시론 : 북한이 동시에 제시한 2개의 카드 합영법과 수재물자

윤동현 평화문제연구소 1984 통일한국 Vol.13 No.-

<SUP>13</SUP>C₂H₂ 분자 전이선의 파장 측정

윤동현,유준 한국통신학회 2002 한국통신학회 기타 간행물 Vol.2002 No.10

코히어런트 간섭문제 해결을 위한 공간보간 Duvall 빔형성기

윤동현,한동석,고광식,조명제,Yun, Dong-Hyeon,Han, Dong-Seok,Go, Gwang-Sik,Jo, Myeong-Je 대한전자공학회 2002 電子工學會論文誌-SP (Signal processing) Vol.39 No.1

본 논문은 공간보간을 이용한 공간평활을 수행하는 수정된 구조의 Duvall 빔형성기를 제안한다. 제안한 빔형성기는 이웃한 어레이 소자 사이의 신호를 보간하여 가상의 어레이 소자 신호를 생성하고 이를 이용하여 공간평활을 수행한다. 제안한 빔형성기는 보간된 신호를 이용하여 부어레이를 형성함으로써 기존 공간평활 기법의 자유도 손실 문제를 해결한다. 수학적 분석을 통하여 제안한 빔형성기는 입력 공분산 행렬의 감소된 랭크를 회복할 수 있음을 확인하였다. 또한 모의실헐 결과에서도 제안한 빔형성기는 기존의 빔형성기가 제거할 수 없는 코히어런트 간섭신호를 제거함을 보였다. This paper proposes a modified Duvall beamformer performing spatial smoothing with spatial interpolation. In the proposed beamformer, virtual array signals are generated by spatial interpolation between each neighbor array elements, then all signals are used to perform spatial smoothing. The proposed beamformer overcomes the loss of degrees of freedom caused by spatial smoothing by forming subarrays with interpolated signals. Mathematical description shows that the proposed beamformer can restore the rank of away covariance matrix. Accordingly, the proposed beamformer can minimize the loss of degrees of freedom. Simulation results show that the proposed beamformer can remove all coherent interferences while conventional beamformers cannot.

항공기 터빈 디스크용 니켈기 초내열 분말야금 합금의 고온 피로균열진전 거동 비교 평가

윤동현,나성현,김재훈,김홍규,김동훈,Yoon, Dong Hyun,Na, Seong Hyeon,Kim, Jae Hoon,Kim, Hongkyu,Kim, Donghoon 대한기계학회 2017 大韓機械學會論文集A Vol.24 No.2

항공기 터빈 디스크에 사용될 수 있는 니켈기 초내열 분말야금 합금의 피로균열진전 거동이 실제운전 환경을 고려하여 상온 및 $650^{\circ}C$에서 연구되었다. ASTM E647에서 제시하는 직류전위차법을 이용하여 실시간으로 균열의 진전을 측정하였다. 또한 피로균열진전 시험은 응력비 0.1과 0.5의 두가지 조건에서 수행되었다. 시험결과들은 응력비와 온도 조건 모두 피로균열진전 거동에 영향이 있음을 보여주었으며, 응력비와 온도가 증가함에 따라, 니켈기 초내열 분말 야금 합금의 피로균열성장 속도는 증가하게 관찰되었다. 본 연구에서 사용된 니켈기 초내열 분말 야금 합금은 현재 개발 중인 소재로써 보다 정량적인 시험결과의 분석을 위해, 본 연구의 피로균열진전 시험결과와 기존에 연구된 Inconel-100 소재의 피로균열진전거동에 대한 상호 비교분석이 수행되었다. 피로균열진전 파단면의 분석은 SEM 촬영을 통하여 수행하였다. The behavior of fatigue crack growth of nickel-based powder metallurgy superalloy that could be used in aircraft turbine disc is investigated at room temperature, and $650^{\circ}C$ considering real operating conditions. The direct current potential drop(DCPD) method was used to measure the crack length of material in real time according to ASTM E647. Tests were performed with various stress ratios (0.1 and 0.5). Experimental results show that stress ratio, and temperature all affect the behavior of fatigue crack growth. As the stress ratio and temperature increase, the fatigue crack growth rate of nickel-based powder metallurgy superalloy also increases. Results were compared and reviewed with fatigue crack growth rates of other nickel-based superalloy materials (Inconel-100) that were studied in previous papers. Fractography analysis of the fractured specimens was performed using as SEM.

