지역난방 첨두부하보일러 대류부 부식 파손 분석

김영수 ( Youngsu Kim ),채호병 ( Hobyung Chae ),홍민기 ( Minki Hong ),송민지 ( Min Ji Song ),조정민 ( Jeongmin Cho ),김우철 ( Woo Cheol Kim ),하태백 ( Tae Baek Ha ),이수열 ( Soo Yeol Lee ) 한국부식방식학회(구 한국부식학회) 2019 Corrosion Science and Technology Vol.18 No.2

Corrosion failure in the convection part of peak load boiler (PLB) of the district heating system led to water leakage. Herein, Internal Rotary Inspection System (IRIS) inspection was employed to examine wall thinning and the cause of leakage in the flue tube. The corrosive products of the turbulator and tube were investigated using scanning electron microscope combined with energy dispersive spectroscopy, X-ray diffraction, and inductively coupled plasma (ICP). Majority of the serious corrosion damage was observed near the turbulator located in the upper flue tube. ICP analysis of the boiler water revealed oxide formation of sodium chloride in the lower end part of the flue tube. A cross-sectional view of the turbulator revealed the presence of double-layers of the oxide film, indicating environmental change during operation associated with water leakage. The outer surface of the turbulator consisted of the acid oxides such as NO_x and SO_x along with sodium and chloride ions. Dew-point corrosion is hypothesized as the main cause for the formation of acid oxides in the region of contact of the flue tube and the turbulator.

Levenberg-Marquardt 알고리즘의 지반공학 적용성 평가

김영수(Kim Youngsu),김대만(Kim Daeman) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.5

본 연구에서는 Levenberg-Marquardt(LM) 알고리즘 인공신경망을 통하여 지반공학 문제 중의 하나인 압축지수를 예측하였고, 예측된 결과는 현재 지반공학에 널리 사용되고 있는 Back Propagation(BP) 알고리즘 인공신경망의 예측 결과와 비교하여 LM알고리즘의 지반공학 적용성을 평가하였다. 또한 두 알고리즘에 의한 예측치는 기존에 제안된 압축지수의 경험식들에 의하여 산정된 결과들과 비교를 통하여 예측결과의 정확성을 확인하였다. 경험식에 의한 압축지수의 산정치는 전반적으로 BP 알고리즘과 LM 알고리즘 인공신경망에 의한 예측치에 비하여 더 큰 오차를 나타냈다. LM 알고리즘에 의한 압축지수의 예측치는 BP 알고리즘의 예측치와 비교할 때 정확도는 비슷하나 수렴속도에서 더 좋은 결과를 보여 LM 알고리즘의 지반공학 적용성은 우수한 것으로 나타났다. In this study, one of the complicated geotechnical problem, compression index was predicted by a artificial neural network method of Levenberg-Marquardt (LM) algorithm. Predicted values were compared and evaluated by the results of the Back Propagation (BP) method, which is used extensively in geotechnical engineering. Also two different results were compared with experimental values estimated by verified experimental methods in order to evaluate the accuracy of each method. The results from experimental method generally showed higher error than the results of both artificial neural network method. The predicted compression index by LM algorithm showed better comprehensive results than BP algorithm in terms of convergence, but accuracy was similar each other.

터널의 필러부 폭에 따른 터널거동

김영수(Kim Youngsu),권태순(Kwon Taesoon),정일한(Jeong Ilhan),김광일(Kim Kwangil) 한국지반환경공학회 2009 한국지반환경공학회논문집 Vol.10 No.7

