A Genetic Algorithm Approach for Logistics Network Integrating Forward and Reverse Flows

고현정,고창성,정기호,Ko, Hyun-Jeung,Ko, Chang-Seong,Chung, Ki-Ho 대한산업공학회 2004 산업공학 Vol.17 No.S

As today's business environment has become more and more competitive, forward as well as backward flows of products among members belonging to a supply chain have been increased. The backward flows of products, which are common in most industries, result from increasing amount of products that are returned, recalled, or need to be repaired. Effective management for the backward flows of products has become an important issue for businesses because of opportunities for simultaneously enhancing profitability and customer satisfaction from returned products. Since third party logistics service providers (3PLs) are playing an important role in reverse logistics operations, they should perform two simultaneous logistics operations for a number of different clients who want to improve their logistics operations for both forward and reverse flows. In this case, distribution networks have been independently designed with respect to either forward or backward flows so far. This paper proposes a mixed integer programming model for the design of network integrating both forward and reverse logistics. Since the network design problem belongs to a class of NP-hard problems, we present an efficient heuristic algorithm based on genetic algorithm (GA), of which the performance is compared to the lower bound by Lagrangian relaxation. Finally, the validity of proposed algorithm is tested using numerical examples.

패혈증 및 패혈성 쇼크로 진단 받은 소아 중환자에서 vitamin protocol의 효과 비교

고현정,정민재,김재송,손은선,유윤미,Ko, Hyun Jung,Jung, Min Jae,Kim, Jae Song,Son, Eun Sun,Yu, Yun Mi 한국임상약학회 2020 한국임상약학회지 Vol.30 No.3

Background: Recently, a study comprising adult patients with sepsis admitted in the intensive care unit (ICU) was conducted. The patients were treated with high doses of intravenous ascorbic acid, thiamine, and hydrocortisone; the clinical outcomes demonstrated significant therapeutic benefits. The mortality rate in children with sepsis is approximately 25%. However, the effects of additional treatment with ascorbic acid and thiamine ("vitamin protocol") in children are rarely investigated. Methods: A retrospective analysis was performed using medical records of patients diagnosed with sepsis and admitted to the pediatric ICU (PICU) between September 2016 and June 2019. The control group received treatment only as per sepsis protocol, whereas the treated group received both sepsis protocol and the vitamin protocol. The primary endpoint was change in Vasoactive-Inotropic Score (VIS) for 5 days. The secondary endpoints included the length of stay in the PICU, duration of using mechanical ventilators and vasopressors, and mortality rate. Results: The number of patients in the treated and control groups was 33 and 24, respectively. The treated group showed greater decrease in their VIS for 5 days than the control group (44.4 vs 18.6); however, the difference was not statistically significant. The length of stay in the PICU was significantly longer for the treated group than for the control group [10.0 days (Interquartile range (IQR), 6-18) vs 4.5 days (IQR, 4-10.3); p=0.004]. Conclusions: No significant treatment benefits were observed following vitamin protocol administration to the pediatric patients with sepsis. Further studies are necessary for improving the efficacy and safety of the vitamin protocol.

컨테이너터미널 운영사의 기업경쟁력 평가에 관한 연구

고현정,길광수,Ko, Hyun-Jeung,Kil, Kwang-Soo 한국항해항만학회 2011 한국항해항만학회지 Vol. No.

본 연구는 최근 우리나라 항만 물동량 증가세가 둔화되고 있는 가운데 국내 컨테이너터미널 운영기업의 경쟁력 강화를 위한 방안을 마련하고자 기업경쟁력 평가모형을 제시하고 글로벌 터미널 운영사와 비교분석하였다. 기업경쟁력 분석을 위한 퍼지모형은 퍼지이론과 AHP를 활용하였다. 경쟁력 평가를 위한 계층적 구조는 SERM 모형을 활용하였는바, 이는 기업의 성장이 주체(Subject), 환경(Environment), 자원(Resource), 그리고 메커니즘(Mechanism)의 상호작용 과정에서 형성된다는 논리에 바탕을 두고 있다. 분석결과 우리나라 컨테이너터미널 운영기업의 경쟁력은 글로벌 기업에 비해 전반적으로 약한 것으로 나타났다. 특히 기업의 대형화, 사업 다각화, 글로벌 전략수립이 시급한 것으로 나타났다. As the annual growth rate of port handling container volume in Korea has faced slowdown, this paper attempts to find strategies for the domestic container terminal operators in order to enhance competitiveness. For this, the model of using AHP and the fuzzy set theory is used for evaluating competitiveness between domestic and global container terminal operators. The evaluation model hierarchy is developed based on SERM(subject-environment-resource-mechanism) theory of business strategy. The results show domestic operators are ranked lower than global player so that they particularly pay attention to the areas of scale of economy, business diversification, and globalization strategy.

