Core-shell 구조를 지니는 하모닉 분말의 성형거동 분석

주수현,박효욱,강수영,이언식,강희수,김형섭,Joo, Soo-Hyun,Park, Hyo Wook,Kang, Soo Young,Lee, Eon Sik,Kang, Hee-Soo,Kim, Hyong Seop 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.2

In this study, effect of core-shell structure on compaction behavior of harmonic powder is investigated. Harmonic powders are made by electroless plating method on Fe powders. Softer Cu shell encloses harder Fe core, and the average size of Fe core and thickness of Cu shell are $34.3{\mu}m$ and $3.2{\mu}m$, respectively. The powder compaction procedure is processed with pressure of 600 MPa in a cylindrical die. Due to the low strength of Cu shell regions, the harmonic powders show better densification behavior compared with pure Fe powders. Finite element method (FEM) is performed to understand the roll of core-shell structure. Based on stress and strain distributions of FEM results, it is concluded that the early stage of powder compaction of harmonic powders mainly occurs at the shell region. FEM results also well predict porosity of compacted materials.

고압비틀림 성형 공정에 의한 Al 분말의 초미세결정 벌크화 및 특성 평가

주수현,윤승채,이종수,김형섭,Joo, Soo-Hyun,Yoon, Seung-Chae,Lee, Chong-Soo,Kim, Hyong-Seop 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.1

Bulk nanostructured metallic materials are generally synthesized by bottom-up processing which starts from powders for assembling bulk materials. In this study, the bottom-up powder metallurgy and High Pressure Torsion (HPT) approaches were combined to achieve both full density and grain refinement at the same time. After the HPT process at 473K, the disk samples reached a steady state condition when the microstructure and properties no longer evolve, and equilibrium boundaries with high angle grain boundaries (HAGBs) were dominant. The well dispersed alumina particles played important role of obstacles to dislocation glide and to grain growth, and thus, reduced the grain size at elevated temperature. The small grain size with HAGBs resulted in high strength and good ductility.

비정형 데이터와 딥러닝을 활용한 내수침수 탐지기술 개발

이하늘,김형수,김수전,김동현,김종성 한국수자원학회 2021 한국수자원학회논문집 Vol.54 No.12

In this study, a model was developed to determine whether flooding occurred using image data, which is unstructured data. CNN-based VGG16 and VGG19 were used to develop the flood classification model. In order to develop a model, images of flooded and non-flooded images were collected using web crawling method. Since the data collected using the web crawling method contains noise data, data irrelevant to this study was primarily deleted, and secondly, the image size was changed to 224×224 for model application. In addition, image augmentation was performed by changing the angle of the image for diversity of image. Finally, learning was performed using 2,500 images of flooding and 2,500 images of non-flooding. As a result of model evaluation, the average classification performance of the model was found to be 97%. In the future, if the model developed through the results of this study is mounted on the CCTV control center system, it is judged that the respons against flood damage can be done quickly. 본 연구에서는 비정형 데이터인 사진자료를 이용하여 침수의 발생여부를 판단하는 모델을 개발하였다. 침수분류를 모델 개발을 위하여 CNN기반의 VGG16, VGG19을 이용하였다. 모델을 개발하기 위하여 침수사진과 침수가 발생하지 않은 사진을 웹크롤링 방법을 이용하여 사진을 수집하였다. 웹크롤링 방법을 이용하여 수집한 데이터는 노이즈 데이터가 포함되어 있기 때문에 1차적으로 본 연구와 상관없는 데이터는 소거하였으며, 2차적으로 모델 적용을 위하여 224 × 224로 사진 사이즈를 일괄 변경하였다. 또한 사진의 다양성을 위해서 사진의 각도를 변환하여 이미지 증식을 수행하였으며. 최종적으로 침수사진 2,500장과 침수가 발생하지 않은 사진 2,500장을 이용하여 학습을 수행하였다. 모델 평가결과 모델의 평균 분류성능은 97%로 나타났으며. 향후 본 연구결과를 통하여 개발된 모델을 CCTV관제센터 시스템에 탑재한다면 신속하게 침수피해에 대한 대처가 이루어 질 수 있을 것이라 판단된다.

