http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : 최현우(Choi, Hyounwoo) (검색결과 171 건)
- 무료
- 기관 내 무료
- 유료
-
온도 변화에 따른 YAG 및 Silicate형광체 기반 백색 LED의 광특성 변화에 대한 연구
최현우,고재현,Choi, Hyun-Woo,Ko, Jae-Hyeon 한국광학회 2013 한국광학회지 Vol.24 No.3
본 논문에서는 YAG:Ce와 $(Sr,Ba)_2SiO4:Eu$ 등 두 종류의 형광체를 사용하여 백색 LED를 제작하고 온도변화에 따라 각각의 백색 LED의 발광 특성이 어떻게 변하는지 조사하였다. 상온에서 $80^{\circ}C$ 사이의 구간에서 측정된 두 백색 LED의 발광 스펙트럼을 분석하기 위해 asymmetric double sigmoidal 함수를 활용하였다. 이 함수를 백색 LED의 청색 발광 및 황색 발광 피크에 적용해서 각 피크의 중심파장과 진폭, 반치폭 및 비대칭성을 온도의 함수로 구하였다. 그 결과 온도가 증가할수록 청색 피크의 중심파장이 장파장 쪽으로 천이되고 황색피크의 중심파장이 단파장 쪽으로 천이되며 비대칭성 또한 증가한다는 것을 확인할 수 있었다. 이러한 결과는 두 백색 LED의 색도변화에 반영되었는데, 실리케이트계 형광체 기반 LED의 색도 변화가 더 큼을 알 수 있었다. 발광효율 역시 온도가 증가할수록 크게 떨어지는 것을 볼 수 있었는데 YAG 형광체 기반 LED의 발광효율 저하 폭이 더 적음을 확인하였다. 이상의 결과는 YAG 형광체 기반 백색 LED가 실리케이트계 형광체 기반 LED에 비해 색도안정성, 발광효율, 연색지수 측면에서 더 뛰어나다는 것을 의미한다. Two white light emitting diodes(LEDs) were fabricated by using two kinds of yellow phosphor, YAG:Ce and $(Sr,Ba)_2SiO4:Eu$, and their spectroscopic properties were analyzed as a function of temperature from room temperature to $80^{\circ}C$. The asymmetric double sigmoidal function was applied to both blue and yellow peaks of the emitting spectrum to obtain the center wavelength, the amplitude, the half width, and the skewness parameters. According to this analysis, the center wavelength of the blue peak shifted to longer wavelength while that of the yellow peak shifted to shorter wavelength. In addition, some of the skewness parameters were found to increase upon heating, which indicates that spectrum asymmetry becomes enhanced at higher temperatures. The changes in the color coordinates and the luminous efficacy were larger for the case of silicate-based white LED. These results suggest that the silicate-based white LED is inferior to the YAG-based white LED from the viewpoint of color stability, efficacy and color rendering index.
-
황색 형광체의 종류에 따른 백색 LED 광원의 발광 특성 분석
최현우,고재현,Choi, Hyun-Woo,Ko, Jae-Hyeon 한국광학회 2013 한국광학회지 Vol.24 No.2
본 논문에서는 청색 LED 칩에 YAG:Ce와 $(Sr,Ba)_2SiO_4:Eu$ 등 두 종류의 황색 형광체를 적용해서 제작한 백색 LED의 발광특성을 비교, 분석하였다. 두 백색 LED의 발광 스펙트럼의 특성을 분석하기 위한 수학적 함수 형태로써 Asymmetric double sigmoidal 함수를 적용할 수 있음을 확인하였고 이를 통해 발광 스펙트럼을 구성하는 피크들의 중심파장, 폭, 비대칭성에 대한 정보를 정량적으로 구해서 비교하였다. 분석 결과 실리케이트계 형광체의 발광 스펙트럼 폭이 YAG 형광체에 비해 더 좁아 연색지수의 측면에서 불리한 반면 구동전류에 따른 색도 안정성의 측면에서는 더 유리하다는 것을 확인하였다. 두 백색 LED의 발광효율은 구동전류의 증가에 따라 단조감소하였는데, 실리케이트 형광체 기반 LED의 발광효율이 YAG형광체 기반 LED에 비해 약 10~12 lm/W 정도 작음을 확인하였다. In this paper, two white light emitting diodes(LEDs) were manufactured by using two kinds of yellow phosphor, YAG:Ce and $(Sr,Ba)_2SiO_4:Eu$, and their spectroscopic properties were compared and analyzed. We found that the asymmetric double sigmoidal function can be applied to both white LEDs to obtain the center wavelength, the half width, and the skewness parameters. According to this analysis, the half width of the emitting spectrum of silicate phosphor was smaller than that of YAG phosphor, indicating smaller color rendering index. However, the silicate phosphor exhibited better color stability depending on the driving current than the YAG phosphor. The current dependence of the luminous efficacy of both white LEDs was investigated, which showed that efficacy decreased monotonically with current. The efficacy of the silicate-based white LED was lower than that of the YAG-based LED by about 10~12 lm/W.
