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지하철 구조물의 성능저하 현황 및 내구성 향상을 위한 보수공법
유재강 ( Yoo¸ Jae-kang ),이강우 ( Lee¸ Kang-woo ),강석표 ( Kang¸ Suk-pyo ),권영진 ( Kwon¸ Young-jin ),김무한 ( Kim¸ Moo-han ) 한국구조물진단유지관리공학회 2000 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.4 No.2
In the city life, the subway is the main core-traffic network. Because many people use the subway, the subway structure required high security and long-term durability. As time elapsed, the concrete structure become deteriorated by the many of deterioration factors and the environmental conditions. So, it is important that the diagnosis and the repair on time for increasing durability. This paper shows the deteriorated condition of Seoul subway structures, and present the repair method which was suggested by the Architectural Institute of Japan.
THE IMPACT OF THE NUMBER OF CROWDFUNDING ROUND ON CONSUMER RESPONSES AND THE FUNDING SUCCESS
Jaekang Heo,Inyoung Chae,Ahyoung Kim 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07
The purpose of this research is to examine the impact of firms’ repeated use of crowdfunding on consumer responses and the funding success, focusing on compensatory crowdfunding that provides products and services when funding is successful. The result indicates that the number of crowdfunding round and achievement rates are related to parabolic forms. These results suggest that investors can recognize the number of crowdfunding round as a important signal for crowdfunding investment. In addition, this research aims to present practical implications for crowdfunding firms and platforms to attract ongoing investments.
시프트 연산과 난수를 이용한 가변적 대칭키 기반의 RFID 상호인증 프로토콜
이재강(Jaekang Lee),오세진(Sejin Oh),정경호(Kyungho Chung),이창희(Changhee Lee),안광선(Kwangseon Ahn) 한국통신학회 2012 韓國通信學會論文誌 Vol.37 No.5B
RFID 시스템은 무선 주파수를 이용하여 태그의 정보를 얻는 기술이다. 그러나 무선 주파수를 이용하는 특성으로 도청, 위치추적, 스푸핑 공격, 재전송 공격, 서비스 거부 공격에 취약하다. 그래서 RFID 프로토콜이 안전하고 프라이버시를 위해 암호학적 기법과 상호인증 기법이 사용되어 진다. 본 논문에서는 기존의 프로토콜의 문제점을 알아보고, 다양한 공격에 안전한 프로토콜을 제안한다. 뿐만 아니라 시프트 연산과 난수를 이용한 가변적 대칭키 생성으로 비밀키에 대한 문제점을 해결한다. RFID system is a technique to obtain information of tag using radio frequency. Specificity of RFID systems using radio frequency has many problems that is eavesdropping, location tracking, spoofing attack, replay attack, denial of service attack. So, RFID protocol should be used cryptographic methods and mutual authentication for security and privacy. In this paper, we explain the problem of past protocol and propose the nonfixed symmetric key-based RFID mutual authentication protocol using shift computation and random number. Proposed protocol is secure from various attacks. Because it use shift operation and non-fixed symmetric key.