Fracture behavior of C/SiC composites at elevated temperature

윤동현,이정원,김재훈,신인철,임병주 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

The fracture behavior of carbon fiber-reinforced silicon carbide (C/SiC) composites used in rocket nozzles has been investigated under tension, compression, and fracture conditions at room temperature, 773 K and 1173 K. The C/SiC composites used in this study were manufactured by liquid silicon infiltration process at ~1723 K. All experiments were conducted using two types of specimens, considering fiber direction and oxidation condition. Experimental results show that temperature, fiber direction, and oxidation condition affect the behavior of C/SiC composites. Oxidation was found to be the main factor that changes the strength of C/SiC composites. By applying an anti-oxidation coating, the tensile and compressive strengths of the C/SiC composites increased with temperature. The fracture toughness of the C/SiC composites also increased with increase temperature. A fractography analysis of the fractured specimens was conducted using a scanning electron microscope.

스마트팩토리 교육을 위한 PLC를 이용한 MES에서 C# 프로그램 구현

윤동현 한국산업기술융합학회 2022 산업기술연구논문지 (JITR) Vol.27 No.2

In this study, C# codes were implemented in a manufacturing execution system using a programmable logic controller for education of a smart factory. In the existing environment of an aviation campus, when MES education for a smart factory was conducted, HMI or SCADA programs were used as PLC-only software, and the trainees were limited to PLC specialized skills; therefore, MES specialists were nurtured. However, when implementing an OPC server and MS-SQL in PLC equipment by strengthening a smart factory system environment, notably, the control/monitoring function of an MES could be implemented using C# programs without using HMI or SCADA programs as PLC dedicated SW. It is expected that it will be of great help in finding employment by nurturing the MES manpower required in the industrial field, not limited to PLC specialized skills, as it provides trainees with a basic and functional understanding of the MES and C# program education. .

통합교육을 위한 초등학교 특수학급영역 설계방향에 관한 연구 - 특수학급 아동의 장소성을 중심으로 -

윤동현,이선영,Yoon, Dong-Hyun,Rieh, Sun-Young 한국교육시설학회 2014 敎育施設 Vol.21 No.2

Elementary School is a special facility where sense of place plays critical role for the development of children. Children in special education call for special attention as they hold inferior status compared to the children in regular class especially under the inclusive education policy. Eight cases of special education class area are analyzed in terms of social space, personal space and favorite place which is known to be basic factor for the development. As a result outdoor space found to be designed inappropriate even when designed accessible to the special education class as it could not meet the developmental needs of children in special education. Special education class area inside the building is also found to be too exclusive to allow social mix with children in regular class disregarding the intention of inclusive education. Location of these class should be strategic as it is critical to be linked with regular classroom efficiently still allowing psychological buffer as the children in special education tend to form restorative space inside the special education classroom showing the possibility of creating sense of place there.

Hold time-Low Cycle Fatigue Behavior for Nickel Based Hastelloy X at Elevated Temperatures

윤동현,허인강,김재훈,장성영,장성호 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.1

Hastelloy X, a material used in gas turbines, is subject to complex damage because of creep and fatigue in a high temperature environment during the operation of gas turbines. Although the low cycle behavior of Hastelloy X has been widely investigated, the number of studies focusing on the actual operating conditions of the gas turbine is limited. In this study, the total strain range of the gas turbine at 760 °C and 870 °C was considered as a parameter of the actual gas turbine operation. In addition, tests were performed with a trapezoidal waveform of the total strain to reflect the operation—stop status of the gas turbine with frequent shutdown times. The results of the fatigue test were studied with the Coffin-Manson method and the lifetime prediction equation was derived based on the data. Fractography was performed using scanning electron microscopy (SEM) observation.

