• 열처리공학회지
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• 제9권4호
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• pp.289-299
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• 1996

This study has been performed to investigate into some effects of power density and traverse speed of laser beam on the microstructure, hardness and residual stress of AISI 4140 treated by laser surface hardening technique. Optical micrograph has shown that large martensite and a small amount of retained austenite in outermost surface layer and fine lath martensite in inner surface hardened layer are formed under the condition of a given power density and traverse speed. Hardness measurements have revealed that as the power density increases at a given 2.0m/min of the traverse speed, the maximum hardness values of outermost surface hardened layer is increased from Hv=635 to Hv=670. X-ray analysis for residual stress has exhibited that low compressive residual stress values are obtained in center point of the cress section of surface hardened layer with in mid point between the edge and the center point, about 1.5mm from the center point, due simply to a difference in self-quenching rate. It has been shown that the higher the power density at a given traverse speed and the olwer the traverse speed at a given power density, the more the compressive residual stress values are increased due to an increase in the input heat of laser beam.

• 동의생리병리학회지
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• 제17권5호
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• pp.1141-1146
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• 2003

In order to investigate different and original theories on pathology of eyes from the past main etiology of fire and heat, two texts of Si-sheng-xin-yuan written by Huang Yuan Yu and Eui-gam-jung-ma written by Lee Gyu Jun are selected and analysed in terms of pathology and prescription. Huang explained that diseases of the eyes are usually born of functional disorders of spleen and stomach(脾胃升降失調) accompanied with turbidity change of energy and blood(氣血淸濁變化). In the meantime, Lee described that the diseases are made from disorders of activities of essence, spirit, energy and blood stored in 5 viscera. So following them, the main point of treatment for the diseases of eyes is to restore and clarify the stagnated gastrointestinal(GI) function, or to supply the clear essence and blood to eyes respectively. Also they have same opinions that the fire and heat are the secondary symptoms of the optical diseases. Therefore Huang focused on cleaning the phlegm and leaking the moisture of GI tract to treat those symptoms, and Lee emphasized on nourishing essential energy of kidney and liver on the other hand. Although they preferred to use radical therapy than symptomatic one. But it can be deduced that Huang's theory is more positive and direct therapy and Lee's one is more basic but indirect treatment.

• 정보저장시스템학회논문집
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• 제11권1호
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• pp.1-5
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• 2015

The selective frequency analysis method is suggested in the holographic data storage system with the nyquist aperture to reduce the size of hologram. The image filter was designed with many different methods to improve the bit error rate caused by the nyquist aperture. In previous the methods of image restoration for HDS, an iteration time and a highly precise point spread function were necessary. In this paper, we describe the optical system with analytic method. Thereby, we expect our result help the researchers to design the filter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1367-1368
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• 2007

We prepared Zinc Oxide thin films introducing Ag layer on glass substrates at room temperature by using facing targets sputtering (FTS) method. In order to obtain good electrical properties, Ag layer was introduced. Ag with various thickness of thin films were used as intermediate layers. The electrical, optical and crystallographic properties of thin films were investigated by Four-Point probe, UV/VIS spectrometer and XRD. From the results, we could confirm that the thickness of Ag layer changes the electrical and optical performances of the multilayers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.433-434
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• 2007

We prepared ZnO thin films coating Ag on glass substrates at room temperature by using facing targets sputtering (FTS) method. ZnO thin films were deposited with same conditions. Ag with various thickness of thin films were used as intermediate layers. The electrical, optical and crystallographic properties of thin films were investigated by Four-Point probe, UV/VIS spectrometer and XRD. From the results, we could confirm that the thickness of Ag layer changes the electrical and optical performances of the multilayers.

• 대한전자공학회논문지TC
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• 제42권5호
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• pp.1-4
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• 2005

가입자 망에서의 음성, 데이터 및 영상 등 복합 서비스를 위한 대역폭 요구를 충족시키기 위해서 연구 개발되는 EPON에 대한 전반적인 개요와 EPON의 전송 제어 방식인 MPCP에 대해서 간략하게 설명하고, EPON에서 하향 데이터에 대한 대역 제한에 대한 필요성과 하향 데이터 대역 제한을 하기 위한 방법을 제시 하였다

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.653-658
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• 2003

This study is represented a method to give connect to optical cable from accident site and reviewed the method to transmission a moving image to control centre by real time, following the study of image transmission method in copper cable section where is a main line of railroad communication. Concept of network is studied to use cable and equipment effectively, and it's also reviewed technology of digital image transmission system and image evaluation methods, in spite of the pixel of camera and monitor resolution determine quality of image when moving image transferring by point to point. In addition, this study is reviewed checks and considerations of image transmission equipment (codec) with various transmission methods in room test, and then examined and analyzed wire/wireless combined transmission methods at wayside.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.98-98
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• 1999