대상 연구지역은 화강암 지역으로서 단층파쇄대가 지나는 대단면 3련 터널이며 변단면 구간으로 1 : 4.5의 하향경사 및 상부 비탈면 형성에 따른 터널단면, 필러폭 그리고 터널 토피고가 연속적으로 변화하는 구간이다. 즉 터널직경이 점차 변하는 구간으로 필러폭이 직경에 따라 0.5D에서 1.0D로 변하므로 필러폭에 대한 각 단면에 대한 안정성 평가를 할 수 있는 구간이다. 3련 터널의 필러부 안정성을 계측치를 바탕으로 평가하였으며 이를 수치해석과 비교해 보았다. This research area is a greate section of triple tunnels that passes through the fault fractured zone the in the granite area. In this area, tunnel section, pillar width and overburden height are changed consecutively due to declivity of 1 : 4.5 and slope formation of upper part as changed section. That is, stability estimation for each section varying pillar width can be conducted because tunnel diameter changes gradually from 0.5D to 1.0D according to distance of pillar width. We have estimated the stability of pillar width in triple tunnels with monitoring value, and compared the stability with results of numerical analysis.

DEA를 활용한 국내 의무자조금단체 경영효율성 분석

김영수(Youngsue Kim),김성훈(Sounghun Kim) 한국농업경제학회 2018 農業經濟硏究 Vol.59 No.3

In 2002, Korean government introduced the check-off system and now Korea has 16 check-off boards including Korean beef, beef, pork, milk, chicken, duck, Korean ginseng, paprika, mandarin, and environment-friendly agricultural products. Basically, the check-off is one of the excellent ways to support farmer and thus Korean government have kept promoting the check-off boards. Even though many researchers studied about the Korean check-off, no study focuses on the management efficiency of check-off boards. The objective of this study is to measure the management efficiency of Korean check-off boards and to provide the benchmarking information that can improve the management efficiency of check-off board. DEA was used to analyze the management efficiency of 10 check-off boards in Korea. The results present the several findings as follows: The check-off boards of Korean beef, chicken, duck, and paprika show the inefficient management efficiency. Therefore, these check-off boards need to increase the management efficiency or the rate of check-off. Especially, these check-off boards might spend more check-off fund to manage the stability of supply-demand and to operate the other programs of check-off board, instead of advertisement and promotion which are the main programs of check-off board.

DEA를 활용한 시장도매인 경영효율성 분석 : 강서도매시장 시장도매인을 중심으로

김영수(Youngsue Kim),홍승지(Seungjee Hong),김성훈(Sounghun Kim) 한국농업경제학회 2021 農業經濟硏究 Vol.62 No.1

The agricultural market-wholesaler system was introduced to the Gangseo wholesale market in June 2004 and now 52 agricultural market-wholesalers were operating. As one of the important wholesale market players, agricultural market-wholesaler has been studied by many researchers. Most of the research papers focus on agricultural market-wholesaler, in order to discuss the market-purchasing system by comparing it with the auction system. However, the academic discussion about the management efficiency of agricultural market-wholesaler is rare. The purpose of this research is to analyze the management efficiency of agricultural market-wholesaler and to figure out the way of improving the management efficiency of agricultural market-wholesaler with inefficient management efficiency. DEA was used to analyze the agricultural marketwholesaler s management efficiency. According to the DEA analysis, 8 agricultural marketwholesaler were found to be efficient in management under CRS conditions, 12 agricultural market-wholesalers with efficient management under VRS conditions, and 8 agricultural marketwholesalers with efficient scale efficiency. As a result of analyzing management efficiency by using the Wilcoxon Rank Sum Test by dividing agricultural market-wholesalers into two groups, it was suggested that agricultural market-wholesalers can improve management efficiency by promoting projects that can improve relations with farmers who ship to agricultural marketwholesalers and enhance mutual cooperation.

On Board 형 엔진제어기 형상설계

김태진(Taejin Kim),김영수(Youngsu Kim),김규동(Kyudong Kim),김재용(Jaeyong Kim),김병현(Byunghyun Kim),김창휘(Changhuy Kim) 항공우주시스템공학회 2017 항공우주시스템공학회 학술대회 발표집 Vol.2017 No.4

고방열 복합소재 개발을 위한 고열전도성 액정성 에폭시 수지의 개발

김영수 ( Youngsu Kim ),정진 ( Jin Jung ),여현욱 ( Hyeonuk Yeo ),유남호 ( Nam-ho You ),장세규 ( Se Gyu Jang ),안석훈 ( Seakhoon Ahn ),이승희 ( Seung Hee Lee ),고문주 ( Munju Goh ) 한국복합재료학회 2017 Composites research Vol.30 No.1