-
Lithium disilicate 유리의 입자크기에 따른 결정화 기구
최현우,윤혜원,양용석,윤수종,Choi, Hyun Woo,Yoon, Hae Won,Yang, Yong Suk,Yoon, Su Jong 한국재료학회 2016 한국재료학회지 Vol.26 No.1
We have investigated the crystallization mechanism of the lithium disilicate ($Li_2O-2SiO_2$, LSO) glass particles with different sizes by isothermal and non-isothermal processes. The LSO glass was fabricated by rapid quenching of melt. X-ray diffraction and differential scanning calorimetry measurements were performed. Different crystallization models of Johnson-Mehl-Avrami, modified Ozawa and Arrhenius were adopted to analyze the thermal measurements. The activation energy E and the Avrami exponent n, which describe a crystallization mechanism, were obtained for three different glass particle sizes. Values of E and n for the glass particle with size under $45{\mu}m$, $75{\sim}106{\mu}m$, and $125{\sim}150{\mu}m$, were 2.28 eV, 2.21 eV, 2.19 eV, and ~1.5 for the isothermal process, respectively. Those values for the non-isothermal process were 2.4 eV, 2.3 eV, 2.2 eV, and ~1.3, for the isothermal process, respectively. The obtained values of the crystallization parameters indicate that the crystallization occurs through the decreasing nucleation rate with a diffusion controlled growth, irrespective to the particle sizes. It is also concluded that the smaller glass particles require the higher heat absorption to be crystallized.
-
S-P3P: P3P 표준을 반영한 보안 프로토콜 설계 및 분석
최현우,장현수,고광선,김구수,엄영익,Choi, Hyun-Woo,Jang, Hyun-Su,Ko, Kwang-Sun,Kim, Gu-Su,Eom, Young-Ik 한국정보처리학회 2007 정보처리학회논문지 C : 정보통신,정보보안 Vol.14 No.7
P3P(Platform for Privacy Preference) that is used in the World Wide Web is a standard to define and negotiate policies about definition, transmission, collection, and maintenance of personal information. Current P3P standard provides methods that define client personal information protection policy and P3P policy associated with web server. It also provides a method that compares these two policies. The current P3P standard, however, does not handle detail functions for safe transmission of the personal information and data. Also, it does not handle problems that can be induced by the detail functions. In this paper, in order to solve these problems, we propose a Secure P3P(S-P3P) protocol, which is a security protocol for the current P3P standard, offers mutual authentication between the web server and the client, and guarantees integrity and confidentiality of the messages and data. Furthermore, a S-P3P protocol provides non-repudiation on transmission and reception of personal information that is transmitted from the client to the web server. P3P는 웹 서비스 제공자와 사용자 사이에서 사용되는 개인정보의 정의, 전송, 수집, 그리고 유지 등에 대한 정책을 정의하고 협상하기 위한 표준이다. 현재까지 제시된 P3P 표준은 주로 사용자의 개인정보보호 정책과 웹 서버의 P3P 정책을 정의하고 두 정책을 비교하는 방법을 제공하고 있다. 그러나 사용자와 웹 서버 사이의 개인정보 및 데이터의 안전한 전송을 위한 세부 기능과 이 때 발생할 수 있는 문제점에 대해서는 명확하게 제시하고 있지 않다. 이러한 문제점을 해결하기 위해서, 본 논문에서는 Secure P3P(S-P3P) 프로토콜을 제안한다. 제안 프로토콜은 현재의 P3P 표준을 위한 보안 프로토콜로서 웹 서버와 사용자 간의 상호 인증 기능을 제공하고, 전송되는 메시지와 데이터의 무결성과 기밀성을 보장한다. 또한, S-P3P 프로토콜은 사용자로부터 웹 서버에 전송되는 개인정보의 송수신에 대한 부인방지 기능을 제공한다.
-
-
-
일제강점기(日帝强占期) 권업모범장(勸業模範場) 관료(官僚)의 구미(歐美) 파견(派遣) 추이(推移)와 관료(官僚)의 활동(活動)
최현우 ( Choi Hyun-woo ) 동아대학교 석당학술원 2021 石堂論叢 Vol.- No.79
본 논문에서는 일제강점기에 미국ㆍ유럽과 그들의 식민지를 시찰 조사한 권업 모범장 관료의 파견 추이와 그들의 활동을 검토하였다. 조선총독부는 1916년부터 1929년까지 8명의 권업모범장 관료를 파견하였으며, 시찰 조사 분야는 농업정책ㆍ경영, 축산, 면화, 전작, 토양ㆍ비료, 잠업 등에 걸쳐 있었다. 조선총독부는 농업정책의 현안을 해결하고 특정 농업 분야의 전문 인력을 양성하기 위해 해외 출장의 형식으로 권업모범장 관료를 구미에 파견하였다. 이들 관료의 대다수는 권업모범장과 이를 계승한 농사시험장, 조선총독부 농업 부서에서 관련 업무와 연구를 지속하거나, 조선축산협회ㆍ조선농회 등과 같은 관변 단체의 임원으로 활동하였다. 이들은 자신의 정치ㆍ사회적 지위와 전문성을 바탕으로 조선총독부의 농업정책을 정당화하고, 그것을 기술적으로 뒷받침함으로써 효율적인 식민지배체제의 구축과 운영에 영향을 주었다. This paper examines the dispatching trends and their activities of officials from the Agricultural Experiment Station[勸業模範場] of the Chosen Government General[朝鮮總督府] who inspected the United States, Europe and their colonies. Chosen Government General sent eight officials of the Agricultural Experiment Station from 1916 to 1929. The field of inspection investigation covered agricultural policies and management, stock raising, cotton, dty-field farming, soil and fertilizer, sericulture. Chosen Government General sent officials to solve pending agricultural policy issues and to train professionals in certain agricultural fields. The majority of these officials continued their work and research in the gricultural Experiment Station and the agricultural department of the Chosen Government General. They also served as an executive of an agricultural organization. They justified the agricultural policies of the Chosen Government General based on their political and social status and expertise.
