2.4 GHz 무선LAN 전자파 환경대책용 전파흡수체 개발

윤상길(Sang Gil Yoon) 김대훈(Dae Hun Kim) 박수훈(Soo Hoon Park),김동일 (Dong Il Kim) 한국항해항만학회 2009 한국항해항만학회지 Vol.33 No.3

본 논문에서는 실내 무선LAN 환경에서 발생하는 다중반사에 의한 통신속도 저하 및 데이터 손실과 같은 문제점을 해결하기 위한 전파흡수체를 설계하였다. 먼저 자성손실 재료인 Sendust와 지지재인 CPE(Chlorinated Polyethylene)조성비별 전파흡수체 샘플을 제작하였고, 각 샘플의 재료정수를 이용하여 시뮬레이션 한 결과, 최적의 조성비가 Sendust : CPE = 80 : 20 wt.% 임을 확인하였다. 그리고 시뮬레이션 결과를 토대로 전파흡수체를 실제작하였다. 제작된 전파흡수체의 측정 결과 시뮬레이션 결과와 잘 일치하였으며, 제작된 전파흡수체는 두께 3.2 5mm 조성비 Sendust : CPE = 80 : 20 wt.%이며, 중심주파수 2.4 GHz에서 19dB의 전파흡수 특성을 보였다. In this paper, the EM wave absorber was designed and fabricated for improvement of Wireless LAN environment at 2.4 GHz. We fabricated several samples in different composition ratios of Sendust and CPE(Chlorinated Polyethylene). Absorption abilities were simulated in accordance with different thicknesses of the prepared absorbers and changed complex relative permittivity and permeability due to composition ratio. The mixing ratio of Sendust and CPE was searched as 80: 20 wt.% by experiments and simulation Then the EM wave absorber was fabricated and tested using the simulated data. As a result, the EM wave absorber was fabricated based on simulated data. Simulated and measured results agreed well. As a result, the developed EM wave absorber with thickness of 3.25 mm has absorption ability of 19 dB at 2.4 GHz.

지상파 위성동시재송신 정책의 논쟁과정과 그 평가

윤상길(Sang-Gil Yoon),홍종윤(Jong-Yoon Hong) 한국방송학회 2004 방송통신연구 Vol.- No.59

Sendust와 Mn-Zn Ferrite를 이용한 PCB로부터의 전자파 방사 억제용 전파흡수체 개발

윤상길(Sang-Gil Yoon),김동일(Dong Il Kim),송영만(Young-Man Song),박수훈(Soo-Hoon Park) 한국전자파학회 2008 한국전자파학회논문지 Vol.19 No.2

본 논문에서는 Sendust와 Mn-Zn ferrite를 이용하여 2.4 ㎓ ISM 대역 PCB 노이즈 제거용 전파흡수체를 설계 및 제작하였다. Sendust와 Mn-Zn ferrite를 바인더인 CPE와 혼합하여 조성비별 전파흡수체 샘플을 제작하였고, 이를 분석한 결과 최적의 조성비가 Sendust : Mn-Zn ferrte : CPE=70:5:20 wt.%임을 확인하였다. 전파흡수체 샘플로부터 계산되어진 재료 정수를 이용하여 두께에 따른 흡수능의 변화를 시뮬레이션 하였으며, 시뮬레이션 결과를 토대로 전파흡수체를 실제작하여 전파 흡수능을 비교, 분석하였다. 그 결과, 시뮬레이션 결과와 실측정 결과는 잘 일치하였으며, 중심 주파수 2.4 ㎓에서 흡수능 5.4 ㏈, 1.4~4.1 ㎓ 대역에서 3 ㏈ 이상의 흡수능을 보였으며, 이때 두께는 0.85 ㎜이었다. In this paper, we designed and fabricated the EM wave absorber consists of Sendust and Mn-Zn ferrite for suppressing EM wave noise from PCB in ISM(Industrial, Scientific and Medical) band of 2.4 ㎓. We fabricated several samples in different ratios of Sendust to Mn-Zn ferrite with CPE(Chlorinated Ploy-ethylene) as binder and confirmed that optimum composition ratio of absorbing materials was Sendust : Mn-Zn ferrite : CPE=70:5:20 wt.%. The absorbing abilities were simulated according to different thickness of EM wave absorber as the function of material constants calculated by measured data. Measured absorption ability was analyzed and compared with simulated result. The simulated result agree well with the measured ones. As a result, the developed EM wave absorber with thickness of 0.85 ㎜ has absorption ability of 5.4 ㏈ at 2.4 ㎓ and over 3 ㏈ in frequency rage of 1.4~4.1 ㎓.