Highly transparent and conducting tin-doped indium oxide (ITO) films were deposited on polycarbonate substrate by ion-assited deposition. Low substrate temperature (<10$0^{\circ}C$) was maintained during deposition to prevent the polycarbonate substrate from be deformed. The influence of ion beam energy, ion current density, and tin doping, on the structural, electrical and optical properties of deposited films was investigated. Indium oxide and tin-doped indium oxide (9 wt% SnO2) sources were evaporated with assisting ionized oxygen in high vacuum chamber at a pressure of 2$\times$10-5 torr and deposition temperature was varied from room temperature to 10$0^{\circ}C$. Oxygen gas was ionized and accelerated by cold hallow-cathode type ion gun at oxygen flow rate of 1 sccm(ml/min). Ion bea potential and ion current of oxygen ions was changed from 0 to 700 V and from 0.54 to 1.62 $\mu$A. The change of microstructure of deposited films was examined by XRD and SEM. The electrical resistivity and optical transmittance were measured by four-point porbe and conventional spectrophotometer. From the results of spectrophotometer, both the refractive index and the extinction coefficient were derived.

• 한국안광학회지
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• 제21권3호
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• pp.159-171
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• 2016

목적: 서울특별시와 6대광역시의 안경원과 안과의원에 대한 의료서비스 접근성에 대해 연구조사 하였다. 방법: 소상공인시장진흥공단에서 제공하는 2016년 6월 기준 상권정보시스템을 활용하여 서울특별시와 6대광역시의 인구수와 가구 수, 안경원과 안과의원 개설 수 그리고 부동산(아파트) 기준시가를 통해 의료접근도 및 상권분석을 하였으며, SPSS 18.0 통계프로그램을 통해 비교분석하였다. 결과: 안경원의 업소 당 가구 수와 인구수가 가장 높은 곳은 인천광역시(가구수 2,227/인구수 5,723) 그리고 가장 낮은 곳은 광주광역시(1,146/2,979)였으며, 안과의원의 업소 당 가구 수와 인구수가 가장 높은 곳은 광주광역시(24,612/63,987) 그리고 가장 낮은 곳은 서울특별시(10,021/24,432)로 나타났다. 업소 당 가구 수가 낮은 곳은 소비자와 환자의 입장에서는 의료접근성이 높은 곳이지만, 안경원과 안과의 입장에서 수익성의 문제에 의해 경쟁이 치열한 곳으로 큰 어려움이 있을 것으로 판단된다. 안경원과 안과의 입장에서는 경쟁의 치열함으로 인해 치열의 큰 어려움이 있을 것으로 판단된다. 결론: 의료의 중심은 소비자와 환자의 입장에서 이루어져야 하며, 언제 어디서든지 원하는 시점에 가장 원활한 서비스를 받을 수 있는 의료시스템의 구축되어 있어야 한다. 그러나 서울을 비롯한 대부분 광역시의 공통적인 특징은 해당 지역 내에서도 유동성과 상업성이 고려된 지역에 편중되어 안경원 및 안과의원의 밀집되어 있었고 이로 인해 의료 접근도와 서비스가 불균형이 더욱 진행되고 있었다. 이를 해결하기 위해 인구수의 비율에 따른 안경원의 적절한 배치와 지역사회의 안 의료 방향에 대한 균형점을 찾는 산학의 깊은 연구가 필요할 것으로 판단된다.

• 한국통신학회논문지
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• 제38B권2호
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• pp.130-139
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• 2013

최근 풍력 발전 단지가 대형화 해상화됨에 따라 이를 모니터링하고 제어하기 위한 통신망의 중요성이 높아지고 있다. 본 논문에서는 해상 풍력 단지에서 사용하는 기존 Ethernet 기반의 통신망의 문제점인 지연시간, 데이터 처리 오버헤드 및 풍력 발전기간 데이터 전송의 공평성 문제를 해결하기 위하여 EPON(Ethernet Passive Optical Network) 기반의 통신망 구조를 제안하고 성능 평가를 수행한다. 제안한 구조는 OLT(Optical Line Terminal)를 중앙 제어 센터에 설치하고 해상의 풍력 발전기에 ONU(Optical Network Unit)를 설치하여 점 대 다점 통신망을 구성하는 토폴로지이다. EPON 기반 토폴로지는 수동소자를 사용함으로써 망 구성 비용이 저렴하고 관리가 용이하며 높은 신뢰성과 데이터 전송의 공평성을 보장할 수 있다. 제안한 통신망 구조의 성능을 평가하기 위하여 OPNET Modeler를 이용하여 IEC 61850 표준을 기반으로 한 풍력단지를 모델링한다. 시뮬레이션 결과는 기존 이더넷 기반의 통신망과 지연시간, 오버헤드 및 전송의 공평성 관점에서 비교 분석한다.