주기적 신호를 이용한 단일모드 광섬유의 상호 위상변조 해석

이종형,Lee, Jong-Hyung 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.12

단일모드 광섬유를 사용한 WDM 시스템에서 CPM에 의한 성능저하를 이론적으로 분석하기 위해 펌프-프로브 구조에서 펌프신호가 주기적이라고 가정하였다. 주기적 펌프신호는 '0'과 '1'이 교대로 발생하는 경우를 모델링한 것으로 CPM에 의한 EOP를 이론적으로 예측할 수 있게 한다. 유도된 이론적 결과를 수치해석 결과와 비교하였으며, 그 결과 표준 단일모드 광섬유를 사용한 경우는 넓은 영역의 채널 간격 ${\Delta}f$에 대해 유도된 이론식이 수치해석의 결과와 잘 일치하고 분산천이 광섬유를 사용한 경우는 ${\Delta}f$>100GHz 에서 일치하였다. 분산천이 광섬유를 사용하여 ${\Delta}f$<100GHz 인 경우는 CPM뿐만 아니라 FWM에 의한 성능저하가 두드러지므로 이론적 결과와 수치 해석의 결과 사이의 편차가 증가한다. 펌브-프로브 구조가 광섬유의 비선형성중 CPM의 영향을 주로 분석하기 위한 것이므로 이 결과는 예상대로 이다. The pump-probe scheme is used to analyze the cross-phase modulation penalty of a single-mode fiber in a WDM system. The pump signal is assumed to be a periodically modulated input like a raised sinusoidal. The periodic signal models an alternating bit sequence, and leads to an analytical expression of CPM penalty which is measured by EOP. The derived expression shows good agreement with numerical results in conventional single-mode fiber systems over a wide range of channel spacing, ${\Delta}f$. In dispersion-shifted fiber systems when ${\Delta}f$ < 100GHz, the derived expression shows increased discrepancy with the numerical results due to the increased FWM. This is not a surprising because the pump-probe scheme is used to analyze system performance degradation due to CPM.

NRZ 방식을 이용한 40Gbps WDM 시스템의 최적화

이종형,한대현,이용재,최병윤,Lee, Jong-Hyung,Han, Dae-Hyun,Lee, Yong-Jae,Choi, Byeong-Yoon 한국정보통신학회 2008 한국정보통신학회논문지 Vol.12 No.10

40Gbps로 동작하는 WDM시스템의 성능 최적화를 위해 그 특성을 numerical simulation 을 통해 알아 보았다. 이때 광섬유는 가장 널리 사용되고 있는 표준 단일 모드로 가정하였으며, 변조 방식 역시 가장 간단하면서 널리 사용되고 있는 NRZ 방식을 사용하였다. 이는 40Gbps의 새로운 시스템을 설치하는 경우보다 기존의 시스템에서 각 채널의 전송율을 40Gbps로 증가시킴으로써 최종 전송용량을 향상시킬 경우를 고려하였기 때문이다. 수신단의 필터(optical 및 electrical) 특성을 최적화하고 색분산 보상 및 입력신호 크기의 최적화를 통해 기존에 매설된 단일 모드광섬유로 약 480km (BER < 10-15)까지 전송할 수 있음을 알았다. 또한 시스템의 성능이 EDFA의 ASE 노이즈 특성에 의해 크게 제한 될 때, 수신단의 광 필터는 삽입 손실이 5dB 이상 크지 않다면, Gaussian모양보다는 Flattop 모양의 광 필터가 성능개선에 더 유리함을 알 수 있었다. 40Gbps WDMSystems have been studied by numerical simulation to optimize their performance. Standard single mode fiber is assumed, and the most popular modulation format, NRZ, is used for the study. These assumptions are valid when existing WDM systems are required to upgrade their performance to 40Gbps. It is shown that the standard single mode fiber can transmit optical signals over 4800 (BER < 10-15) by optimizing optical and electrical filter characteristics at the receiver and by compensation of dispersion. In addition, when the system performance is mainly limited by ASE noise of EDFAs, it is found that flattop-shaped optical filter at the receiver gives a better result than Gaussian-shaped filter unless the insertion loss of the optical filter is larger than 5dB.

동계 소결마찰재 개발에 관한 연구

이종형,최병호,김정,Lee, Jong-Hyung,Choi, Byung-Ho,Kim, Jeong 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.1

In a study on the development of Cu-based sintered friction materials, the specimens pressed with various compacting pressures $(3-6 ton/cm^2/)$ have been evaluated to find the optimum condition of compacting pressure. As compacting pressure increased up to $(5 ton/cm^2/)$, mechanical properties such as density, hardness, bending strength, wear and coefficient of friction, etc. improved remarkably, but up to 6 ton/cm$^{2}$, decreased slightly because of traps of gases and water vapors in specimen. Disk assembly composed of 12 pieces of Cu-based friction materials has been compared with one of asbestos-and nonasbestos-based friction materials. In dynamic and driving tests to find burst spin strength, corrosion area rate and friction properties, etc., Cu-based sintered friction materials showed better properties than the others, especially in severe conditions because oxides such as $Cu_2O; and; SnO_2$ in the friction surface of friction materials were formed.

