Y_2O_3 함량과 소결조건에 따른 상압소결 AlN 세라믹스의 열전도도 고찰

나상문,고신일,이상진 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.5

Aluminum nitride (AlN) has excellent thermal conductivity, whereas it has some disadvantage such as low sinterability. In this study, the effects of sintering additive content and sintering condition on thermal conductivity of pressureless sintered AlN ceramics were examined on the variables of 1~3 wt% sintering additive (Y_2O_3) content at 1900℃ in N_2 atmosphere with holding time of 2~10 h. All AlN specimens showed higher thermal conductivity as the Y_2O_3 content and holding time increase. The formation of secondary phases (yttrium aluminates) by reaction of Y_2O_3 and Al_2O_3 from AlN surface promoted the thermal conductivity of AlN specimens, because the secondary phases could reduce the oxygen contents in AlN lattice. Also, thermal conductivity was increased by long sintering time because of the uniform distribution and the elimination of the secondary phases at the grain boundary by the evaporation effect during long holding time. A carbothermal reduction reaction was also affected on the thermal conductivity. The thermal conductivity of AlN specimens sintered at 1900℃ for 10 h showed 130~200W/mK according to the content of sintering additive.

Y₂O₃ 함량과 소결조건에 따른 상압소결 AlN 세라믹스의 열전도도 고찰

나상문,고신일,이상진,Na, Sang-Moon,Go, Shin-Il,Lee, Sang-Jin 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.5

Aluminum nitride (AlN) has excellent thermal conductivity, whereas it has some disadvantage such as low sinterability. In this study, the effects of sintering additive content and sintering condition on thermal conductivity of pressureless sintered AlN ceramics were examined on the variables of 1~3 wt% sintering additive ($Y_2O_3$) content at $1900^{\circ}C$ in $N_2$ atmosphere with holding time of 2~10 h. All AlN specimens showed higher thermal conductivity as the $Y_2O_3$ content and holding time increase. The formation of secondary phases (yttrium aluminates) by reaction of $Y_2O_3$ and $Al_2O_3$ from AlN surface promoted the thermal conductivity of AlN specimens, because the secondary phases could reduce the oxygen contents in AlN lattice. Also, thermal conductivity was increased by long sintering time because of the uniform distribution and the elimination of the secondary phases at the grain boundary by the evaporation effect during long holding time. A carbothermal reduction reaction was also affected on the thermal conductivity. The thermal conductivity of AlN specimens sintered at $1900^{\circ}C$ for 10 h showed 130~200W/mK according to the content of sintering additive.

리튬용액침투법에 의한 내열충격성이 향상된 세라믹 제조

나상문,이상진 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.2

Porcelain with high thermal shock resistance was successfully fabricated by a lithium solution infiltration method with a lithium hydroxide solution. Lithium hydroxide solutions having various lithium concentrations were infiltrated into pre-sintered porcelain bodies. The porcelain sample infiltrated by the 9 wt% lithium solution and heat treated at 1250oC for 1 h showed a low thermal expansion coefficient of 1.0 × 10−6/oC with excellent thermal shock resistance. The highly thermally resistant porcelain had a welldeveloped β-spodumene phase with the general phases observed in porcelain. Furthermore, the porcelain showed a denser structure of 2.41 g/cm 3sintering density and excellent whiteness in comparison with commercial thermally resistible porcelains. The lithium hydroxide in the samples readily reacted with moisture, and liquid phase reactants were formed during the fabrication process. In the case of an excess amount of lithium in the sample body, the lithium reactants were forced to the surface and re-crystallized at the surface, leaving large pores beneath the surface. These phenomena resulted in an irregular structure in the surface area and led to cracking in samples subjected to a thermal shock test.

호텔종사원이 지각하는 고용불안정성이 직무스트레스와 조직시민행동에 미치는 영향에 있어 마음챙김의 조절효과

나상문 ( Sangmoon Na ),최우성 ( Woosung Choi ) 관광경영학회 2018 관광경영연구 Vol.82 No.-

This study is focused on the relationship between job stress and organization citizenship behavior which is the key of operating hotel enterprises especially at individual and organizational level rather than focused on the relationship between job instability and various variables as before. After a close review on moderating effects of mindfulness, the variable that manages effect relationship between employment unstableness and job stress, this study will proceed to cover the effect relationship between job stress and organization citizenship behavior. Empirical analysis to achieve the purpose of this study has concluded the following results: First, the higher the perception of employment unstableness, the higher the job stress and turnover intentions. In this regard, hotel enterprises should devote themselves: to build up trust in the organization to lower employment unstableness perceived by the employees, to raise job satisfaction by using training programs that can build teamwork or interactive activities that enable interaction among employees, to reduce job instabilities by paying higher attention to employees and welfare problems, and to give employees various opportunities such as career development at an organizational level. Secondly, job stress was not influence on organization citizenship behavior. Thirdly, mindfulness is found to have moderating effects on influence of employment unstableness on job stress. Therefore it would be helpful for hotel enterprises running programs to support employees to spend time looking back on themselves or meditate.

