울릉도 토기 산지에 대한 지구화학적 연구

홍영국(Young Kook Hong),이승구(Sung Koo Lee) 한국암석학회 2009 한국암석학회 학술발표회 논문집 Vol.2009 No.5

이온교환법에 의한 치과용도재의 강도증진 효과에 관한 실험적 연구

이영국,이선형,양재호,Lee Young-Kook,Lee Sun-Hyung,Yang Jae-Ho 대한치과보철학회 1991 대한치과보철학회지 Vol.29 No.3

Ion exchange strengthening is a chemical process whereby large alkali ions(such as potassium) are substituted for smaller ions(sodium) within the surfaces of glasses and ceramics, thereby reducing the thermal expansion coefficient of this surface region, and creating beneficial state of compressive stress within the near surface region. The purpose of this study was to determine the effects of ion exchange and etching treatments on the strength of some dental porcelains. Two feldspathic dental porcelains(Vitadur-N, G-Cera) were used in this study. A commercial ion exchange paste and etching gel containing 8% hydrofluoric acid were used for surface conditioning. Transverse strength was measured using a universal testing machine and the technique of EPMA(electron probe micro analysis) was used to access the potassium contents. The results were as follows: 1. Improvement in strength was only obtained by treating the surface placed in tension. 2. No changes in the dimensions of the treated specimens were detected when samples were measured with a micrometer. 3. There was significant increase in transverse strength of G-Cera IV group treated with etching and ion exchange, compared with G-Cera II group only treated with ion exchange. 4. From the results of EPMA test, increase in potassium contents was observed on the surface treated with ion exchange paste.

3상 PWM Converter를 위한 정지 좌표계법 Analog 제어기 설계 및 시뮬레이션

이영국(Young-kook Lee),노철원(Chul-won Noh),최종률(Song-yul Choe) 전력전자학회 1997 전력전자학술대회 논문집 Vol.1997 No.-

Due to several advantages of pulse width Modulated(PWM) Converter, such as unity power factor with low-harmonics and energy regeneration, PWM convener has been widely used in industrial application<br/> In every application of energy conversion equipment, the design and Implementation must be carried out considering performance and cost High quality with low cost is me best choice for energy conversion equipment<br/> High dc link voltage can reduce Inverter and motor side losses and system dimension compare to low dc link voltage-Analog controller can make PWM converter cheaper without considerable degradation of the performance than digital Controller. This paper shows the simplified analog controller for 600V dc link voltage using stationary reference frame control and the simulation results

V-Nb Microalloyed 강의 오스테나이트역에서 복합 탄질화물의 재용해 및 석출 거동

이영국 ( Young Kook Lee ),정재길 ( Jae Gil Jung ),하양수 ( Yang Soo Ha ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.12

Dissolution and precipitation behaviors of complex carbonitrides in austenite of a V-Nb microalloyed steel were quantitatively examined through electrical resistivity measurement and transmission electron microscopy. The electrical resistivity increased with solution treatment temperature up to 1240℃ and then was saturated at 225 nΩm for a holding time of 10 min. The electrical resistivity method was also used to quantitatively measure the isothermal precipitation kinetics of the complex carbonitrides in austenite. Nbrich precipitates were observed in austenite at the early stages of precipitation, but Nb was replaced by V up to the equilibrium amount within the precipitates with further holding time. The time-temperatureprecipitation diagram showed a C-type curve; nose temperature and its incubation time were 900℃ and 100 s, respectively.

팔당댐 하류 한강유입 지류천에서의 에스트로겐 자류실태 조사

함영국(Young-Kook Ham),이민주(Min-Joo Yi),김현숙(Hyun-Suk Kim),기효석(Hyo-Suk Ki),이수원(Su-Won Lee),한선희(Sun-Hee Han) 한국환경독성학회 2010 한국독성학회 심포지움 및 학술발표회 Vol.2010 No.11

아날로그 히스테리시스 전류 제어기를 적용한 3상 PWM 컨버터 개발

이영국(Young-kook Lee),노철원(Chul-won Noh) 전력전자학회 2001 전력전자학술대회 논문집 Vol.2001 No.7

Due to several advantages of Pulse Width Modulation (PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system.<br/> In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments.<br/> So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.

글로벌경쟁력 제고에 혼신의 노력을

이영국(Young-Kook Lee) 한국자동차공학회 2007 오토저널 Vol.29 No.1

리뷰논문 : 방진합금

이영국,최종술 ( Young Kook Lee,Chong Sool Choi ) 대한금속재료학회 ( 구 대한금속학회 ) 1994 상변태 심포지엄 Vol.5 No.-

회의 중 정서노동의 원인과 결과 : 조절초점 전략에 따른 차별적 매개효과

문영국(Young-Kook Moon),이종현(Jong-Hyun Lee),신강현(Kang-Hyun Shin) 한국인사관리학회 2020 조직과 인사관리연구 Vol.44 No.4