A Study on the Friction and Wear of Bronze Sintered Friction Materials

이종형,박무수,양성현,Lee, Jong-Hyung,Park, Moo-Soo,Yang, Seong-Hyeon The Korean Society of Manufacturing Process Engine 2004 한국기계가공학회지 Vol.3 No.3

The effect of bronze sintered friction materials on frictional and mechanical properties is studied with the content(8~18 wt,%) and shapes (flake and irregular) of graphite that is used as solid lubricants to meet diverse characteristics such as low coefficient of friction, low wear rate and high bending strength. The content and shapes of graphite are optimized by statistical experiments. Friction test was carried out measure friction coefficient, temperature dependence and wear rate. As a result of experiments, the density, hardness and bending strength with a shape of flake graphite are lower and decrease rapidly than that of Irregular, as the content of graphite increases up to 18 wt% Aftei friction test, coefficient of friction is 0.3~0 4 and wear rate is $0.32{\sim}2.98{\times}10^{-7}cm^3/kg{\cdot}m$. When the content of graphite increases, coefficient of friction increases In a shape of flake graphite and decreases in a shape of irregular graphite.

조대조직을 갖는 비자성강의 피로균열진전거동

이종형,최성대,정선환,권현규,양성현,Lee, Jong-Hyung,Choi, Seong-Dae,Cheong, Seon-Hwan,Kwon, Hyun-Kyu,Yang, Seong-Hyeon 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.4

High manganese steel was maintained stability of Non-Magnetics performance. Fatigue tests were carried out under constant stress amplitude, using a non-magnetic high manganese steel. The fatigue crack growth mechanism of the high manganese steel was clarified from results such as observation of crack growth path and fracture surface. The result of getting this study was shown as following: 1) Remarkably ${\Delta}Kth$ of the high manganese steel is big with about 3 times of the general steel product. 2) In the low ${\Delta}K$ value region, da/dN is dependent on Kmax, and in the high ${\Delta}K$ value region, it is dependent on ${\Delta}Keff$. The reason of this behavior is crack closure due to fracture surface roughness and fretting oxide. 3) It seems to ease the stress concentration of crack tip crack growth behavior in the ${\Delta}Kth$ vicinity by the generation of the secondary crack.

탄소강의 피로균열에 대한 탄소성파괴 해석에 관한 연구

이종형 ( Jong-hyung Lee ),정형식 ( Hyung-sik Jeong ),유덕상 ( Duck-sang Yoo ),김영문 ( Young-moon Kim ) 한국산업융합학회 2006 한국산업융합학회 논문집 Vol.9 No.2

This paper is to provide some of the analysis procedures of the FAD(Failure Assessment Diagram), which is applied th the safety test of the atomic pressure vessels and other structures. Harrison proposed R-6 Diagram, and Bloom developed the method of DPFAD(Deformation Plasticty Failure Assessment Diagram). Analysis of J-integration of the plastic materials give the failure test curve for the materials with serious work hardening effect. J value was obtained form both FEM(Finite Element Mothod) and the experiment using compact type specimen for J=JIC, and the results were compared. In this study, the results of analysis using DPFAD and the factors affecting DPFAD in Static fatigue and fracture were reviewed. It was shown that the concept of DPFAD can be applied to test the safety of the structures.

2CAVITY 다이캐스팅을 이용한 자동차 VALVE HOUSING의 기계적 특성 해석

이종형 ( Jong-hyung Lee ),윤종철 ( Jong-cheul Yoon ),유덕상 ( Duck-sang Yoo ),이창헌 ( Chang-heon Lee ),하홍배 ( Hong-bae Ha ) 한국산업융합학회 2006 한국산업융합학회 논문집 Vol.9 No.2

Valve-housing parts in car steering system is a part of steering system and then take charge of the main functions for car steering system to reduce driver's handling-force. Recently it is still not developed reliable casting for many cars, so it produce as a Gravity casting which is more than triple for producing cost in Korea. In this research, we had conducted that 350t aluminum die casting is superior to mechanical property from established over 500t or not for Valve-housing, a parts of steering system which were produced as a cast-iron product and the most suitable conditions to extruding as die casting.

