Mg–Bi–Al–Mn 초고속 마그네슘 압출재의 미세조직 및 기계적 특성

차재원,진상철,박성혁 한국소성∙가공학회 2022 소성가공 : 한국소성가공학회지 Vol.31 No.2

In this study, a developed Mg–5Bi–2Al–0.4Mn (BAM520, wt%) alloy was successfully extruded at an extremely high speed of 70 m/min. Microstructural evolution during extrusion and the microstructural characteristics and tensile properties of the very-high-speed extruded BAM520 alloy were then investigated. The homogenized BAM520 billet contained only thermally stable Mg3Bi2 phase particles without any Mg17Al12 phase with a low melting temperature. Therefore, the BAM520 alloy exhibited excellent extrudability. The very-high-speed extruded BAM520 alloy had a completely recrystallized grain structure and a typical basal fiber texture. Despite the extremely high extrusion speed of 70 m/min, the extruded BAM520 alloy had a high ultimate tensile strength of 280 MPa due to combined strengthening effects of a small grain size, numerous fine Mg3Bi2 particles, and strong basal texture.

Mg–5Bi–3Al 마그네슘 고속 압출재의 미세조직과 고주기피로 특성

차재원,진상철,박성혁 한국소성∙가공학회 2022 소성가공 : 한국소성가공학회지 Vol.31 No.5

In this study, the microstructural characteristics of a high-speed-extruded Mg–5Bi–3Al (BA53) alloy and its tensile, compressive, and high-cycle fatigue properties are investigated. The BA53 alloy is successfully extruded at a die-exit speed of 16.6 m/min without any hot cracking using a large-scale extruder for mass production. The homogenized BA53 billet has a large grain size of ~900 μm and it contains fine and coarse Mg3Bi2 particles. The extruded BA53 alloy has a fully recrystallized microstructure with an average grain size of 33.8 μm owing to the occurrence of complete dynamic recrystallization during high-speed extrusion. In addition, the extruded BA53 alloy contains numerous fine lath-type Mg3Bi2 particles, which are formed through static precipitation during air cooling after exiting the extrusion die. The extruded BA53 alloy has a high tensile yield strength of 175.1 MPa and ultimate tensile strength of 244.4 MPa, which are mainly attributed to the relative fine grain size and numerous fine particles. The compressive yield strength (93.4 MPa) of the extruded BA53 alloy is lower than its tensile yield strength, resulting in a tension-compression yield asymmetry of 0.53. High-cycle fatigue test results reveal that the extruded BA53 alloy has a fatigue strength of 110 MPa and fatigue cracks initiate at the surface of fatigue test specimens, indicating that the Mg3Bi2 particles do not act as fatigue crack initiation sites. Furthermore, the extruded BA53 alloy exhibits a higher fatigue ratio of 0.45 than other commercial extruded Mg–Al–Zn-based alloys.

