• 해양환경안전학회지
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• 제28권7호
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• pp.1267-1273
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• 2022

최근 한국 조선업계가 세계 선박 발주 물량의 대부분을 수주하고 있지만, 생산 현장에서는 인력난으로 생산공정 차질을 겪고 있다. 오랜 조선업 불황으로 일감과 임금 모두 줄어든 탓에 근로자들이 조선소를 떠났기 때문이다. 수주가 증가한 주요 요인은 카타르 LNG선 대량 발주였으며, 선박에 요구되는 기술 사양이 복잡해지는 상황도 유리하게 작용하고 있다. 선박은 계약한 인도 시점이 무엇보다도 중요하기 때문에, 조선소의 주요 공정 중 도크 진수 계획이 무엇보다도 중요한 관리 아이템이다. 도크에서 건조되는 구조물은 의장 작업을 남긴 선체 혹은 완성형 선박일 수 있으며, 때에 따라서 선체의 일부 블록 수준일 경우도 많다. 진수 시, 선체는 유체력에 의한 호깅(hogging) 혹은 새깅(sagging) 모멘트 영향을 받게 되고, 블록 연결부의 구조강도에 대한 안전성 확보가 무엇보다도 중요하다. 정상적인 공정이라면 연결 부재는 용접을 끝낸 상태에서 진수하지만, 실제 조선사에서는 도크 일정을 준수하기 위하여 구조 안전성이 확보되는 조건에 대한 빠른 의사결정이 필요하다. 본 연구에서는 앞서 언급한 문제점들을 엔지니어링 관점에서 합리적으로 판단하기 위하여 휨 응력평가법과 유한요소해석 모델링을 사용한 상세 해석법과 적용성을 분석하였다. 논문에서 언급된 주요 내용은 향후 유사 구조 강도 평가의 진행 시 좋은 사례로 활용될 수 있을 것으로 생각한다.

• 유통과학연구
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• 제12권2호
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• pp.73-79
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• 2014

Purpose - The Korean government has revised the distribution industry development law to regulate large-scale retailer operations to protecting medium- and small-scale retailers and traditional markets. According to the revised law, large-scale retailers must follow regulations on operating hours and compulsory store closures two days per month. Based on the revised distribution industry development law, most local governments regulate operation hours and they have adopted compulsory closure programs for large-scale retail stores. However, it is argued that fresh food producers suffer from a decrease in sales based on the compulsory closure of stores operated by large-scale retailers. Large-scale retailers reduce their fresh food orders from agricultural and fishery producers because of the compulsory store closures. Fresh food producers also suffer from a decrease in prices because reduced orders lead to a decrease in auction prices based on the availability of excess goods in wholesale markets. This paper investigates the effects of operation regulations for large-scale retailers on agricultural producers by surveying agricultural and fishery producer organizations. Research design, data, methodology - A survey was conducted on 117 producer organizations of fruits and vegetables, cereals, fisheries, and livestock products from September 10 to October 4, 2012. Survey items are annual sales, shares of sales accounted for by large-scale retailers, reduction of orders and prices from large-scale retailers, methods to deal with the sales reduction, unfair trade practices of large-scale retailers, opinion of the large-scale retailer regulations, and so on. The average sales of the sampled producer organizations are 13.7 billion won and the average share of sales accounted for by large-scale retailers is 35.4%. Results - Survey results show that the sample producer organizations' sales decreased 10.1% because of the compulsory closures of stores operated by large-scale retailers. It is estimated that the total sales of producer organizations decreased 371.2 billion won because of the regulations on the operation of large-scale retailers. In addition to the direct effect of a sales decrease due to order reduction, agricultural and fishery producer organizations suffered from the secondary effect of price reduction in wholesale markets. When orders from large-scale retailers decreased, most agricultural and fishery producer organizations shipped redundant products to wholesale markets, decreasing auction prices. It was estimated that the price received decreased 21.9% when sold in other marketing channels. As producer organization sales decreased, it was reported that the labor force employed by producer organizations also decreased by 15.1%. Therefore, we can conclude that the regulations for large-scale retailer operations resulted in negative impacts on agricultural producers. Conclusions - Although the sales reduction due to the regulations for large-scale retailer operations are not great, the cumulative effects due to the continued compulsory closure of stores operated by large-scale retailers could be great. This paper suggests governmental programs that could help agricultural producer organizations to find new and effective marketing channels such as direct marketing, farmers' markets, exports, Internet shopping, and so on.