일제시기 京城전화 네트워크의 공간적 배치

윤상길(Yoon, Sang-Gil) 서울시립대학교 서울학연구소 2009 서울학연구 Vol.- No.34

The purpose of this article is to look at technological and institutional elements of telephone system, and spatial distribution of telephone system in Seoul during colonial period. For this purpose, technological and institutional elements of telephone system was regarded as °Æenvironment of use°Ø which determine user°Øs behavior, and its political characteristics were investigated. In chapter 2, the political and military characteristics of technological telephone system are founded from the fact that the Government-General of Korea(GGK) had depended on primarily alterations of telecommunication mode, instead of depending on of extensive installation of telecommunication facilities, as essential measure of coping with diverse problems, such as contradiction between low-grade of transmission technology and increasing telecommunication demand. For example, GGK depended primarily on °Æsimultaneous telegraphy and telephony°Ø mode. Also, institutions related to telephone subscription, phone call, and charge of telephone fee were established in the direction of keeping a firm on not so much irregular phone call as regular call. Telephone system of this sorts had been diffused throughout Seoul city. In chapter 3 and chapter 4, the transfiguration of local telephone service area in Seoul and its spatial bias were examined. At first, local telephone service area in Seoul was changed roughly three times during colonial period. Local telephone service area began to be kept in order in 1910s, and was established systematically as telephone exchange system consisting of one head office and two branch office in 1923. And one more branch office was added in eastern area of Seoul in 1942. Even though there were more or less alterations, spatial distribution of telephone facilities in Seoul was hardly changed. Local service area of head office, covering business zone and Japanese place of residence, had exceeding 50% of the number of total telephone. If including Yong-San branch office covering military zone, the proportion was over 70%. On the other side, Gwang-Hwa-Moon branch office covering Korean place of residence about 30%. As a result, Korean people had to go to usually post office or public telephone nearby their place of residence. In sum, spatial structure of telephone diffusion in colonial Seoul was under bias toward nation.

거래활동 기반 회계자동분개처리시스템 설계 및 구현

윤상길 ( Gil-sang Yoon ) 한국정보처리학회 2015 한국정보처리학회 학술대회논문집 Vol.22 No.1

국내의 회계프로그램은 일반적으로 거래발생주의에 따라 차변과 대변을 기록하는 복식부기구조의 전표입력을 통한 분개처리 기반으로 이루어져 있다. 이러한 프로그램은 사용자로 하여금 일정수준의 회계지식을 요구한다. 그로 인해 일반 중소기업처럼 회계담당직원이 없는 경우에는 회계전문가에게 의뢰를 하거나 도움을 받아야 한다. 본 연구에서는 재무보고서의 원천이 되는 전표발행에 있어서 거래사실만을 입력하면 복식부기의 기준에 맞게 자동분개처리 되어 전표서비스를 제공해줄 수 있는 시스템을 설계 및 구현한 결과를 보여준다. 이는 사용자들이 회계시스템을 쉽게 접근할 수 있는 회계프로그램 개발의 새로운 방향을 제시할 것으로 본다.

1920,30년대 인천부(仁川府) 전화 미디어의 확산구조

윤상길(Yoon, Sang-gil) 인천대학교 인천학연구원 2009 인천학연구 Vol.11 No.-

The purpose of this article is to look at the spatial diffusion of telephone system in In-cheon during 1920~30s. For this purpose, this article discussed historical development of technological and institutional elements of telephone system during colonial period. Telephone enterprises established by the Government-General of Korea(GGK) in an administrative district of In-cheon was stagnated by two primary factor. This two primary factor was as follows. The first factor was problems of telephone administration such as the adjustment of partitions in telephone subscription district. Actually, the definite adjustment of partitions in telephone subscription district of In-cheon was accomplished in 1919. The second factor was technological problems such as obsolete telephone equipments. Telephone sets over seven thousand couldn't be accommodated before a single magneto switchboard was changed into a multiple magneto switchboard in December, 1923. Nonetheless, the diffusion of telephone among Japanese people was accomplished in comparatively fast pace. Japanese people owned telephone at the rate of three or four household to one. But, the diffusion of telephone among Korean people was very slow, showing a ratio of one hundred household to one. Also, the diffusion of telephone in In-cheon of 1920~30s was biased in terms of occupational distribution. About 90% of telephone owner were merchants and industrialists. Also about 33~4% of telephone owner of merchants and industrialists were forwarding agents, grain brokers, grain millers, and restaurant owner. On the other hand, the ethno-biased diffusion of telephone was intertwined with the space-biased diffusion. Overall spatial diffusion of telephone in In-cheon was accomplished in two ways. One was pattern of diffusing without particular rules in a densely populated district of telephone owner. The other was pattern of diffusing according a main road in a loosely populated district of telephone owner. As a result, telephones of Korean people were mainly located in regions such as 'Naeri'(內里), 'Yongri'(龍里), 'Oeri'(外 里), where Korean rich person lived. telephones of Japanese people were diffused with a form of a concentric circle. Central region of this concentric circle was as follows: 'Hang-Jeong'(港町), 'Hae-An-Jeong'(海岸町), 'Bon-Jeong' (本町), 'Joong-Jung'(仲町), 'Bin-Jeong'(濱町), 'Shin-Jeong'(新町), 'Goong-Jeong'(宮 町).

