ONU 파워 균등화 기능을 갖는 E-PON 송수신기에 관한 연구

임충환,정인권,박영일 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.7

HVDC 해저케이블의 연속허용전류 계산에 관한 연구

임충환,박흥석,문채주,Lim, Chung-Hwan,Park, Hung-Sok,Moon, Chae-Joo 한국전자통신학회 2022 한국전자통신학회 논문지 Vol.17 No.5

The growing integration of intermittent renewable sources like offshore wind energy increases the need for transferring electric energy over long distances, which may include sea crossings. One of the solutions available for bulk electric power transmission across large distances encompassing wide and deep sea is using HVDC submarine power cables. However, there are no standards or research related to the calculation of the continuous allowable current with various ocean conditions of a DC power cable that does not have an alternating magnetic field. In this study, assuming the typical two types of subsea cable models and two areas of the south coast and the west coast marine conditions, a continuous allowable current simulation of DC cables was performed. As a simulation result, the DC cable continuous allowable current find out the gradient reduction characteristics based on subsea base depth.

Development of Compacted Vermicular Graphite Cast Iron for Railway Brake Discs

임충환,구병춘 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.2

In the case of employing brake discs as a key component of mechanical brake equipment, the initiation of thermal cracking owing to repetitive thermal shock generated during braking may potentially lead to higher maintenance costs, worsened braking performance, and greater risk of railway accidents. The purpose of this study is to gain basic data to facilitate application of compacted vermicular (C. V.) graphite cast iron to brake discs in order to obtain high thermal crack resistance and improved lifetime. To this end, this study developed three types of C. V. graphite cast iron with differing content of key elements, including Ni, Cr,and Mo. Each test specimen underwent numerous tests for evaluation of materials characteristics, and the results were compared with those obtained for existing materials. The test results show that the thermal fatigue lifetime of material C is nearly double that of the conventional material. This demonstrates the suitability of material C as a material for brake discs in mid- to high-speed railway vehicles.

위험물 수송 철도차량 탱크의 구조강도 평가방법 개선연구

임충환,구병춘 한국화재소방학회 2008 한국화재소방학회논문지 Vol.22 No.3

In this study, we researched about characteristics of many kinds of tank cars for carrying hazard materials and performed structural strength evaluation using finite element analysis for tank of asphalt tank car to suggest the efficient analysis method that can develop accuracy regarding to haracteristics of tank cars. For this, we analyzed the asphalt tank refer to JIS E 7102 (Design Method for Tanks of Tank Cars). As results, we could show that the maximum stress is applied at the area supported by saddle and the maximum stress is under a criterion suggested from JIS E 7102. Therefore we verified that this asphalt tank car had enough structural strength. 본 연구에서는 현재 위험물 수송용 탱크 화차에 대하여 수행되고 있는 구조해석 방법에 대한 문제점을 보완하기 위하여 국내에서 운행중인 위험물 수송용 탱크차의 종류와 특성을 조사하고 그 중 아스팔트 탱크화차의 비압력식 탱크에 대하여 탱크 화차의 구조적 특성을 고려하는 유한요소법을 이용한 구조적 강도평가 방법을 제시하였고 이를 위하여 JIS E 7102에 기술되어있는 탱크화차의 강도설계를 위한 실차 시험방법 절차를 유한요소법으로 구현하여 해석하였다. 그 결과 탱크를 지지하는 새들과 탱크와의 접촉부에서 최대응력이 발생하였으나 이는 JIS 규격에서 제시하는 평가기준을 초과하지 않았다. 이로써 아스팔트 탱크화차의 탱크는 충분한 구조적 강도를 갖고 있다는 결과를 도출하였다.