• 생명과학회지
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• 제27권6호
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• pp.661-672
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• 2017

내생균류는 숙주식물 내에서 생물학적 그리고 비생물학적 스트레스로부터 저항성을 갖는데 도움을 준다. 수생식물은 수생환경에 서식하며 육상식물보다 수분스트레스에 더 많이 노출되어있다. 본 연구에서는 제주에 있는 남생이못, 수장동습지, 용수저수지, 강정천 4개의 습지에서 11개의 수생 수변식물을 채집하여 연구하였다. 전처리를 통해 식물 외생균을 제거하고 뿌리에서 내생균류를 분리하였다. 남생이못에서 126균주, 수장동습지에서 22균주, 용수저수지에서 44균주, 강정천에서 32균주가 분리되어 총 224개의 내생균류를 분리하였다. 분리된 균은 ITS를 이용해 동정한 후, 다양성 분석을 하였다. 남생이못에서 분리된 내생균류는 4개 문(Phylum), 7개 강(class), 12개 목(order), 19개 과(family), 30개 속(genus)로 구분되었다. 수장동습지에서 분리된 내생균류는 4개 문, 5개 강, 6개 목, 11개 과, 11개 속으로 구분되었으며, 용수저수지에서 분리된 내생균류는 4개 문, 5개 강, 7개 목, 12개 과, 13개 속으로 구분되었다. 강정천에서 분리된 내생균류는 1개 문, 2개 강, 5개 목, 7개 과, 9개 속으로 구분되었다. 4개의 습지에서 공통으로 분리된 속은 Alternaria속, Colletotrichum속, Fusarium속이었다. 향후 내생균류의 다양한 생태학적 분포와 다양성 규명에 대한 연구에 기초자료로 이용될 것이다.

• 응용통계연구
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• 제33권2호
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• pp.147-160
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• 2020

본 논문은 시계열 일반화 선형 모형의 하나인 계수형 시계열 모형에서 중요한 역할을 하는 과거 관측값과 조건부 평균값의 차수를 자동으로 결정하는 알고리즘을 연구한다. 본 알고리즘은 ARIMA 모형의 차수를 기반으로 시계열 일반화 선형 모형의 차수 후보군을 만들고, 차수 후보군의 조합을 이용하여 정보량 기준으로 최종 모형으로 선택한다. 제안된 알고리즘을 평가하기 위하여, 내재적 모형 및 내재적 시계열의 종류에 따른 시뮬레이션 및 실증 분석을 수행하고 예측력을 ARIMA 모형과 비교한다. 예측 성능 평가 결과, 계수형 시계열 분석에서 ARIMA 모형에 비해 시계열 일반화 선형 모형의 예측 성능이 우수함을 확인할 수 있다. 또한 실증분석으로서, 살인사건 발생 건수의 예측결과 ARIMA 모형보다 중기 및 장기 예측에서 우수한 성능을 나타내는 것을 확인할 수 있다.

• 한국환경과학회지
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• 제22권12호
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• pp.1551-1559
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• 2013

This study was conducted to compare benthic macroinvertebrate communities of urban stream and nature stream in Daegu-si, Gyeongju-si, Gyeongsan-si, Andong-si, and Cheongsong-gun. The survey was carried out with 12 points in total six points for urban stream, six points for nature stream from Sept. 2011 to July 2012. In the urban stream were 33 species belonged to 24 families, 11 orders, 7 classes and 4 phyla while in the nature stream were 73 species belonged to 38 families, 12 orders, 5 classes and 4 phyla. In general, species diversity indices and species richness indices appeared low in urban stream but dominance indices was high. Functional feeding groups and Habitat Oriented Groups appeared comparatively simple in urban stream rather than nature stream. As a result of analysis of community stability, species included to area I and area III equally appeared in nature stream while species included to area I mostly appeared in urban stream. An analysis of the correlation between the population density and the number of species, the population number and biological indicators such as DI, H', RI, and ESB revealed that there was a significant correlativity with the diversity index and a very high correlativity with the number of species, abundance index and the ESB. On the other hand, the population number and the dominance index did not reveal any correlativity. For indicator species, Hydroptila KUa, Physa acuta appeared in urban stream while Paraleptophlebia chocolata, Epeorus pellucidus appeared in nature stream.

• Structural Engineering and Mechanics
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• 제34권6호
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• pp.779-799
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• 2010

In order to consider high-order effects on the actual limit state function, a new response surface method is proposed for structural reliability analysis by the use of high-order approximation concept in this study. Hermite polynomials are used to determine the highest orders of input random variables, and the sampling points for the determination of highest orders are located on Gaussian points of Gauss-Hermite integration. The cross terms between two random variables, only in case that their corresponding percent contributions to the total variation of limit state function are significant, will be added to the response surface function to improve the approximation accuracy. As a result, significant reduction in computational cost is achieved with this strategy. Due to the addition of cross terms, the additional sampling points, laid on two-dimensional Gaussian points off axis on the plane of two significant variables, are required to determine the coefficients of the approximated limit state function. All available sampling points are employed to construct the final response surface function. Then, Monte Carlo Simulation is carried out on the final approximation response surface function to estimate the failure probability. Due to the use of high order polynomial, the proposed method is more accurate than the traditional second-order or linear response surface method. It also provides much more efficient solutions than the available high-order response surface method with less loss in accuracy. The efficiency and the accuracy of the proposed method compared with those of various response surface methods available are illustrated by five numerical examples.