-
한국 병역제도의 발전방향 연구 - 외국 병역제도 사례들의 SWOT 분석을 중심으로-
최현우 ( Choi Hyeon-woo ),강원석 ( Kang Won-seok ) 한국군사학회 2018 군사논단 Vol.96 No.-
Since the establishment of the Korean government in 1948, the conscription system has been adopted and it has been maintained to date to take into consideration the actual security threats of North Korea, the potential security threats of neighboring countries such as Russia, Japan and China and the geopolitical conditions of the Korean peninsula. There is a lot of discussion about the introduction of volunteer military system as an alternative to the qualitative development of combat power, but there are real difficulties to consider when introducing volunteer military system. In addition to understanding the internal and external environments of Korea, we tried to seek lessons from SWOT analysis of the military service system in other countries and its process and backgrounds and tried to utilize them in discussing the transition of military service system of Korea. In this study, we analyzed the case of Spain, which has recently been changed to volunteer military system, and Japan, which has been enforcing volunteer military system after World War II, and Turkey, which has maintained the conscription system. Based on this, we tried to set the foundation for discussing the transition of military service system of Korea. By analyzing the internal and external environment of each country separately, we analyzed what was the strength, weakness, opportunity, and threat in enforcing the military service system. In the early 21st century, Spain succeeded in instituting a volunteer military system based on economic growth and political development along with stability of external security environment. Japan armed forces were disbanded by compulsion after World War II defeat. But the army was filled by introducing a volunteer military system because the necessity of strengthening the defense force was increased due to the intensification of the Cold War system including the Korean War, and the public negative awareness on the conscription system was dominant. Turkey has a strong conscription system due to public support for conscription and extreme threats of national security. Korea satisfies certain conditions of nations instituting volunteer military system but we came to the conclusion that it is too early to enforce volunteer military system because securing defense budget and military service resources is weakness and current security threat is serious. However, in the near future, efforts should be made at the national level to meet various prerequisites such as improving the economic level and reducing the threat of security on the Korean peninsula, aiming at stable volunteer military system.
-
-
시민 교육의 관점에 본 한국사 교과서의 사회 구성원 지칭 방식과 한국사 교육의 방향
최현우 ( Choi Hyun-woo ) 역사교육학회 2016 역사교육논집 Vol.61 No.-
There are various terminology about society members of Korean history textbooks. The Korean history textbooks mainly assumed `nation (國民)` and `citizen(市民)` as a independent members of society. Many students think that `nation`, `minjung(民衆)`, `citizen` mean independent members of society. About 30 percents of students selected `citizen`. But they could not explain the meaning of `citizen`. So This thesis critically examined research trends of historical education on democracy and citizen education and sought out the direction of Korean history education for citizen`s education. There is no objective correct answer in the method and purpose of citizen education. We have to think about what the society we desire and we must recognize and solve the challenges to realize this. `citizen` have the practical consciousness and citizen education is to nurture such citizens. History shows the trend of struggle for citizen not only to show what society was formed through process and effort, but also to become citizen. Through this we can explore not only the meaning and qualities of citizens but also the society that future citizens and civil society aim for. In this sense, history education provides the foundation for citizen education, as well as Korean history education. In Korean history education, from the ancient times to the present, a single group assumed to be a so-called `Korean` in Korean history did not exist, but countless groups were transferred and assimilated through the process of war and immigration. We must deal with these facts concretely. And we must reconfirm the reason why a particular group was suppressed nationally and the activities that occurred to resolve it and why the teaching and learning for this is important. Efforts to become members of society with rights and obligations are not limited to specific skin colors and beliefs, even though limited to the democratization struggle since the Korea independence. The change from `national history(國史)` to `Korean history(韓國史)` is related to the nurture of democratic citizens. However, it is true that Korean history education has been limited, such as certain races, areas, beliefs, under the name `Korean`s identity formation`. It`s time to rethink the role and direction of Korean history education for the education of citizens in a situation where globalization, pluralization is progressing rapidly.
DBpia
ScienceON연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