베이비붐세대 사회공헌활동지원사업의 가치 평가

주수현(Joo, Soo-Hyun),김수영(Kim, Soo-Young),진재문(Jin, Jae-Moon) 한국지방정부학회 2016 지방정부연구 Vol.20 No.2

본 연구의 목적은 베이비붐 세대의 사회공헌활동사업에 대한 중요성을 파악하기 위해 가치를 추정하고 향후 사업의 확대 여부를 판단하기 위해 타당성을 검토하는 것이다. 화폐가치는 시장에서 거래되지 않는 공익적 사업에 대해 주로 적용하는 조건부 가치측정 방법(contingent valuation method)으로 추정하였다. 271명에 대해 이중경계형(double-bounded dichotomous choice: DB-DC) 로그로짓형모형(log-logistic model)으로 추정한 결과, 3개 기관의 1시간당 WTP에 대푯값이 상이하게 나타났다. 3개 기관 평균으로 산정한 중위값은 1,228.8원, 절단평균은 5,128.5원, 평균은 6,550.4원으로 추정되었으며 대푯값뿐만 아니라 기관 간에도 차이가 나타났다. 3개 기관에 대한 타당성을 보면, C 기관에서만 비용편익비율이 1을 초과한 것으로 나타났다. 이 기관은 다른 기관에 비해 수강시간이 길고 참여자 수가 많아 규모의 경제가 작용한 것으로 보인다. 연구결과를 근거로, 향후 본 사업 시행에서는 충분한 사전기획을 통해 사회공헌활동사업의 내용을 보다 내실있게 마련하고, 기관별로 참여자를 확대하는 방안을 모색하며, 기관의 규모나 특성에 맞게 사업이 진행되도록 예산지원을 해줄 필요가 있다고 판단된다. This study attempted to identify an importance of the baby boom project through conducting a research and evaluating the outcomes. As a result, this study adopted feasibility study design. Thus, the major purpose of this study is to provide an empirical grounds whether the baby boom research expands in the future. For this purpose, the monetary value of the public business model was estimated by applying contingent valuation method. WTP was calculated by using log-normal model based on double-bounded dichotomous choice(DB-DC). The median WTP and the truncated mean per hour was estimated 1,228.8 won, 5,128.5 won respectively. The mean WTP per hour was recorded for 6,550.4 won. These results obtained through analysing answers from 271 baby boomers. This study applied the same method to three community welfare centers. The community welfare center, which showed effectiveness of the project, had the following characteristics: the C center with relatively high level of field expertise and large-scale. This type of the agency exceeded 1 in the cost versus benefit ratio. This outcome indicates a positive possibility to expand the project. Furthermore, it suggests that an advance planning, which adjusts to characteristics of each agency, is necessary.

롯데 자이언츠 팀의 승률과 관중 관계 및 지역경제 파급효과 분석

주수현(Joo Soo-Hyeon),유영명(Yoo Young-Myung) 한국지역사회학회 2010 지역사회연구 Vol.18 No.4

This paper investigates regional economic effects of the Lotte Giant Team using a multi-regional input-output(MRIO) model. Home game of The Busan-based Lotte Giant, as Pro Baseball game, is an ambitious project to develop Busan to be an advanced international and worldwide city. The result of this analysis shows that the efficiency of the home game is proved very high. The event could generate 110,870 million won of output, 48,905 million won of added value, and 2,359 persons of employment throughout the nation. In the South-east Area, the event could generate 76,020 million won of output, 32,953 million won of added value and 1,800 persons of employment. Focusing on Busan, the event could generate 62,622 million won of output, 27,266 million won of added value and 1,566 persons of employment. Thus, sports event can make a successful contribution to the economic development of a city. We expect that this study will be a helpful case for similar studies and at the same time a reference resource for analysis concerned. Especially it will help those who consider the sports event to be non-productive and consumptive correct their prejudices. It is desirable that estimation of the sports event be expanded to Performance Analysis from the industrial production growth.

Microstructure and tensile behavior of Al and Al-matrix carbon nanotube composites processed by high pressure torsion of the powders

주수현(Soo-Hyun Joo),김형섭(Hyong Seop Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5

Carbon nanotubes (CNTs) are expected to be ideal reinforcements of composite materials used in aircraft and sports industries due to their high modulus and low density. In the present paper, severe plastic deformation by high pressure torsion (HPT) of powders at elevated temperature (473 K) was employed to achieve both powder consolidation and grain refinement of aluminum-matrix nanocomposites reinforced by 5 vol% CNTs. Before the HPT, the powders were ball milled using planetary ball mill in order to achieve molecular level mixing. Aluminum was treated by the same process for a reference. The HPT processed disk were composed of mostly equilibrium grain boundaries with high misorientation angles. The CNT reinforced ultrafine grained microstructural features resulted in high strength and good ductility.