호텔종사원이 지각하는 고용불안정성이 이직의도와 조직시민행동에 미치는 영향에 관한 연구: 마음챙김의 조절효과

최우성,나상문,라채일 한국관광산업학회 2018 Tourism Research Vol.43 No.4

This study is focused on the relationship between turnover intentions which is the key of operating hotel enterprises especially at individual and organizational level rather than focused on the relationship between job instability and various variables as before. After a close review on moderating effects of mindfulness, the variable that manages effect relationship between employment unstableness and turnover intentions, this study will proceed to cover the effect relationship between turnover intentions and organization citizenship behavior. Empirical analysis to achieve the purpose of this study has concluded the following results: First, the higher the perception of employment unstableness, the higher turnover intentions. In this regard, hotel enterprises should devote themselves: to build up trust in the organization to lower employment unstableness perceived by the employees, to raise job satisfaction by using training programs that can build teamwork or interactive activities that enable interaction among employees, to reduce job instabilities by paying higher attention to employees and welfare problems, and to give employees various opportunities such as career development at an organizational level. Secondly, it appears that the organization citizenship behavior becomes lower with higher perception of turnover intentions. In order to increase organization citizenship behavior which takes on a role of representative variable of management performance, turnover intentions should be kept unperceptive. In particular, perception in employment unstableness should be kept lower according to the results of this study. Thirdly, mindfulness is found to have moderating effects on influence of employment unstableness on turnover intentions. Therefore it would be helpful for hotel enterprises running programs to support employees to spend time looking back on themselves or meditate. 본 연구에서는 기존의 연구들과 동일하게 고용 불안정성과 다양한 변수들의 관계를 보기보다는 개인 및 조직 차원에서 호텔기업의 운영과 관련하여 매우 중요한 이직의도의 관계를 규명하고자 한다. 그리고 고용 불안정성이 이직의도에 미치는 영향관계에서 이들 관계를 조절할 수 있는 변수로 마음 챙김 이라는 변수를 통해 조절효과를 보고자하며, 마지막으로, 이직의도가 조직시민행동에 미치는 영향관계를 살펴보고자 한다. 이러한 연구목적을 달성하기 위해 호텔 종사원들을 대상으로 실증 분석한 결과 다음과 같은 결과가 도출되었다. 첫째, 고용 불안정성에 대해 높게 지각할수록 이직의도가 높은 것으로 나타났다. 이에 호텔 기업에서는 종사원들이 지각하는 고용 불안정성을 낮추기 위해 조직에 대한 신뢰를 쌓을 수 있도록 해야 할 것이다. 또한 조직 구성원들 간의 상호 작용을 할 수 있는 업무 외 활동이나 팀워크를 조성할 수 있는 교육훈련과 같은 프로그램의 활용을 통해 종사원들의 전반적 직무만족 수준을 높이고 복지문제와 종사원에 대한 관심을 좀 더 제고하여 종사원들의 고용불안정을 줄이도록 하며, 조직적 차원에서 종사원들에게도 발전 가능성에 관한 다양한 기회(경력개발 등)를 주도록 노력해야 할 것이다. 둘째, 이직의도에 대해 높게 지각하면 조직시민행동이 낮아지는 것으로 나타났다. 이에 경영성과를 대리하는 변수로서 역할을 하는 조직시민행동을 높이기 위해서는 이직의도를 지각하지 않도록 해야 할 것이다. 특히 본 연구의 결과와 관련하여 고용 불안정성에 대해 높게 지각하지 않도록 해야 할 것이다. 셋째, 마음 챙김은 고용 불안정성이 이직의도에 미치는 영향에 있어 조절효과를 보이는 것으로 나타났다. 이에 호텔기업에서는 마음 챙김 정도를 증대시키기 위해 일정시간 동안 명상이나 자기 자신을 돌아볼 수 있는 시간을 할애 할 수 있도록 지원할 수 있는 프로그램 운영이 필요하다.

