양방향 평균화를 이용한 새로운 Mid-amble 기반V2X 채널추정 기법에 관한 연구

김주혁,송창익 한국전기전자학회 2022 전기전자학회논문지 Vol.26 No.2

In general, as the amplitude and phase information of the physical layer channel impulse response change rapidly in time and frequency according to the high-speed movement of the vehicles in V2X communication systems, it is difficult to accurately estimate these channels at the receiving end. In order to effectively overcome this problem, midamble-based channel estimation methods in which mid-ambles are periodically inserted into a packet have been recently considered. However, as the number of midambles increases, we suffer from the spectral efficiency loss. To relieve such a loss, in this paper, we propose a new bidirectional averaging channel estimation method that combines the existing data pilot-based channel estimation methods and the mid-ambles. Finally, through the simulation results, we demonstrate that the proposed method outperforms the existing mid-amble method in terms of packet error rate with fewer number of mid-ambles. 일반적으로 V2X 통신은 차량의 고속이동에 따라 물리계층 채널 임펄스 응답의 진폭과 위상정보가 시간 및 주파수에서 빠르게 변 화하기 때문에, 수신단에서 이러한 채널을 정확하게 추정히는- 것이 매우 어려운 일이다. 이러한 문제를 효과적으로 극복하기 위해 최근 패킷 내부에 주기적으로 미드앰블을 삽입하는 미드앰블 기반 채널추정 방식이 고려되고 있다. 하지만 단순히 미드엠블올 삽입 하는 방법은 미드앰블의 수가 증가할수록 성능 이득 대비 주파수 효율이 빠르게 감소하는 문제점을 가지고 있다. 본 논문에서는 이 러한 문제점을 해결하기 위해 기존의 데이터 파일럿 기반 채널추정방법과 미드앰블 방법을 결합한 새로운 양방향 평균화 채널추정 기법을 제안한댜 제안하는 기법은 이러한 평균화 과정과 미드앰블의 위치 최적화를 통해 보다 적은 수의 미드앰블로 채널 추정의 정확도를 비약적으로 향상시킬 수 였다. 마지막으로 미드앰블의 수에 따른 패킷오류율 시뮬레이션을 통해 주파수 효율 관점에서 제 안하는 기법의 우수성을 입증한댜

한라산 가족

김주혁 고요아침 2019 한국동시조 Vol.- No.14

해외 사장 개척은 '신뢰감' 구축으로 시작

김주혁,Kim, Ju-Hyeok 한국정보통신집흥협회 2006 정보화사회 Vol.179 No.-

소프트웨어 분야는 2~3년을 손해 보더라도 신뢰감을 쌓는 것이 무엇보다 중요하다. 원하는 비즈니스를 지속적으로 보여줘야지 고위층 인사와의 친분 등 '과시'만으로 비즈니스가 되는 건 아니다.

이산화탄소/프로판 혼합냉매의 냉방성능 특성

김주혁,김민수 대한설비공학회 2006 설비공학 논문집 Vol.18 No.1

CO2 and propane mixtures were chosen as promising alternative refrigerants and their performance potentials were evaluated experimentally in an air-conditioning system. Pure CO2 and 85/15, 75/25 and 60/40 binary blends by the charged mass percentage of CO2/ propane were selected as working fluids. The effect of the inlet temperature of the secondary fluids and degree of superheat on the cooling performance was tested and discussed. The charging amounts of refrigerants were adjusted to make the system show the maximum COP. Comparisons among different refrigerants were carried out on the same compressor speed basis for a given operating condition. In addition, the temperature gliding effect of zeotropic mixtures on the system performance were analyzed based on the drop-in test results.

이산화탄소/프로판 혼합냉매의 냉방성능에 대한충전량의 영향 및 순환성분비 변화 특성

김주혁,황윤욱,김민수 대한설비공학회 2006 설비공학 논문집 Vol.18 No.11

CO2 and propane mixtures, which are environmentally benign, nontoxic, low in price, and compatible with materials and lubricants, were considered as promising alternative refrigerants. A fully instrumented air-conditioning system was developed for a precise performance evaluation of pure CO2 and CO2/propane mixtures. In this paper, the effect of the charging amount and circulation concentration on the cooling performance of the system using CO2 and propane mixtures was tested and discussed. Pure CO2 and 85/15, 75/25 and 60/40 binary blends by the charged mass percentage of CO2/propane were selected as working fluids. An optimum charging amount was proposed as a parameter instead of the degree of subcooling, which can not be well defined in the transcritical cycle, to properly compare the performance between the transcritical and subcritical cycles.