진정성 리더십이 종업원의 조직열의, 직무만족, 창의성, 그리고 직무성과에 미치는 영향: 프랜차이즈 호텔을 중심으로

차재원,김은정,정규엽 한국프랜차이즈경영학회 2017 프랜차이즈경영연구 Vol.8 No.4

Purpose - In hotel business, how to build the relationship between leader and employees is very important, because it affects on the customer satisfaction. Thus, this research examines the effect of authentic leadership on job performance in the context of hotel industry and identifies mediating roles of organizational engagement, job satisfaction, and creativity in the relationship between authentic leadership and job performance. This study suggests the guidelines for how hotel companies should improve employee productivity and build a desirable organizational culture by presenting employee attitudes and behavioral models that explain the relationship between leaders and employees. Research design, data, and methodology - This study examines the structural relationship between authentic leadership, organizational engagement, job satisfaction, creativity, and job performance from the employee’s perspective. Authentic leadership divide into four sub-dimensions such as self-awareness, balanced process of informations, internalized moral perspective, and relational transparency. In order to test the purposes of this study, research model and hypotheses were developed. All constructs were measured with multiple items developed and tested in the previous studies. The data were collected from 114 franchise hotel employees and were analyzed using SPSS 21.0 and Smart PLS 3.0. program. Result - The results of this study are as follows. First, authentic leadership have significant impacts on organizational engagement and creativity, but does not have impact on job satisfaction directly. Second, organizational engagement have significant impacts on job satisfaction and job performance, but does not have impact on creativity directly. Third, job satisfaction has significant impact on creativity, but does not have impact on job performance. Fourth, creativity has significant impact on job performance. Conclusions - The findings of this study indicate that hotel leaders should properly implement the authentic leadership and consider how to build a corporate culture to improve an organizational and employee productivity through authentic leadership. Due to the nature of the hotel industry, which relies heavily on human resources, hotel companies must manage their employees with authenticity in order to increase organizational engagement, job satisfaction, and creativity that affect hotel and employee productivity. If hotel employees perceive their leader's authentic leadership, they show more organizational engagement that increases creativity and leads to job performance. Finally, hotel employees can propose creative ideas only if they will be satisfied with their jobs. Therefore, the leader should develop non-monetary or monetary reward system for the employees and, make an efforts to foster creativity of the employees.

반도체 플립칩 몰드 설계를 위한 가압식 Underfilling 수치해석에 관한 연구

차재원,김광선,서화일 호서대학교 반도체제조장비국산화연구센터 2003 학술대회 자료집 Vol.2003 No.1

IC 패키지 기술중 Underfilling 은 칩과 기판 사이에 Encapsulant의 표면장력을 이용하여 주입하고 경화시킴으로써 전기적 기계적 보강력을 제공하는 기술로서 시스템 침의 발전과 함께 차세대 패키징 기술중의 하나이다. 본 연구에서는 기존의 Underfilling 공정을 개선하여 충전시간을 획기적으로 줄일 수 있는 가압식 Underfilling 공정을 이용하여 차세대 반도체 패키징에 적용할 수 있는 가능성을 파악하였다. 이를 위하여 칩과 기판사이에 주입되고 경화되는 Encapsulant의 유동 특성을 파악하였다. 가압식 Underfilling 기술은 아직까지 상용화되지 않은 미래기술로써 효율적인 몰드 설계를 위하여 Encapsulant 종류에 따라 Gate 위치, Bump pattern 및 개수, 칩과 기판 사이의 거리, Side region에 따른 유동특성 파악이 중요하다. 본 연구에서는 DEXTER^TM(US)의 Encapsulant FP4511을 사용하여 Cavity 내에 Void를 없앨 수 있는 주입조건을 찾아내고 Underfilling 시간을 감소시킬 수 있는 모사를 진행하였다.

[정치풍향] 김기현 대표 체제로 재편된 국민의힘의 행로_국민의힘에서 ‘尹의힘’ 됐다

차재원 중앙일보에스 2023 中央(月刊) Vol.2023 No.4

Low Cost Endurance Test-pattern Generation for Multi-level Cell Flash Memory

차재원,조기원,유승건,강성호 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.1

A new endurance test-pattern generation on NAND-flash memory is proposed to improve test cost. We mainly focus on the correlation between the data-pattern and the device error-rate during endurance testing. The novelty is the development of testing method using quasi-random pattern based on device architectures in order to increase the test efficiency during time-consuming endurance testing. It has been proven by the experiments using the commercial 32 nm NAND flash-memory. Using the proposed method, the error-rate increases up to 18.6% compared to that of the conventional method which uses pseudo-random pattern. Endurance testing time using the proposed quasi-random pattern is faster than that of using the conventional pseudo-random pattern since it is possible to reach the target error rate quickly using the proposed one. Accordingly, the proposed method provides more low-cost testing solutions compared to the previous pseudo-random testing patterns.

호텔 레스토랑에서 임파워먼트와 고객지향성이 지배인의 직무태도와 협력행동에 미치는 영향

정규엽,차재원,한상호,이두진,이용기 한국호텔관광학회 2013 호텔관광연구 Vol.15 No.3

The purpose of this study is to investigate how empowerment influences customer orientation, and in turn, how customer orientation influences job satisfaction, organizational commitment, and helping behavior in hotel foodservice industry. In addition, this research examines the mediating roles of job satisfaction and organizational commitment in the relationship between customer orientation and helping behavior. For these purposes, the data were collected from 200 hotel employees and analyzed using SPSS 18.0 and AMOS 18.0. The results are as follows: First, empowerment influences customer orientation. Second, customer orientation influences both job satisfaction and organizational commitment. Third, job satisfaction influences organizational commitment, but has no effect on helping behavior. Finally, organizational commitment influences helping behavior. At the end of this paper, limitations and further research directions are suggested.