실내 무선 LAN 전자파 환경 대책용 전파 흡수체에 관한 연구

윤상길(Sang Gil Yoon),김동일(Dong Il Kim),이대희(Dae Hee Lee),최창묵(Chang-Mook Choi) 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.11

최근, 실내 무선 LAN은 편리함과 용도의 다양성으로 인해 가정이나 사무실 등에서 사용이 증대되고 있으며, IEEE 802.11a와 IEEE 802.11b에 명시되어 있는 바와 같이 5.2 ㎓와 2.4 ㎓의 주파수 대역을 사용하고 있다. 그러나 실내 공간에서 무선 LAN 기기들을 사용할 경우, 벽ㆍ천정ㆍ바닥ㆍ책상 등에 의해서 반사파가 발생하고, 이들 반사파의 다중 반사는 통신 속도 저하와 데이터 손실과 같은 문제점을 발생시킨다. 이러한 문제점은 전파 흡수체를 사용하여 해결하는 것이 가장 효과적이다. 따라서 본 논문에서는 MnZn-ferrite, sendust, carbon을 이용하여 전파 흡수체를 제작하였으며, 지지재로는 CPE(Chlorinated Polyethylene)를 이용하였다. 제작된 전파 흡수체 측정 결과, 조성비가 MnZn-ferrite : sendust : CPE=64 : 16 : 20 wt.%일 때, 두께가 3.7 ㎜인 전파 흡수체가 2.4 ㎓에서 17 ㏈의 전파 흡수 특성을 보였고, 조성비가 MnZn-ferrite : carbon : CPE=40 : 15 : 45 wt.%일 때, 두께가 3.8 ㎜인 전파 흡수체가 5.2 ㎓에서 23 ㏈의 전파 흡수 특성을 보였다. Recently, wireless LAN are often applied in home or office because of its various of convenience. Frequency rage of wireless LAN specified by IEEE 802.11a is at 5.2 ㎓ and IEEE 802.11b is 2.4 ㎓. But in offices with wireless LAN devices, reflection of waves against walls, ceilings, floors and desks made of metal creates multipath problems that reduce communication speed and lose data. These problems can be solved by using EM wave absorber. In this paper, we designed and fabricated EM wave absorbers using MnZn-ferrite, sendust, carbon and CPE(Chlorinated Polyethylene). The EM wave absorber with the ratio of MnZn-Ferrite : sendust : CPE=64 : 16 : 20 wt.% has thickness of 3.7 ㎜ and absorption ability more than 17 ㏈ at 2.4 ㎓ and the EM wave absorber with the ratio of MnZnferrite : carbon : CPE=40 : 15 : 45 wt.% has thickness of 3.8 ㎜ and absorption ability more than 23 ㏈ at 5.2 ㎓.

Solenoid 전동기의 냉각을 위한 수치해석적 연구

정민채(Min-Chae Jung),윤상길(Sang Gil Yoon),윤동진(Dong Jin Yoon),서정세(Jeong-Se Suh) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.4

In this study, the temperature distribution and heat transfer characteristics of each component in a solenoid motor system were numerically investigated when heat is generated by the steel pad attached to the solenoid ring of the motor. It was found that the internal airflow was complicated by the inflow velocity of air and the rotation of guide rollers and solenoid rings. Based on the numerical results, the tendency for temperature changes in the steel panel was lower due to the contact of the cooling air in the front in the rotational direction, and the peak temperature was at the front of the center. In particular, it was confirmed that as the air inflow rate was increased, the temperature was reduced due to strong convection. The temperature of the iron plate pad was decreased as the convective heat transfer coefficient was linearly increased with increasing airflow around the solenoid ring. In addition, the temperature of the iron plate panel was rapidly increased with increasing heat generation.