ONU 파워 균등화 기능을 갖는 E-PON 송수신기에 관한 연구

임충환,정인권,박영일 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.7A

E-PON 시스템의 ONU 출력 광신호 크기가 가입자에 따라 많은 차이를 보이는 경우 OLT 수신단의 규격이 까다로워지고, 전체 PON 시스템의 안정된 동작을 보장할 수 없게 된다. 이러한 문제를 해결하기 위해 OLT 수신단에서 ONU 각 채널의 송신 광신호 크기를 검출하고 이로부터 제어신호를 이용해 등록된 ONU 채널들의 크기를 일정하게 조절하는 방식을 제안하고 실험을 통해 이를 확인하였다. 또한 ONU 송신단에는 디지털 APC 회로를 이용하여 전송 신호 존재 시 수 bit 이내에 LD를 동작하고, 전송 신호가 없을 경우 LD 구동전류를 차단함으로써 다른 ONU의 전송을 보장하며, 소비전력을 감소할 수 있도록 하였다. When optical signal power of ONU differs from each other the requirements of an OLT receiver becomes strict and the stable operation of a total PON system can't be obtained. To solve this problem each ONU channel's signal power is measured at the OLT side and control signals to equalize them are generated and sent to each ONU. The proposed scheme is tested after implementation A digital APC circuit is proposed and tested so that it can start or stop LD operation without delay. It helps other ONU to transmit signals without interference and to reduce consuming power.

아스팔트 수송용 철도차량 탱크의 구조강도 평가

임충환(C. H. Lim),구병춘(B. C. Goo) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

We studied on the characteristics of many kinds of tank cars carrying hazard materials and performed structural strength evaluation for tank of asphalt tank car using finite element analysis. We analyzed the tank strength according to JIS E 7102(Design Method for Tanks of Tank Cars). It was found that the maximum stress obtained at the area supported by the saddle is much lower than the yield stress and the criteria of JIS E 7102.

MGT(Micro Gas Turbine) 터빈 휠 최적설계 연구

임충환(C. H. Lim),박필제(P. J. Park),김병화(B. H. Kim),김종기(J. G. Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

The MGT(Micro Gas Turbine) generator has risen up as an alternative for other generators in accordance with the global tendency in the energy distribution, and the markets has been also expanding. The turbine wheel is a key component of the MGT generators and it is required to be designed for increasing operating temperature. In this paper, we studied the effects of shape factors to structural performance of a radial turbine rotor in CHP(Combined Heat and Power) MGT we are developing. For this study, we performed the parametric analysis about thickness of back plate, area of scallops and blade fillet radius which affect with concentrated stress on the turbine rotor using FEM and RSM(Response Surface Method). Then we designed the turbine rotor has optimized shape and we carried out additional analysis to select a proper material for MGT operational conditions.

제동디스크 소재의 내열성 비교시험방법 연구

임충환(Lim Choong-Hwan),구병춘(Goo Byeong-Choon) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

In the braking of a railroad car, mechanical brake systems using wheel tread and brake disk are applied as well as electrical brake systems by regenerator and rheostat. During disk braking, kinetic energy of the vehicle is converted into thermal energy through friction between disk and brake pad. And it causes high temperature concentration and generates thermal crack on the brake disk surface. In this study, comparative test process for heat-resistance of candidate materials was designed for development of brake disk materials having high heat-resistance. We also verified the efficiency of the process by experiments using conventional brake disk materials.

철도차량용 CV 흑연 주철 제동디스크의 열피로 특성 평가

임충환(Choonghwan Lim),이웅(Ung Lee),구병춘(Byeongchoon Goo) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11

In the disc-pad brake system for railway or automobile, the initiation of thermal cracks which occur by frictional heating on the disc surface affects their maintainability as well as braking performance. In this respect, it is need to develop the new brake disc material which improved on resistance for thermal crack initiation and propagation. In this study, we performed the thermal fatigue test to compare heat-resistance among the candidate materials as one of development procedures of CV(Compacted Vermicular) cast iron brake disc for railway. And microstructural observation using metallurgical microscope was also carried out to evaluate the effect of graphites characteristics such as their size and distribution.

철도차량 제동디스크 소재 열충격 실험에 대한 피로해석

임충환(Choong-Hwan Lim),구병춘(Byeong-Choon Goo) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7

During braking of railway vehicles the repetitive thermal shock leads to thermal cracks on disc surface, and the lifetime of brake disc is dependent on the number of trimming works for removing these thermal cracks. Many tries for development of high heat resistant brake disc to extend the disc life and to warrant reliable braking performance has been continued. In present study, we carry out the computational fatigue analysis for thermal fatigue test in three candidate materials which were made to develop new high heat resistant material. Using FEM, we simulate thermal fatigue test in three candidate materials and conventional disc material. We then estimate the number of cycle to thermal crack initiation based on data from mechanical fatigue tests, and the results are compared with each material. For each material, the correction factor for Nf-40 which is the number of cycles when crack over 40?㎛ was observed in thermal fatigue test is decided. From this study, we can verify the performance of thermal fatigue test system and suggest a qualitatively comparative method for heat resistance by FEM analysis of thermal shocking phenomenon.