본 연구는 기업에서 대부분의 종업원들이 일상 업무에서 경험하는 회의에 대한 연구이다. 회의 중 개 인의 조절초점 전략이 정서노동 전략을 통해 회의만족에 끼치는 효과를 검증하였으며, Higgins(1997)의 조절초점이론을 근거로 개인의 조절초점에 따라 회의상황에서 다른 정서를 경험하여 각각에 적합한 전략을 통해 서로 다른 회의만족 수준을 경험하는지 알아보았다. 직장인 253명을 대상으로 구조방정 식 모형을 사용하여 조절초점에서 각각의 회의정서노동전략으로 경로계수(예방초점-내면행동; 향상초 점-표면행동)를 추가한 경쟁모형 비교를 통해 연구모형이 타당함을 검증하였으며, 회의에서 개인의 조 절초점에 따라 차별적인 정서노동전략이 나타남을 확인하였다. 다음으로 Bootstrap 검증을 이용하여 연구모형에서 향상초점이 회의만족에 끼치는 정적 효과는 내면행동을 통해, 예방초점이 회의만족에 끼 치는 부적 효과는 표면행동을 통해 매개되는 간접효과가 유의미함을 확인하였다. 본 연구를 통해 개인 의 조절초점 전략이 회의정서노동의 선행변인으로 기능함을 알 수 있었고, 기존 회의표면행동과 지각 된 회의효과성 간 관계뿐만 아니라 회의내면행동의 효과와 회의만족 간 관련성을 추가로 확인해볼 수 있었다. 끝으로 본 연구의 시사점과 제한점, 후속연구의 방향성을 논의하였다. This study examined the mediation effect of emotion labor strategy to describe the relationships between regulatory focus strategies and meeting satisfaction. Based on Regulatory Focus Theory by Higgins(1997), this study expected that different personal motivation tendencies in meetings will experience different meeting satisfactions, because of using the distinct emotional labor strategies (prevention focus with surface acting, promotion focus with deep acting). To investigate the mediation effect, this study used structural equation modeling and 253 samples of the employees. Firstly, comparison with competitive model, the research model had more appropriate fit with sample, and also identified that employees with different regulatory focus choose specific emotional labor strategy in work meetings. Next, this study confirmed that the effect of promotion focus on meeting satisfaction was mediated by deep acting. On the contrary, the influence of prevention focus on meeting satisfaction was mediated by surface acting, and the significance of 2-indirect effects was supported by Bootstrap method. Lastly, implications, limitations and future research directions were discussed.

치과용도재에 의한 법랑질 마모에 관한 연구

이영국,이선형,양재호,정헌영,Lee, Young-Kook,Lee, Sun-Hyung,Yang, Jae-Ho,Chung, Hun-Young 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.1

Dental porcelain is one of the materials of choice for restoration where esthetics is of concern, but has a considerable potentials of wear. The wear of enamel is variable when opposed by different porcelain systems and surface conditions, and the exposed dentine and opaque porcelain due to clinical failure is expected to have high potentials of wear. The purpose of this study was to investigate the wear effects of self-glazed, polished incisal porcelain. polished dentine and opaque porcelain against human enamel in the laboratory by use of a pin-on-disk type wear tester. 4 types of dental porcelain($Vita-{\Omega}$, Ceramco-II, Vintage powder $Vita-{\alpha}$ of In-Ceram system) and type IV gold alloy as cotrol group were used for test specimens. Intact buccal cusps of maxillary premolar were used for enamel specimens, and the cusp converged to a point and was devoid of visible abrasion, caries, decalcification. The upper part was the cusp of a maxillary premolar and the lower part was a porcelain specimen. The enamel wear was deter-mined by weighing the cusp before and after each test. Surface profilometer was used to quantitate wear of the porcelain specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows : 1 Self-glazed porcelain produced more enamel wear than polished porcelain, especially the enamel wear of $Vita-{\alpha}$ self-glazed porcelain was 3.2 times more than that of other groups. 2. Opaque porcelain produced least porcelain wear, $Vita-{\alpha}$ self-glazed porcelain produce greatest porcelain wear, but there was no statistically significant difference between the groups(p>0.05). 3. The enamel wear of dentine porcelain was 3.8 times more than that of polished inisal porcelain(p<0.05), and the enamel wear of opaque porcelain was 1.9 times more than that of polished inisal porcelain, but there was no statistically significant difference between the groups(p>0.05) 4. Overglazed porcelain produced less enamel wear than self-glazed porcelain, and more enamel wear than polished porcelain, but there was no statistically significant difference between the groups(P>0.05). 5. The hardness number of $Vita-{\Omega}$ dentine and Ceramco-II opaque porcelain was larger, but that of Vintage dentine and $Vita-{\alpha}$ self-glazed porcelain was similar to other groups. 6. Examination of SEM photographs revealed that overglazed porcelain had smoother surface than self-glazed porcelain, and self-glazed porcelain had smoother surface than polished porcelain. Much polishing scratches and larger porosities were observed on the opaque porcelain specimen, and much polishing scratchess and small porosities were observed on the dentine porcelain specimen.