중국유학생들의 전공 선택 동기가 전공만족에 미치는 영향에 있어 대학생활적응의 조절효과

왕용 ( Wang Long ),최우성 ( Choi Woo-sung ),나상문 ( Na Sang-moon ) 한국관광산업학회 2016 Tourism Research Vol.41 No.3

본 연구에서는 유학생들의 전공 선택 동기에 대한 연구의 필요성을 바탕으로 현재 한국에서 외국인 유학생 가운데 가장 많은 수를 차지하고 있는 중국인 유학생의 전공 선택 동기와 전공만족 간의 관계를 파악하고 중국 유학생들의 대학생활적응은 전공 선택 동기와 전공만족 간의 관계에 대한 조절효과를 규명하고자 하였다. 실증분석 결과 다음과 같은 연구결과가 도출되었다. 먼저 중국 유학생의 전공 선택 동기와 전공만족의 관계를 검증한 것으로 분석결과 전공 선택 동기 중 내재적 동기만이 전공만족에 정(+)의 방향으로 영향을 미치는 것으로 나타났다. 즉 내재적 동기에 대해 높게 지각하면 전공만족도가 높아진다고 볼 수 있다. 하지만 전공 선택 동기 중 외재적 동기는 통계적으로 유의한 영향을 미치지 않는 것으로 나타났다. 다음으로 대학생활 적응의 조절효과에 있어서는 중국 유학생의 대학생활 적응에 따라 전공 선택 동기가 전공만족도에 미치는 영향력의 차이를 검증한 결과 내재적동기에 대해 높게 지각하면 전공만족이 높아지며 대학생활 적응이 조절효과를 보이면서 전공만족을 높게 하는 것으로 나타났다. 이러한 연구결과를 바탕으로 유학생들에게 단순 한국대학에 입학을 시킬때 단순 한국어능력시험을 통해 선발하기 보다는 적성 및 흥미도 테스트 및 졸업 후 어떠한 직무에서 일을 할 예정이며, 전공을 선택한 동기에 대한 충분한 사전 검증을 통해 학생들을 선발해야 할 것이다. 또한 유학생들이 자신감을 가질 수 있도록 쉽게 달성 가능한 목표를 설정하여 자신감을 가질 수있도록 하거나 한국학생들과 문화적 교류 및 공동생활을 할 수 있는 프로그램 제시를 통해 심리 및 육체적으로 한국문화나 생활에 적응할 수 있도록 지원해야 할 것이며, 유학생들의 교육적응을 높이기위한 대학차원의 노력이 필요하다고 할 수 있다. This study aims to understand the relationship between major selection motivation and major satisfaction of Chinese students who occupy the large share of foreign students in Korea based on the necessity of study for major selection motivation of foreign students, and verify the control effect of relationship between major selection motivation and major satisfaction for the adjustment of college life of Chinese students. The deducted study results following analysis result of actual proof are as follows. First, when analyzing the relationship between major selection motivation and major satisfaction of Chinese students, the immanent motivation among major selection motivation had positive influence to major satisfaction. In other words, the higher the immanent motivation is, the higher the major satisfaction is. However, the extrinsic motivation did not have significant influence statistically. Next, as for the control effect to college life adjustment, when verifying the difference of influence of major selection motivation to major satisfaction regarding the college life adjustment of Chinese students, the higher one aware immanent motivation, the higher the major satisfaction is, and showed control effect to college life adjustment and showed higher major satisfaction. Based on the study result, the students must be chosen by not just simple TOPIK(Test of Proficiency in Korean) test but conduct advance verification such as aptitude and interest test, career path they will pursue after graduation, or the major selection motivation. Also, to give confidence to the foreign students, the schools need to put their effort the support students to adjust into Korean culture and life physically and psychologically by providing program that they can set attainable goal to have confidence, and to enjoy cultural exchange and community activity with Korean students to ultimately increase the educational adjustment of foreign students.

프릿을 이용한 다공질 SiC 세라믹스의 저온 제조 공정 및 물성

채수호,김영욱,송인혁,김해두,배지수,나상문,김승일,Chae, Su-Ho,Kim, Young-Wook,Song, In-Hyuck,Kim, Hai-Doo,Bae, Ji-Soo,Na, Sang-Moon,Kim, Seung-Il 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.5

Porous frit-bonded SiC ceramics were successfully prepared at a temperature as low as $800^{\circ}C$ from SiC, frit, and microbeads (glass or polymer). The effects of SiC starting particle size and microbead addition on microstructure, porosity, and flexural strength were investigated. The addition of hollow glass microbead improved the strength of frit-bonded SiC ceramics without the loss of porosity by acting additional binder phase between SiC grains. The 65 ${\mu}m$-sized SiC resulted in lower porosity and higher strength than 50 ${\mu}m$-sized SiC because of higher packing density. Typical flexural strengths of frit-bonded SiC were 23 MPa at 46% porosity and 19 MPa at 49% porosity.