바이너리 수준에서의 Jump-Oriented Programming에 대한 탐지 메커니즘

김주혁,이요람,오수현 한국정보보호학회 2012 정보보호학회논문지 Vol.22 No.5

It is known that memory has been frequently a target threatening the computer system's security while attacks on the system utilizing the memory's weakness are actually increasing. Accordingly, various memory protection mechanisms have been studied on OS while new attack techniques bypassing the protection systems have been developed. Especially, buffer overflow attacks have been developed as attacks of Return to Library or Return-Oriented Programing and recently, a technique bypassing the countermeasure against Return-Oriented Programming proposed. Therefore, this paper is intended to suggest a detection mechanism at binary level by analyzing the procedure and features of Jump-Oriented Programming. In addition, we have implemented the proposed detection mechanism and experimented it may efficiently detect Jump-Oriented Programming attack. 컴퓨터 시스템의 안전성을 위협하는 주요 취약점으로 메모리 관련 취약점이 알려져 있으며, 최근 들어 이러한 메모리 취약점을 이용한 시스템 상에서의 실제 공격 또한 증가하고 있다. 이에 따라 시스템을 보호하기 위해서 다양한 메모리 보호 메커니즘들이 연구되고 운영체제를 통해 구현되어 왔지만, 더불어 이를 우회할 수 있는 공격 기법들 또한발전하고 있다. 특히 버퍼 오버플로우 공격은 Return to Library, Return-Oriented Programming 등의 공격기법으로 발전되어왔으며, 최근에는 Return-Oriented Programming 공격 기법에 대한 보호 방법 등의 연구로인해 이를 우회하는 Jump-Oriented Programming 공격 기법이 등장하였다. 따라서 본 논문에서는 메모리 관련공격 기법 중 최근 등장한 Jump-Oriented Programming 공격 기법에 대해 살펴보고, 이에 대한 특징을 분석한다. 또한, 분석된 특징을 통한 바이너리 수준에서의 탐지 메커니즘을 제안하고, 실험을 통해 제안하는 방법이Jump-Oriented Programming 공격에 대한 탐지가 가능함을 검증한다.

The Development of SiC Supported Iron Oxide Sorbent for H₂S Removal

김주혁,김희택 한국공업화학회 2002 한국공업화학회 연구논문 초록집 Vol.2002 No.0

Iron oxide sorbent supported on SiC which was sintered for porous structure have been prepared and characterized by SEM and XRD. Antimony trioxide was added as additive for direct sulfur recovery. This sorbent showed good performance for H₂S removal and also exhibited high stability in the sulfidation and regeneration cycle. The characteristics of sorbent reactivity were investigated using TGA and reaction temperature changed from 450 to 650°C. The optimum value of reaction temperature was 600°C and the result of sulfur loading was 18 wt%.

더덕 속 식물의 구분을 위한 InDel 마커의 개발

김주혁,정영훈,이미선,김문교,조남수,구성철,이이,길진수 한국약용작물학회 2023 한국약용작물학회지 Vol.31 No.1

Background: Three medicinal plants of the Campanulaceae, Codonopsis lanceolata, C. pilosula, and C. ussuriensis are perennial vines of the genus Codonopsis, and are widely disturbuted in East Asia. C. lanceolata, C. pilosula, and C. ussuriensis have been used as medicine to alleviate inflammation, increase red blood cell count and hemoglobin levels, and improve spleen and stomach functions, respectively. The three species have similar morphologies, although their pharmacological effects differ. Methods and Results: We identified polymorphic loci by comparing chloroplast and mitochondrial sequences of C. lanceolata, C. pilosula, and C. ussuriensis. We designed primers based on these polymorphic loci and conducted polymerase chain reaction (PCR) analysis to verify the polymorphisms. Three insertion–deletion (InDel) markers were ultimately developed: CD-mt-02, which identified C. pilosula; CD-mt-06, which identified C. ussuriensis; and CD-cp-07, which identified all the three species. Conclusions: The three InDel markers developed in this study easily distinguished the three plant species based on a simple PCR test.

SiC 를 지지체로한 산화철 흡착제 제조

김주혁,김희택 한국공업화학회 2002 한국공업화학회 연구논문 초록집 Vol.2002 No.1

이산화탄소와 프로판 혼합냉매의 기상-액상 평형

김주혁,김민수,김만회 대한설비공학회 2006 설비공학 논문집 Vol.18 No.11

This paper presents the vapor-liquid equilibrium(VLE) data measured for carbon dioxide and propane mixtures. Their mixtures were considered as promising alternative refrigerants due to good thermophysical properties and negligible environmental impact. The isothermal VLE data were measured at eight temperatures ranging from 253.15 to 323.15K in the circulation type equipment with a view cell. The binary system was found to be a zeotropic mixture in the tested temperature range and could be correlated with sufficient accuracy by using the Peng-Robinson equation of state(PR EoS) with the van der Waals one fluid mixing rule. A comparison with published experimental VLE data has been carried out by means of the PR equation of state. In addition, the phase behaviors of carbon dioxide and propane mixtures were analyzed based on the measured VLE data.