클러치 마스터 실린더의 소재변화에 따른 내부응력에 관한 연구

이종형(Jong-Hyung Lee),이상철(Sang-Cheol Lee),이춘곤(Chun-Kon Lee),권영신(Yung-Shin Kwon),이창헌(Chang-Heon Yi),황용기(Yong-Ki Hwang),소윤섭(Yoo-Sub So) 한국산업융합학회 2006 한국산업응용학회 학술대회 논문집 Vol.- No.-

Special quality of automobile CMC(clutch master cylinder) and analyzed aluminum, plastic material comparison. Efficiency of plastic master cylinder can modularize higher, light weight anger of parts, several piece parts by single parts, prove NVH(Noise, Vibration, Harshness) than aluminum master cylinder as analysis result. Also, structure is easy simplicity, exchange, maintenance costs can be reduced and decrease environmental pollution because recycling is superior. According as content of glass fiber increases, mechanical properties of matter of material increase equally and glass fiber changed variously by condition on manufacturing process. Through comparison analysis with Plastic Body development connection site, did verification.

Socio-cultural and geographic factors affecting infant Low Birth Weight (LBW) for Korean immigrant women in New York City

Jong Hyung Lee(이종형),Sara McLafferty(새라 맥래퍼티),Jawon Lee(이자원) 성신여자대학교 한국여성연구소 2014 여성연구논총 Vol.15 No.-

이 연구의 목적은 이민 여성의 인종 밀집도 가설을 조사하고 한국이민 여성이 낳은 저체중 출생아의 위험도가 지역적 혹은 지리적으로 어떻게 차이가 나는지, 그리고 사회 경제적 변수들과 인종 밀집도와 어떠한 관계가 있는지를 분석하고자 하였다. 연구의 세 가지 주요 목적은 : (1) 뉴욕시에 거주하고 있는 한국 이민 여성의 생식건강 결과와 그들의 밀집도와의 관계를 조사하고; (2) 저체중 출생의 위험도와 사회 경제적 상태의 지표들 사이의 상관 관계를 분석하고; (3) 저체중 출생과 지역 특성 사이의 상관 관계를 조사하는 것이다. 지리 정보 시스템 (GIS)은 뉴욕 도시내 인구조사 표준지역별 한국이민 여성들의 분포와 이들의 밀집도를 시각화하는 데 사용되었다. 인구 통계학적 및 사회 경제적 변수 (독립 변수) 자료들을 사용하여 저체중 출생아(종속 변수)의 변화를 설명하고 예측하기 위해 로지스틱 회귀 분석이 수행되었다. 종속 변수를 저체중 출생으로 설정했을 때, 세 개의 변수들, 즉 건강 클리닉에 근접, 결혼 여부의 상태, 인종밀집도는 뉴욕시에 거주하고 있는 한인 이민 여성들이 저체중 출생아를 낳는 결과를 설명하는 데 있어서 유의한 것으로 밝혀졌다. 하지만 임신 기간으로 회귀 분석을 수행했을 때, 연령만이 출생 결과에 유의한 영향을 미치는 것으로 밝혀졌다. The purpose of this research is to investigate the ethnic density hypothesis for immigrant women and analyze geographic variation in the risk of low birth weight for infants born to Korean immigrant women and its relation to the socio-economic variables and ethnic density. The three main objectives of the study are: (1) to investigate the relationship between ethnic density and reproductive health outcomes for Korean immigrant women in New York City; (2) to analyze the correlations between low birth weight risk and indices of socio-economic status; and (3) to examine the correlations between low birth weight and neighborhood characteristics. Geographic Information System (GIS) is used to describe the general pattern of low birth weight and to visualize the density of the Korean immigrant women. Logistic regression analysis is performed to explain and predict the variability of low birth weight using data of the demographic and socio-economic variables. With low birth weight as the dependent variable, three variables, namely proximity to health clinic, marital status, and ethnic density are significant in explaining this birth outcome in New York City.

고압다이캐스팅을 이용한 자동차 밸브하우징의 주조방안 및 기계적 특성에 관한 연구

이종형 ( Jong-hyung Lee ),이창헌 ( Chang-heon Yi ),이상중 ( Sang-joong Lee ) 한국산업융합학회 2006 한국산업융합학회 논문집 Vol.9 No.4

Today's automobiles are changing into miniaturization and light weight for saving natural resources and energies. In order to raise the sufficiency of fuel consumption, new mechanism and components are required. Therefore, the expectations on the new materials are very high. Especially, Al materials are widely used to reduce the motors weight. Al using in automobiles is mostly casting material, and the material is developing rapidly in step with technical innovation. Al die casting has become an important field, as we are turning today's motor into light weight. One of the parts in steering system, valve housing, plays a role to reduce the operating effort of drivers. If valve housing being a part of steering system is produced by gravity casting, the space that manufacturing equipments are installed will be increased, and more energies and workers will be needed