Su Kim 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.10

Root-knot nematode (RKN), Meloidogyne incognita, inflicts significant greenhouse crop damage, causing over 40% economic losses. While chemical agents effectively control RKN, they leave harmful residue in soil and crops. To address this issue, we investigated soil-derived entomopathogenic fungi (EPF) in this study. We assessed the nematicidal impact of ten EPF species through in vivo and in vitro tests. Beauveria bassiana JEF-503 exhibited nematicidal effectiveness exceeding 65% in both experimental settings. In a semi-field test using greenhouse pots, we experimented with the application of B. bassiana JEF-503 suspension during tomato growth, which is an uncommon practice in comparison to chemical treatments due to residue concerns. B. bassiana JEF-503 was applied during transplantation, and the same application was repeated four weeks later. JEF-503 One-time and abamectin treatments were used as control groups. The JEF-503 two-time application notably reduced root damage compared to single JEF-503 or abamectin treatment. In conclusion, JEF-503 offers a promising, residue-free, and environmentally friendly alternative to chemical agents for RKN management.

Communication—Reduction of Friction Force between Ceria and SiO₂ for Low Dishing in STI CMP

Kim, Kijung,Lee, Kangchun,Seo, Jihoon,Song, Taeseup The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.10

<P>We investigated the effect of friction force between ceria abrasive and SiO<SUB>2</SUB> film on dishing in STI CMP. The control of adsorption amount of poly acrylic acid (PAA) on ceria surface led to the reduction of the friction force during CMP. The reduced friction force by a thick surface layer on ceria resulted in the decrease of the dishing in STI structure during over-polishing process. In the patterned wafer, the dishing decreased from 976 to 594 Å/min at 37.5% pattern density (Si<SUB>3</SUB>N<SUB>4</SUB>/SiO<SUB>2</SUB> = 30/50 μm) as a maximum adsorption amount increased from 0.49 to 0.64 mg/m<SUP>2</SUP>.</P>

Highly Dispersed Fe³⁺-Substituted Colloidal Silica Nanoparticles for Defect-Free Tungsten Chemical Mechanical Planarization

Kim, Kijung,Seo, Jihoon,Lee, Myeongjae,Moon, Jinok,Lee, Kangchun,Yi, Dong Kee,Paik, Ungyu The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.7

<P>Silica nanoparticles (NPs) are used as abrasives for tungsten chemical mechanical planarization (CMP) at acidic pH. However, the use of silica NPs at pH near their isoelectric point remains a problem because agglomeration due to low surface charge leads to defects on the tungsten surface during CMP. Herein, we report a simple strategy to increase the surface charge of silica NPs at acidic pH for defect-free tungsten CMP. The isomorphic substitution of Si4+ by Fe3+ ions on the surface of silica NPs by hydrothermal reaction led to a pH-independent permanent negative surface charge, which increased as the concentration of substituted Fe3+ ions increased. At acidic pH, the increased negative surface charge of Fe3+-substituted silica (Fe-silica) NPs resulted in a reduction in the number of agglomerated large particles relative to that of pure silica NPs. As a result, highly negatively-charged Fe-silica NPs showed high performance in the reduction of defect count on the tungsten surface after CMP. (C) 2017 The Electrochemical Society. All rights reserved.</P>