빌렛 형상 제어를 통한 Mg–5Bi 합금 압출재의 조직 균일도 및 기계적 물성 변화

진상철,차재원,박성혁 한국소성∙가공학회 2022 소성가공 : 한국소성가공학회지 Vol.31 No.6

Extruded Mg–Bi binary alloys are known to have an undesirable bimodal grain structure containing a large amount of coarse unrecrystallized grains. Accordingly, to improve the microstructural homogeneity of extruded Mg–Bi alloys, it is necessary to promote the dynamic recrystallization (DRX) behavior during hot extrusion. An effective way to promote DRX is an increase in nucleation sites for DRX through a pre-deformation process before extrusion, such as cold pre-forging and hot pre-compression. However, the application of these pre-deformation processes increases the cost of final extruded Mg products because of an increase in energy consumption and decrease in productivity. Therefore, a low-cost new continuous process with high productivity is required to improve the microstructural homogeneity and mechanical properties of extruded Mg alloys without a drastic increase in the entire process cost. This study proposes a new extrusion method using an extrusion billet with a truncated cone shape (i.e., tapered billet) instead of a conventional extrusion billet with a cylindrical shape. When the hot extrusion of a Mg–5Bi alloy is conducted using the tapered billet, the DRX behavior during extrusion is considerably promoted. The DRX fraction and average grain size of the extruded alloy significantly increase and decrease from 65% to 91% and from 225 μm to 49 μm, respectively. Consequently, the extruded Mg–5Bi alloy fabricated using the tapered billet has a finer homogeneous grain structure and higher tensile elongation than the extruded counterpart fabricated using the cylindrical billet.

프랜차이즈 호텔의 LMX가 종업원의 직무스트레스, 직무역할성과, 그리고 충성도에 미치는 영향

김은정,차재원,강태원 한국프랜차이즈경영학회 2018 프랜차이즈경영연구 Vol.9 No.4

Purpose – In hotel industry, quality of leader-member exchange(LMX) relationship is very critical, because it impacts on the employee’s work attitude and behaviors. Thus, this research examines the effect of LMX on employee loyalty in the context of hotel business and identifies mediating roles of work stressors, work role performance in the relationship between LMX and employee loyalty. This research suggests the guidelines for how hotel leaders should manage their employees and build employee loyalty that improve management and business performance. Research design, data, and methodology - This study tests the structural relationship between LMX, work stressors, work role performance, and employee loyalty. Work role performance divide into three sub-dimensions such as individual task proficiency, individual task adaptivity, and individual task proactivity. In order to examine the purposes of this research, research model and hypotheses were developed. All constructs were measured with multiple items developed and tested in the previous studies. The data were collected from 113 franchise hotel employees and were analyzed using SPSS 22.0 and SmartPLS 3 program. Result – The findings of this research are as follows. First, leader-member exchange(LMX) have significant positive impacts on work stressors, work role performance, and employee loyalty. Second, work stressors have significant negative impacts on work role performance and employee loyalty. Third, work role performance has significant positive impact on employee loyalty. Conclusions – The outcomes of this research indicate that hotel leaders should focus on the dyadic relationship with their employees how to improve employee productivity through LMX relationship. In turn, the quality of this relationship influences employees’s work attitudes and behaviors. As a result of increasing job demands in hotel business which relies heavily on human resources, the hotel leader must find ways to prevent or reduce stressors and associated strains. If hotel employees perceive the high quality of LMX relationship, they improve their work role performance which influences loyalty. Therefore, the hotel leaders should develop monetary or non-monetary reward system for the employees and, make an efforts to have unique social exchange relationships with employees.

단일치아 임플란트의 성공률에 관한 임상적 연구

민승기,차재원,오승환 대한악안면성형재건외과학회 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.6