다공질 지르코니아 세라믹스의 기공율 제어

채수호,엄정혜,김영욱,송인혁,김해두,배지수,나상문,김승일,Chae, Su-Ho,Eom, Jung-Hye,Kim, Young-Wook,Song, In-Hyuek,Kim, Hai-Doo,Bae, Ji-Soo,Na, Sang-Moon,Kim, Seung-Il 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.1

A simple pressing process using zirconia and microbead for fabricating porous zirconia ceramics is demonstrated. Effects of microbead content and sintering temperature on microstructure, porosity, compressive and flexural strengths were investigated in the processing of porous zirconia ceramics using microbead as a pore former. By controlling the microbead content and the sintering temperature, it was possible to produce porous zirconia ceramics with porosities ranging from 43% to 70%. Typical compressive and flexural strength values at ${\sim}50%$ porosity were ${\sim}150\;MPa$ and ${\sim}35\;MPa$, respectively.

국내산 현무암과 맥반석으로부터 무기질 연속섬유 제조와 그 특성

김재근 ( Jae Keun Kim ),배지수 ( Ji Soo Bae ),나상문 ( Sang Moon Na ),김승일 ( Seung Il Kim ),진용준 ( Young Jun Jin ) 한국복합재료학회 2006 Composites research Vol.19 No.6

취업스트레스가 대학생활적응에 미치는 영향에 있어 회복탄력성의 조절효과에 대한 연구: 관광관련전공 대학생을 중심으로

방한승 ( Bang Han-seung ),최우성 ( Choi Woo-sung ),나상문 ( Na Sang-moon ),조형규 ( Cho Hyeong-gyu ) 한국관광산업학회 2017 Tourism Research Vol.42 No.2

현대사회 속에서 사람들은 수많은 급격한 변화를 경험하고, 그러한 환경에 적응하면서 살아가야 한다. 특히, 적응의 문제는 인생의 발달 단계에서 어느 시기나 중요하지만, 대학생의 시기는 과도기적시점이며, 특히 현재의 적응이 이후의 적응체계에까지 중요한 영향을 미치기 때문에 대학생 시기의 적응은 더욱 더 고려되어야 할 필요가 있다. 이에 본 연구에서는 진로장벽과 취업스트레스의 결과 대학생활적응에 어떠한 영향을 미치는지를 연구하였다. 또한 이들 관계에서 대학생활적응에 정적인 영향을 미치는 변인으로 회복탄력성을 설정하여 취업스트레스와 대학생활적응의 관계에서 어떠한 조절효과를 보이는지를 연구하였다. 연구결과 다음과 같은 결과가 도출되었다. 첫째, 취업스트레스는 대학생활적응을 낮게 하는 것으로 나타났다. 특히 학교환경과 학업스트레스가 대학생활적응을 낮게 하는 것으로 나타났다. 이에 학교환경과 관련하여 대학의 인지도는 취업과 관련하여 사회에서 매우 중요한 역할을 한다. 하지만 현대에는 직무능력중심과 같이 스펙보다는 직무와 관련된 어떠한 능력을 가지고 있느냐가 취업의 성공과 관련성이 높다, 이에 자신이 다니고 있는 대학의 인지도보다는 자신의 원하는 취업처에서 요구하는 직무와 관련된 기술이나 자격이 무엇인지를 파악하여 이에 적합한 노력을 해야 할 것이다. 둘째, 취업스트레스와 대학생활적응에서 회복탄력성이 조절효과를 보이는 것으로 나타났다. 이에 학생들의 회복탄력성 강화를 통한 대학생활적응을 잘 할 수 있도록 해야 할 것이다. In modern society, people have to experience a lot of radical changes and have to live adapting to such environments. In particular, the adaptation issue is important at any stage in the developmental stages of life, but the stage of college students is a transitional period, and the adaptation to college student period should be considered further, especially since current adaptation has important impact on subsequent adaptation systems. Therefore, in this research, the effect of employment stress on college life adaptation was studied. In addition, resilience as a variable which buffers the effect of employment stress in the relationship between employment stress and college life adaptation. The results of the research were generated as follows. First, employment stress was shown to lower adaptation to college life. Especially, college environment and academic stress were found to lower adaptability to college life. Therefore, the college recognition in relation to the school environment plays a very important role in society in relation to employment. However, in modern age, it is highly relevant to the success of employment what ability they have in relation to the relevant jobs such as performance ability rather than `spec`s. Therefore, it is necessary to identify what skills and qualifications are required related to the job by the desired organization and to make efforts fit for it, rather than the recognition of the college that they attend. Second, resilience was shown to have moderating effect on employment stress and college life adaptation. In other words, it is found that, though the perception about employment stress is high, if the perception about resilience is also high, the adaptation to college life gets high. Therefore, students will have to be able to adapt well to college life by strengthening their resilience.