Back Analysis of Field Measurements Around the Tunnel with the Application of Genetic Algorithms

김선명,윤지선,전덕찬,윤상길,Kim Sun-Myung,Yoon Ji-Sun,Jun Duk-Chan,Yoon Sang-Gil Korean Geotechnical Society 2004 한국지반공학회논문집 Vol.20 No.7

In this study, the back analysis program was developed by applying the genetic algorithm, one of artificial intelligence fields, to the direct method. The optimization process which has influence on the efficiency of the direct method was modulated with genetic algorithm. On conditions that the displacement computed by forward analysis for a certain rock mass model was the same as the displacement measured at the tunnel section, back analysis was executed to verify the validity of the program. Usefulness of the program was confirmed by comparing relative errors calculated by back analysis, which is carried out under the same rock mass conditions as analysis model of Gens et at (1987), one of back analysis case in the past. We estimated the total displacement occurring by tunnelling with the crown settlement and convergence measured at the working faces in three tunnel sites of Kyungbu Express railway. Those data measured at the working face are used for back analysis as the input data after confidence test. As the results of the back analysis, we comprehended the tendency of tunnel behaviors with comparing the respective deformation characteristics obtained by the measurement at the working face and by back analysis. Also the usefulness and applicability of the back analysis program developed in this study were verified. 본 논문에서는 역해석 방법 중 직접법의 성능에 큰 영향을 미치는 최적화 과정을 인공지능의 한 기법인 유전자알고리즘을 이용하여 역해석 프로그램을 구성하였다. 유전자 알고리즘 및 역해석 기법의 효용성을 검증하기 위하여 과거 역해석 연구 사례 중의 하나인 Gens et al(1987)과 동일한 암반조건을 가진 모델에 대한 역해석을 실시하여 그 결과를 비교${\cdot}$검토하였다. 경부고속철도 터널 현장의 내공변위 및 천단침하에 대한 계측자료로부터 최종 내공변위의 예측함수를 결정하는 방법으로 터널의 총 변위를 분석하였다. 이를 역해석에 필요한 입력자료로 활용하여 역해석을 실시하고 터널 주변 암반의 거동을 반영할 수 있는 지반의 특성치를 구하였다. 각 현장 시험에서 얻어진 지반의 특성치와 비교한 결과 본 연구에서 적용된 유전자 알고리즘을 이용한 역해석 방법이 유의한 수준의 결과를 도출하고 있다는 사실을 확인하였다.

언론학 교육에 있어서 실무와 이론의 이분법을 넘어서 : 서울대 언론학 교육 30년을 중심으로

강명구(Kang Myung-Koo),윤상길(Yoon Sang-Gil) 서울대학교 언론정보연구소 2005 언론정보연구 Vol.42 No.1

지식정보사회로 이행하는 사회적 변화, 정보테크놀로지와 산업의 변화, 저널리즘의 변화 등 언론정보학을 둘러싼 사회환경의 변화는 언론학 교육의 목표와 실천에 커다란 도전이라고 할 수 있다. 이 글의 목적은 서울대학교 언론정보학 학부 교육 30년을 되짚어 봄으로써, 자기 혁신을 어떻게 이룰 것인가를 성찰하는데 있다. 이를 위해 이 글은 지난 30년간 커리큘럼의 변화와 그 거리 큘럼에 대해 학생들이 실제로 어떤 과목을 수강하였는지를 실증적으로 분석하고 기존의 언론학교육을 둘러싼 논쟁, 특히 실무와 이론교육에 대한 논쟁을 살펴보았다. 그 결과, 실무교육에 대해서는 현장이 요구하는 인재의 능력이 무엇인지에 관해 보다 정확하게 규정할 필요가 있으며, 이론중심 교육에 대해서도 대학원에 진학할 학문후속세대를 위한 커리큘럼과 언론과 정보통신 산업 현장으로 진출할 인력을 위한 이론중심 교육을 명확히 구분하고 그 내용을 고민할 필요가 있음을 주장하였다. 그리고 이를 실현하기 위한 하나의 대안으로 실무와 이론교육을 통합적으로 사고하는 형성적 학습과 현장지식 (hands-on knowledge)의 교육을 제시하고자 하였다. Rapidly changing social environments surrounding communication and media studies, such as the advent of a knowledge-information society, changes in information technologies and information industries and changes of journalism, demand responding changes in the realm of communication education. By reviewing curriculum changes of the Department of Communication at Seoul National University between 1975 and 2004, this study aims to discover a way to innovate communication education. This study reviews disputes on the roles of communication education, whether it should more focus on practical knowledge or theoretical knowledge. After comparing pros and cons of educational focus of the two opposing camps, this thesis suggests an alternative way to perceive communication education, which emphasizes 'formative learning' and 'hands-on knowledge' as its important elements. By doing so, this study will offer a way to integrate the two opposing perspectives and overcome the dichotomy.