The effects of matrix aging and residual stress changes on $Avimid^{(R)}$ K3B/IM7 laminates

김형원,Kim, Hyung-Won The Korea Institute of Military Science and Techno 2005 한국군사과학기술학회지 Vol.8 No.3

In this paper, the effects of matrix hygrothermal aging and residual stress changes on $Avimid^{(R)}$ K3B/IM7 laminates in $80^{\circ}C$ water were studied. The factors causing the $80^{\circ}C$ water to degradation of the laminates could be the degradation of the matrix toughness, the change in residual stresses. After 500 hours fully saturated aging of the neat resin, the weight gain was 1.55% increase with the diffusion coefficient $7{\times}10^{-6}m^2/s$ and the fracture toughness was decreased about 41%. After 100 hours fully saturated aging of the $[+45/0/-45/90]_s$ K3B/IM7 laminates in $80^{\circ}C$ water, the weight gain was 0.41% increase with the diffusion coefficient $1{\times}10^{-6}m^2/s$ and the loss of the microcracking fracture toughness was 43.8% of the original toughness. To see whether the residual stress influenced the fracture toughness, two ply $[90^{\circ}/0^{\circ}]$ laminates were put in $80^{\circ}C$ water from 2 hours to 8 hours. The changes in residual stress in 8 hours are less than 3MPa. Because the 3MPa change is not sufficient to degrade the laminates, the main factor to degrade the microcracking fracture toughness was the degradation of the matrix fracture toughness.

The Aging Effect of $Avimid^(R)$ K3B/1M7 Laminates in $80^{\circ}C$ Water

김형원,Kim Hyung-Won 한국추진공학회 2005 한국추진공학회지 Vol.9 No.4

미세균열이 생기기 전 $80^{\circ}C$ 물속에서 침수시간에 따른 $Avimid^(R)$ K3B/IM7 복합재의 습기노화 현상에 관하여 연구하였다. $80^{\circ}C$ 물속에서 복합재의 파괴인성을 저하시키는 요인으로는 수지 파괴인성의 저하나 잔류응력의 변화 그리고 섬유와 수지 사이의 계면 손상이다. $80^{\circ}C$ 물속에서 수지에 습기가 포화되는 시간은 500 시간이며 K3B/IM7복합재에 습기가 포화되는 시간은 100 시간이다. 수지가 500 시간 가속노화한 후 DSC 시험을 한 결과 $T_g$는 1% 이내 증가하였으며, 무게는 $7\times10^{-6}m/s^2$ 확산속도로 1.55% 증가하였다. K3B/IM7복합재에 관하여 물속에서 100시간 지난 후 무게는 $1\times10^{-6}m/s^2$ 확산속도로 0.41% 증가했다. 500 시간 노화한 후 수지의 파괴인성은 41% 저하하였으며 100 시간 노화한 후 ${[+45/0/-45/90]}_s$ K3B/IM7 복합재의 미세균열 파괴인성은 43.8% 감소하였다. 그러므로 $80^{\circ}C$ 수분노화 시험에서 복합재 적층의 파괴인성을 감소시키는 주요 원인은 수지 파괴인성의 저하라고 할 수 있다. The Hygrothermal aging of the laminates of $Avimid^(R)$ K3B/IM7 in $80^{\circ}C$ water was studied as a function of immersion time prior to forming microcracks. The factors causing the $80^{\circ}C$ water to degradation of the laminates could be the degradation of the matrix toughness, the change in residual stresses or the interfacial damage between the fiber and the matrix. The times to saturation in $80^{\circ}C$ water for the laminates and for the neat resin were 100 hours and 500 hours. After 500 hours aging of the neat resin, the glass transition temperature was changed less than 1% by DSC test, and the weight gain was 1.55% increase with the diffusion coefficient $7\times10^{-6}m/s^2$ and the fracture toughness was decreased about 41%. After 100 hours fully saturated aging of the ${[+45/0/-45/90]}_s$ K3B/IM7 laminates in $80^{\circ}C$ water, the weight gain was 0.41% increase with the diffusion coefficient $1\times10^{-6}m/s^2$. In 100 hours, the loss of the fracture toughness of the laminates was 43.8% of the original toughness by the microcracking fracture toughness criterion. Therefore, the main factor to degrade the microcracking toughness of the laminates could be the degradation of the matrix fracture toughness.