• 한국의상디자인학회지
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• 제12권4호
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• pp.1-13
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• 2010

The purpose of this study is to examine the different preference as well as the factor for this preference between general internet shopping mall and feminine internet fashion shopping mall only which are subjected with women and know the satisfaction which follows hereupon. This research will help to establish the strategy to marketers who manage feminine internet fashion shopping mall. The results of this study as follows; 1. As the result of the analysis of preference factors for general internet shopping mall, it was classified with, convenient characteristic, economical efficiency, product and information characteristic, sales promotion, and customer service. Also differences among preference factors appear with following orders, economical efficiency, convenient characteristic, product and information characteristic, sales promotion, and customer service. 2. As the result of the analysis of preference factor for feminine internet fashion shopping mall, it was classified with, fashion information and style, purchase product, economical efficiency, product assortment, and customer service. Also differences among preference factors appear with following orders, fashion information style, product assortment, purchase product, economical efficiency, and customer service. 3. As the result of the analysis of preference factors, convenient characteristic and product information mostly effects to satisfy the customers who use general internet shopping mall. Also purchase product, product assortment, fashion information and style mostly effects to satisfy the customers who use feminine internet fashion shopping mall.

• 비파괴검사학회지
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• 제19권3호
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• pp.200-206
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• 1999

광탄성법을 이용하여 인장하중을 받는 곡선보의 중앙에서 하중축과 직교하는 일직선상에 축방향 응력성분을 측정하였다. 광탄성 데이터의 정밀 측정을 위하여 영상처리 시스템을 이용, 원래의 프린지를 명시야 배열과 암시야 배열의 등색선프린지로부터 2배로 증식시키고 세선처리를 하였다. 세선처리된 광탄성 영상으로부터 1/4차수(N=0. 1/4, 2/4. 3/4. 1, 5/4...)마다 프린지 차수를 읽을 수 있으므로 정확한 위치에서 정량적인 측정이 가능하다. 광탄성 실험에서 곡선보의 인장 하중을 3종류로 변화하였을 때 이론식에 의한 응력분포와 일치하는 경향을 나타냈으나, 장탄성법에 의한 측정결과는 이론값과 8%이내의 차이가 나타났다. 이러한 원인은 광탄성 시험편 가공시 하중축과 치수가 이론식에 적용된 조건과 다소 상이한 것으로 판단되며, 정밀하게 가공된 시험편을 사용하여 측정할 경우 실험에 의한 오차는 감소될 것으로 추정된다. 이 실험으로부터 광탄성법에 의한 응력측정시 프린지 증식 및 세선처리 기법을 적용할 경우 정밀한 응력측정이 가능함을 확인할 수 있었다.

• Structural Monitoring and Maintenance
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• 제5권2호
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• pp.173-187
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• 2018

Performance evaluation of RC frame building by nonlinear static pushover analysis that accounts for elastic and post elastic behavior is becoming very popular as a valid decision making tool in seismic hazard resistant designs. Available literature suggests great amount of interest has shown by researchers in suggesting refinements to geometric and material modelling to bridge the gap between analytical predictions and observed performances. Notwithstanding the attempts gaps still exists. Sequence of plastic hinge formation which has great influence on pushover analysis results is an area less investigated. This paper attempts to highlight the importance of hinge sequence considerations to make analysis results more meaningful. Variation in analysis results due to different hinge sequences have been quantified, compared and bounds on analysis results have been presented.

• 진공이야기
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• 제2권2호
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• pp.17-23
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• 2015

Medium Energy Ion Scattering (MEIS) has been successfully used for ultrathin film analysis such as gate oxides and multilayers due to its single atomic depth resolution in compostional and structural depth profiling. Recently, we developed a time-of-flight (TOF) MEIS for the first time, which can analyze a $10{\mu}m$ small spot. Small spot analysis would be useful for test pattern analysis in semiconductor industry and various thin film technology. The ion beam damage problem is minimized due to its improved collection efficiency by orders of magnitude and the ion beam neutralization problem is removed completely for quantitative analysis. Newly developed TOF-MEIS has been applied for gate oxides, ultra shallow junctions, nanoparticles, FINFET structures to provide compositional and structural profiles. Further development for submicron spot analysis and applications for functional nano thin films and nanostructured materials are expected for various nanotechnology and biotehnology.