송재강(Jaekang Song),박주현(Joohyen Park),문종훈(Jonghoon Moon),이장환(Janghwan Lee),김용욱(Yongwook Kim),김형근(Hyeungkeun Kim) 한국추진공학회 2019 한국추진공학회 학술대회논문집 Vol.2019 No.5
한국형발사체 추진제탱크의 가압방식으로는 극저온 저장가스 가압시스템이 적용되어졌다. 극저온 유체로는 헬륨이 사용되어졌으며, 발사체 내에서 극저온 상태 유지를 위하여 산화제(액화산소) 저장탱크내 극저온 헬륨 저장탱크를 위치하도록 하였다. 산화제 탱크 내 위치한 헬륨 탱크에 상온 헬륨을 공급할 경우, 헬륨과 산화제의 급격한 온도차로 인하여 여러 문제점을 발생시킬 수 있다. 따라서 가압용 헬륨 충전을 위해서는 산화제와의 온도차를 줄이기 위한 지상 공급시스템의 냉각 장치가 필요하다. 또한 헬륨 냉각용 열교환기는 설치 후 비용, 인허가 및 반출입의 제약으로 인해 보완이 어렵다. 따라서 본 연구에서는 대수평균 온도차 기법과 Pilot test를 통한 액화질소를 냉매로 사용한 헬륨 냉각용 열교환기의 설계 방법에 대하여 알아보고자 하였다. A cryogenic storage gas pressurization system was applied as a pressurization method for the propellant tank of KSLV-Ⅱ. Helium was used as the cryogenic fluid and the cryogenic helium storage tank in the oxidizer(LOx) storage tank was positioned to continue cryogenic conditions in the projectile. When room temperature helium is supplied to a helium tank located in an oxidizer tank, various problems may be caused due to a rapid temperature difference between helium and oxidizer. Therefore, for the pressurized helium charging, a cooling system of the ground supply system is required to reduce the temperature difference with the oxidizer. Also after installing, the heat exchanger for helium cooling is difficult to improve due to costs, permission for high pressure gases and import / export restrictions. Therefore, in this study, the design method of helium cooling heat exchanger using liquefied nitrogen as a refrigerant through logarithmic mean temperature difference method and pilot test was investigated.
추진기관시스템 시험설비 고압가스 배관 청결화 및 압력시험 절차 소개
송재강(Jaekang Song),우희찬(Heechan Woo),이장환(Janghwan Lee) 한국추진공학회 2019 한국추진공학회 학술대회논문집 Vol.2019 No.11
발사체 개발 과정 중 하나인 단 인증시험을 위한 추진기관시스템 시험설비(PSTC)에 사용되는 고압가스 공급을 위한 배관은 규격 만족 및 안전을 위해 청결도가 만족되어야 한다. 본 논문에서는 추진기관시스템 시험설비(PSTC) 구축을 통해 경험한 배관의 청결화 방법과 안전성 입증을 위한 압력시험 절차에 대하여 소개하고자 한다. 배관의 청결화 및 압력시험에 사용된 유체는 배관의 오염을 방지하기 위해 불활성 기체인 질소를 적용하였다. 배관의 청결화를 위한 방법으로는 블로윙을 적용하였으며, 에너지 보존의 법칙을 이용한 등운동에너지를 만족하는 조건에서 진행하였다. 배관의 안전성 검증을 위한 압력시험은 고압가스안전관리법에 의거하여 진행하였으며, 시험으로 인한 안전사고를 방지하기 위해 배관 저장에너지에 따른 TNT 환산량 및 안전거리 검토를 수행하여 반영하였다. Pipeline for supplying high pressure gas used in Propulsion System Test Complex(PSTC) for certification test of the projectile stage, one of the projectile development process, should be cleaned for satisfactory of specification and safety. In this paper, We introduce the pipe cleaning method and the pneumatic pressure test procedure to prove the safety that we experienced through the construction of the Propulsion System Test Complex(PSTC). The fluid used for pipe cleaning and pressure test was nitrogen as an inert gas to prevent contamination of the pipe. Blowing was applied as a method for cleanliness of the pipe, and it proceeded under conditions satisfying the iso-momentum using the law of energy conservation. The pneumatic pressure test to verify the safety of the pipe was conducted in accordance with the High Pressure Gas Safety Management Act. And in order to prevent safety accidents caused by the test, conversion amount of TNT and the safety distance according to the pipe storage energy were reviewed and reflected.
정재강(JaeKang Chung),김재열(JaeYeol Kim),김우진(Woojin Kim) 한국트라이볼로지학회 2006 한국윤활학회지(윤활학회지) Vol.22 No.4
The issue with the drainpipe now a day is that they are laid underground. Causing us to perform additional work to repair, such as digging up the ground and peeling off the insulator that surrounds the pipe. And such series works are difficult that concession appears from government and municipal office. However, if we can save time and money. Performance of piping robot that we are studied in existing session through fixing unit and improvement of cutting bit shorten and wished to heighten work efficiency. And we are trying to develop a unit that can cut up the projecting parts which connects with the interior part of the drainpipes.