토지리턴제 용지공급방식의 개선방안 연구

김형원(Kim, Hyung Won),심윤수(Shim, Yoon Soo),서충원(Suh, Chung Won) 한국부동산학회 2014 不動産學報 Vol.58 No.-

국가 및 지방공기업에서 향후 토지리턴제 운용 시 개선해야 할 사항들을 정리하면 다음과 같다. 첫째, 금융투기 수요 참여 사전방지를 위해 리턴금리의 적정한 기준설정이 필요하다. 둘째, 리턴권 행사기간은 계약체결일로부터 장기로 설정하는 것을 지양해야 한다. 셋째, 완납납입형 토지리턴제는 지양해야 한다. 넷째, 토지리턴제 적정 기준에 대한 법적 수단이 함께 강구될 필요가 있다. 무조건적인 법적 규제를 통한 토지리턴제의 운용 불허보다는 적정한 기준을 구체적으로 설정하여 운용의 자율권을 부여하는 것이 필요하다. 1. CONTENTS (1) RESEARCH OBJECTIVES The purpose of this study was to investigate the concept and the types of Land Return System, explore its current status and major issues focusing on the cases of Land Return System operated by each public enterprise and suggest a future direction for the improvement of Land Return System. (2) RESEARCH METHOD As a method for this study, case analysis method was used. The data for the analysis was based on the provision notices for Land Return System. (3) RESEARCH FINDINGS The major issues of Land Return System summarized through the case analysis were as follows. 1) The criteria to determine return interest and the practice of loan-based deal. 2) Since a public enterprise guarantees to buyer the return interest until its maturity date, there is possibility that speculative capitals may participate in the bids and take a benefit out of it. 3) Revenue recognition is not made on land until buyer executes or waive the return right, buyer may lose the opportunities to sell to end users depending on the established period of executing the return right. 4) The Ministry of Security and Public Administration made a pre-announcement of legislation for the partial amendment of the Local Public Enterprises Act. If this amendment is passed, local public enterprises cannot sell their assets with the condition of Land Return System. 2. RESULTS Following points should be improved in the operation of Land Return System. 1) It is necessary to set up an appropriate criteria of return interest in order to prevent the participation of speculative capitals. 2) The period of exercising return right should not be setup with long term period from the date of contract. 3) Full-payment type Land Return System should be avoided. There is also a necessity to seek for legal means to regulate the appropriate criteria for Land Return System.

Selective disassembly sequencing with abnormal operations and random operation times

김형원(Hyung-Won Kim),도형호(Hyoung-Ho Doh),이동호(Dong-Ho Lee) 대한산업공학회 2018 대한산업공학회 춘계학술대회논문집 Vol.2018 No.4

Selective disassembly sequencing with abnormal operations and random operation times

김형원(Hyung-Won Kim),도형호(Hyoung-Ho Doh),이동호(Dong-Ho Lee) 한국경영과학회 2018 한국경영과학회 학술대회논문집 Vol.2018 No.04

FPGA를 이용한 10Gbps의 속도를 갖는 패킷 분류 엔진 구현 및 검증

김형원(Hyung-Won Kim),채원식(Won-Sik Chae) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.6

Heuristic Algorithms for the Mixed-model Disassembly Line Balancing Problem

Hyung-Won Kim(김형원),Kwang-Bok Lee(이광복),Dong-Ho Lee(이동호) 한국SCM학회 2008 한국SCM학회지 Vol.8 No.2

축소 모사형 고체 추진기관 설계에 관한 연구

김형원(Hyung-Won Kim),오종윤(Jong_Yun Oh) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5

A design of a subscale solid propellant rocket motor was conducted to do the similitude experiments for the large scale rocket motor. One of the main factor to subscale was the mach number of the solid propellant flume through a nozzle exit The analysis of the flume flow was done to obtain the mach number for the large and subscale rocket motor. The flume shapes on the non dimensional axises by the nozzle exit diameter was matched each other. The propellant grain of a subscale solid rocket motor was designed by the profile of pressure vs time obtained by the mach number of the flume shape. Some analyses of the theoretical solution were compared with the results of the ground static test.