에폭시 수지는 3차원 네트웍 구조를 갖는 대표적인 열경화성 수지이다. 최근 에폭시 수지의 네트웍 구조를 제어하여 새로운 기능성 에폭시를 개발하는 연구가 활발히 진행되고 있다. 특히, 액정성 에폭시를 대표로 하는 새로운 개질 에폭시는 랜덤한 형태의 네트웍 구조를 배향 구조로 변경함으로써, 기존의 에폭시로부터 얻을 수 없는 새로운 기능성 발현에 성공하고 있다. 본 논문에서는 액정성 에폭시 수지의 합성과 고방열성 복합재료로의 응용에 관하여 설명하였다. Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has three-dimensional random network, it possesses thermal properties like a typical heat insulator. Recently, there has been increasing interest in controlling the network structure for making new functionality from EP. Indeed, the new modified EP represented as liquid crystalline epoxy (LCE) is spotlighted as an enabling technology for producing novel functionalities, which cannot be obtained from the conventional EPs, by replacing the random network structure to oriented one. In this paper, we review current progress in the field of LCEs and their application for the highly thermal conductive composite materials.

선박에서 증강현실 위치 정합 활용을 위한 기계학습 기반의 마커 복원 방법 연구

김영수(Youngsu Kim),이경호(Kyungho Lee),한영수(Young-Soo Han),여현빈(Hyunbin-Yeo) (사)한국CDE학회 2022 한국CDE학회 논문집 Vol.27 No.4

The interior of the ship is very complex and the equipment is equipped with pipes, valves, supports, etc. In order to utilize augmented reality in such an environment, it is more appropriate to use markers rather than markerless, which creates a model based on the characteristics of the target equipment. However, it is difficult to apply the marker because a lot of corrosion or damage to the marker may occur in the ship. Therefore, in this study, when a marker is damaged, it is intended to restore the marker using GAN among machine learning techniques. At this time, the model was built using the Pix2Pix, Cycle GAN, and Disco GAN algorithms widely used for images among GAN algorithms. Finally, an efficient marker restoration algorithm was verified by qualitatively and quantitatively comparing the model results.

탄소함량에 따른 고망간강의 기계적 특성과 상변태

김영수(Youngsu Kim),이수열(Soo Yeol Lee) 한국기계가공학회 2019 한국기계가공학회 춘추계학술대회 논문집 Vol.2019 No.4

Korean EFL Learners` Knowledge of Polysemous Words in Relation to Word Frequency and Reading Proficiency

김영수 ( Youngsu Kim ),최문홍 ( Mun Hong Choe ) 한국현대영어영문학회 2015 현대영어영문학 Vol.59 No.3

The acquisition of polysemous words in a foreign language epitomizes the retention and representation of linguistic knowledge as well as its developmental dynamics. In this study, Korean high school students were asked to carry out two types of English vocabulary tasks: a word-in-isolation task and a word-in-context task. Each task was made up of three sets of polysemous words selected from 1000-, 2000-, and 3000-level frequency words, respectively. In addition, the students’ strategies for learning and determining the meanings of polysemous words were assessed through written questionnaires and class discussion. Overall, the students showed a higher rate of acquisition when measured by the word-in-context task than the word-in-isolation task, and they had greater difficulty identifying the meaning of less frequent polysemous words. Students relied more on memorized meanings when dealing with high-frequency polysems. When words were presented in isolation, the meanings of more frequent polysems were better recalled than less frequent ones. When words were presented in context, however, frequency was not proportionate to knowledge. All these observations suggest that differences in L2 learners’ knowledge of polysemous words lie not only in how many individual meanings they have memorized but in how well they make use of contextual cues and that as the learners’ reading proficiency develops, their vocabulary knowledge becomes contextualized to a greater extent. (Chonnam National University)