포스트 APEC의 지역경제 파급효과 분석

주수현(Soo hyeon Joo),유영명(Yoo Young-myung),김형빈(Kim Hyungbin) 21세기정치학회 2005 21세기 정치학회보 Vol.15 No.3

This study aims to help establish strategies to host mega events in Busan by continuously analysing outcome of post-APEC projects. It also seeks its objects of maximizing and, further, keeping up APEC impact on host-city by developing post-APEC projects in many sides. In analyzing the impact on regional economy, the research presents post-APEC development plans to maximize the regional economy Busan is now more than ready to host the APEC 2005 expecting opportunity to show the name of Busan to the worldin terms of rich culture, tourism and economics as well as diverse aspects of the city. During the APEC 2005 meetings and related events, Busan will receive very large flows of visitors, including APEC leaders and all other delegates, reaching 15,000 people. When the economic effect of the APEC 2005 is compared with that of other special grand events (e.g. the 14th Asian Games, 2002 FIFA World Cup), it exceeds the effect of those at the production multiplier effect, the value added multiplier effect and the employment effect. The purpose of this article is to investigate the Regional Linkage Effects of APEC 2005 in BUSAN using regional input-output model.

지역사회 시니어클럽 특성별 상대적 효율성 분석

주수현(Joo, Soo Hyun),김수영(Kim, Soo Young),박재영(Park, Jae Young),문경주(Moon, Kyung Joo) 한국지역사회학회 2017 지역사회연구 Vol.25 No.3

The purpose of this study is to estimate the relative efficiency of the senior clubs that have played a central role in the elderly job program, and to investigate the efficiency difference. The model is divided into two : public interest seeking type and startup promotion type according to the characteristics difference and regress the determinants of efficiency as Tobit model and derive the policy implication. The efficiency of 35 senior clubs according to the type of business, type of corporation, the ratio of public benefit and entrepreneurial budget, and whether or not to support central government subsidy were analyzed. The result shows significant differences statistically in the ratio of utilities budget to entrepreneurship and local government budget. The total efficiency of the group with the public utility type budget ratio was higher by 0.8982 than that of the business type. The efficiency of the group operated by the local government support budget alone was 0.8968. The IRS type accounted for 14.29% (5 DMUs) of the senior club, CRS type of 37.14% (13 DMUs) and IRS type of 48.57% (17 DMUs). Regression analysis by the Tobit model showed that the higher the institutional satisfaction, the higher the efficiency. Based on the results, we propose a plan to improve efficiency in terms of economies of scale for senior clubs with a high proportion of publicly – funded budgets compared to entrepreneurship and senior clubs operated solely with local government supportive funds.

부산지역 섬유,패션기업의 공간근접성에 따른 효율성 분석

주수현 ( Soo Hyeon Joo ),이선영 ( Sun Young Lee ),김영재 ( Young Jae Kim ) 국제지역학회 2008 국제지역연구 Vol.12 No.3

This paper investigates the properties and relative importance of Apparel Textile industry of Busan in terms of both the number of employees and the value-added, and then analyzes the relative technical efficiencies from the perspectives of space closeness such as consumption market, suppliers, living standards and clustering environments using the DEA model. The main outcomes are as follows. The Apparel Textile industry is still a key industry in Busan with relatively high intensity and high LQ (greater than one) in spite of the recent decrease between 2000 and 2005 both in the number of employees and the value-added. Those firms with consumption market showed higher efficiency in all kinds of efficiencies than the firms without the market, and further relatively higher efficiency than the firms with suppliers. In addition, the firms located in the higher living standards also showed higher values of efficiency compared with the firms in lower living standards. The policy implication from the results is that the strategic and selective investment should be made according to the relative efficiency and thus the traditional industry should be transformed to the high value added one with additional investment to utilize the scale efficiency.

고압비틀림 성형 공정에 의한 Al 기지 CNT 복합재료의 초미세결정 벌크화

주수현(S. H. Joo),김형섭(H. S. Kim) 한국소성·가공학회 2010 소성가공 : 한국소성가공학회지 Vol.19 No.7