총설 : 화장품용 천연계면활성제의 제조 및 이용 최신기술

김형원 ( Hyung Won Kim ) 한국 접착 및 계면학회 2013 접착 및 계면 Vol.14 No.4

계면활성제는 상간의 경계면 활성화를 통한 표면장력의 강하능력을 가져 모든 세제(detergents) 와 화장품(cosmetics)에 사용되는 필수 주원료이다. 합성세제란 석유화학계의 EO (ethylene oxide), LAB (linear alkylbenzene) 등의 합성계면활성제로 제조한 제품으로 이는 난분해성으로 지구환경, 특히 하천과 강물오염의 주범으로 생태계파괴의 원인이 되고 있다. 이는 또한 분자가 작아 침투력이 강해피부를 자극하여 아토피피부염을 유발하고 모세관을 통해 기관으로 들어가면 암을 유발할 수도 있다. 최근 합성계면활성제를 대체할 수 있는 양친매성의 생분해성 친환경 및 무자극의 다기능성물질로서 천연 계면활성제 또는 생합성의 생물 계면활성제(biosurfactants)의 개발에 국제적인 관심이 고조되고 있다. Surfactants which have ability to decrease surface tension through surface activation between the interfaces are used as essential major raw materials for detergents and cosmetics. Typical synthetic detergents such as EO (ethylene oxide), LAB (linear alkylbenzene) are made from chemical surfactant derived from petrochemicals, therefore, they are responsible for major environment contaminations and ecosystem destruction, especially of rivers and also cause atopic dermatitis through strong skin stimulus of these small molecular`s powerful permeability and lead to cancers if they get into organs through capillary. Now worldwide interest is increasing to develop new natural surfactants and biosurfactants as ecological, biodegradabl, harmless and multi-functional new amphiphillic materials which replace these synthetic surfactants.

고체 추진기관 선진국 기술 동향에 관한 연구

김형원(Hyung-Won Kim),박종승(Chong-Seung Park) 한국추진공학회 2010 한국추진공학회 학술대회논문집 Vol.2010 No.11

최근에 인공위성을 궤도에 올리는데 막대한 비용이 들어가므로, 소형이면서 좀 더 신뢰도가 높은 인공위성이 요구되어 왔다. 추진제의 새로운 바인더(HTPB, GAP)와 산화재(CL20, ADN)의 발명은 로켓의 추력을 다양하게 하는데 많은 기여를 했다. 제조 공정을 획기적으로 변화시키는 낮은 온도에서 녹는 열가소성 추진제는 비용을 상당히 절감시켰다. 인공위성을 궤도에 정확하게 안착시키는데 어려움이 있었던 고체 연료 로켓은 액체추진제를 사용하는 PBS를 상단에 추가 설치함으로 정확도를 증진시켰다. 이 논문에서 또한 선진화된 노즐재료와 연소관에 대해서도 방향을 제시한다. Recently, due to the enormous cost for sending a satellite into an orbit, small and more reliable satellites have been more demanded. An introduction of new binders(HTPB, GAP) and new oxidizers made great improvements of the large thrust modulation. In order to make cost reduction, one prefers to the low melting temperature thermoplastic propellant reforming the manufacturing process dramatically. Solid propellant rockets have been had a problem of the injection accuracy into orbit, but PBS(Post Boost Stage) using a liquid mono-propellant improves the injection accuracy. This paper also gives the direction of the advanced nozzle materials and the motor case.