셀룰러 오토마타를 이용한 산사태 재난지역 분석에 관한 연구 - 서울특별시 서초구 우면산을 대상으로-

윤동현,고준환 대한공간정보학회 2012 Spatial Information Research Vol.20 No.1

South Korea has many landslides caused by heavy rains during summer time recently and the landslides continue to cause damages in many places. These landslides occur repeatedly each year, and the frequency of landslides is expected to increase in the coming future due to dramatic global climate change. In Korea, 81.5% of the population is living in urban areas and about 1,055 million people are living in Seoul. In 2011, the landslide that occurred in Seocho-dong killed 18 people and about 9% of Seoul's area is under the same land conditions as Seocho-dong. Even the size of landslide occurred in a city is small, but it is more likely to cause a big disaster because of a greater population density in the city. So far, the effort has been made to identify landslide vulnerability and causes, but now, the new demand arises for the prediction study about the areal extent of disaster area in case of landslides. In this study, the diffusion model of the landslide disaster area was established based on Cellular Automata(CA) to analyze the physical diffusion forms of landslide. This study compared the accuracy with the Seocho-dong landslide case, which occurred in July 2011, applying the SCIDDICA model and the CAESAR model. The SCIDDICA model involves the following variables, such as the movement rules and the topographical obstacles, and the CAESAR model is also applied to this process to simulate the changes of deposition and erosion. 최근 우리나라는 여름에 집중호우로 인한 산사태로 그 피해가 계속되고 있다. 이러한 산사태는 매년 반복적으로 발생하고 있으며 급격한 기후의 변화로 인해 앞으로 그 발생빈도가 높아질 것으로 예측된다. 우리나라는 인구의 81.5%가 도시지역에 거주하고 있으며 서울에만 약 1,055만 명이 거주하고 있다. 2011년 18명의 사망자가 발생한 서초동 산사태와 동일한 조건에 인접한 대지는 서울시에서 약 9%에 달한다. 도시에서 발생하는 산사태는 그 규모는 작으나 인구가 집중하는 도시의 특성으로 인해 큰 재난을 야기할 가능성이 있다. 현재까지는 산사태의 취약성과 발생 원인을 규명하기 위한 노력이 지속되어 왔으나 산사태 발생 시 재난지역의 범위에 관한 예측 연구가 새롭게 요구되고 있다. 이에 본 연구에서는 산사태의 물리적 확산형태를 분석하기 위하여 셀룰러 오토마타(Cellular Automata, CA) 기반의 산사태 재난지역 확산모델을 구축하였다. 이동규칙, 지형에 의한 장애물을 변수로 하는 SCIDDICA(Smart Computational Innovative methoDs for Debris flow simulation with Cellular Automata)모델과 침전 및 침식에 따른 변화를 적용한 CAESAR(the Cellular Automaton Evolutionary Slope And River model)모델을 적용하여 2011년 7월 서초동 산사태를 대상으로 정확도를 비교하였다.

최근 60년간 도시 및 농촌 지역의 국지적 기후변화 비교 분석

윤동현,남원호,홍은미,김태곤,허창회,Yoon, Dong-Hyun,Nam, Won-Ho,Hong, Eun-Mi,Kim, Taegon,Ho, Chang-Hoi,Hayes, Michael J. 한국농공학회 2018 한국농공학회논문집 Vol.60 No.3

Local climate characteristics for both urban and rural areas can be attributed to multiple factors. Two factors affecting these characteristics include: 1) greenhouse gases related to global warming, and 2) urban heat island (UHI) effects caused by changes in surface land use and energy balances related to rapid urbanization. Because of the unique hydrological and climatological characteristics of cities compared with rural and forested areas, distinguishing the impacts of global warming urbanization is important. In this study, we analyzed anthropogenic climatic changes caused by rapid urbanization. Weather elements (maximum temperature, minimum temperature, and precipitation) over the last 60 years (1955-2016) are compared in urban areas (Seoul, Incheon, Pohang, Daegu, Jeonju, Ulsan, Gwangju, Busan) and rural/forested areas (Gangneung, Chupungnyeong, Mokpo, and Yeosu). Temperature differences between these areas reveal the effects of urbanization and global warming. The findings of this study can be used to analyze and forecast the impacts of climate change and urbanization in other urban and non-urban areas.