해상풍력 전용항만 입지선정 평가항목에 관한 연구

고현정,Ko, HyunJeung 한국항만경제학회 2012 韓國港灣經濟學會誌 Vol.28 No.3

세계 각국은 신재생 에너지 가운데 해상풍력 발전에 국가적 역량을 집중하면서 해상풍력 터빈의 용량을 대형화하고 있다. 특히 해상풍력 터빈은 부피와 중량이 큰 특징이 있어 육상운송에 어려움이 있어 해상풍력 전용항만이 필요하다. 따라서 본 연구에서는 국내 해상풍력 단지가 성공적으로 조성 및 운영될 수 있도록 최적의 전용항만 입지선정에 영향을 끼치는 평가항목을 분석하여 국가정책 의사결정에 올바른 방향을 제시하고자 하였다. 이를 위해 Fuzzy-AHP 기법을 적용하여 평가항목 별 중요도를 도출하였다. 평가항목은 수준 I에서는 5가지, 즉 집적 요인, 지역 요인, 경제 요인, 입지 요인, 컨소시엄 요인이 선정되었다. 이 가운데 집적 요인 37.4%, 입지 요인 34.2%, 경제 요인 24.5%가 주요한 항목으로 분석되었다. 그리고 수준 II에서는 각 요인에 3가지 항목이 선정되어 모두 15개 평가항목이 선정되었다. 분석 결과를 보면, 해상풍력 전용항만 입지 선정에 있어서 핵심적으로 고려되어야 할 항목은 풍력산업의 집적도, 항만운영의 경제성을 확보하는 물동량 규모, 해상풍력 관련 산업의 발달 정도, 그리고 개발될 해상풍력 단지와의 근접성으로 나타났다. 즉 해상풍력 전용항만 건설은 항만건설 측면과 해상풍력 터빈 제조기업의 입지 선호지역을 복합적으로 고려해야 한다는 의미이다. 따라서 정부가 해상풍력 전용항만을 건설함에 있어서 풍력터빈 제조기업의 의견을 충분히 반영하는 것이 요구된다. The offshore wind farm is increasingly attractive as one of future energy sources all over the world. In addition, the capacity of an offshore wind turbine gets larger and its physical characteristics are big and heavy. In this regard, a special port is necessary to assemble, store, and transport the offshore wind systems, supporting to form the offshore wind farms. Thus, this study aims to provide a policy maker which evaluation factors can significantly affect to the optimal site selection of a offshore wind port. For this, Fuzzy-AHP method is applied to capture the relative weights. The results of this study can be summarized as follows. Five criteria in level I was defined such as the accumulation factor, the regional factor, the economic factor, the location factor, and the consortium factor. Of these, the accumulation factor(37.4%), the location factor(34.2%), and the economic factor( 24.5%) were analyzed by major factors. In level II, three assessment items of each factor were selected so that total fifteen items were formed. To sum up, the site selection of offshore wind port should consider the density of the wind industry, cargo volume of securing the economic operation of terminals, the development degree of offshore wind related industry, and the proximity to the offshore wind farms. In other words, the construction of offshore wind port should be paid attention to considering not only the proximity to offshore wind farms but also the preference of turbine manufacturing companies.

Porphyromonas endodontalis의 lipopolysaccharide가 치주인대 섬유아세포의 CC Chemokines 성성에 미치는 영향

고현정,이상엽,이우철,백승호,배광식,임성삼,KO Hyun-Jung,Lee Sang-Yup,Lee Woo-Chul,Baek Seung-Ho,Bae Kwang-Sik,Lim Sung-Sam 대한치과의사협회 2005 대한치과의사협회지 Vol.43 No.12

이 연구의 목적은 치수 및 치근단 조직의 감염의 주요 원인들이 Porphyromonas endodontalis의 LPS가 치주인대 섬유아세포의 MCP-1 MIP-1α 그리고 RANTES의 생성에 미치는 영향을 관찰함으로써 치근단 염중의 발병에서 섬유아세포의 역할을 알아보는 것이다. 혐기성 조건에서 배양한 P. endodontalis와 E. coil의 LPS를 추출, 정제한 후, 치주인대 섬유아세포 0.01, 0.1, 1, 10ug/ml 농도의 P. endodontalis와 E. coil의 LPS로 12, 24, 48시간 동안 자극하였다. MCP-1, MIP-1α 그리고 RANTES의 단백질 농도는 ELISA를 이용하여 분석하였다. 이연구의 결과는 아래와 같다. 1. P. endodontalis의 LPS로 자극시킨 치주인대 섬유아세포에서 분비된 MCP-1의 수준은 시간과 농도에 비례하여 증가하였다. 2.E.coil의 LPS로 자극시킨 치주인대 섬유아세포에서 분비된 MCP-1의 양도 시간에 비례하여 증가함을 보였다. 이는 P. endodontalis LPS보다 통계적으로 유의성있게 많은 양을 나타냈다.(p<0.05) 3. 치주인대 섬유아세포에서 MIP-1α 과 RANTES는 거의 분비되지 않았다. 이 연구에서 세균의 LPS로 자극시 치주인대 섬유아세포 MCP-1의 강한 발현은 만성 치근단 염증의 초기에 단핵세포와 대식세포의 recruitment를 증가시키는 것고 관련되어지는 것으로 보인다.

치과용 바렐연마기의 연마시간에 따른 Co-Cr 합금의 표면거칠기 관찰

고현정,박유진,최성민,Ko, Hyeon-Jeong,Park, Yu-Jin,Choi, Sung-Min 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.3

Purpose: The aim of this study was to observe the surface roughness and surface topography of cobalt-chrome (Co-Cr) alloys with grinding time in dental barrel finishing. Methods: This study involved two types of Co-Cr alloys. Specimens were manufactured with the dimensions 10×10×2 mm. Each specimen was cast according to the manufacturer's instructions. The cast alloys were polished for 35 minutes at intervals of five minutes in an automatic barrel finishing. Specimens were imaged with a three-dimensional optical microscope to measure surface roughness. Results: BC specimens and GM specimens had the highest roughness (Ra) values in the ungrained control group, and the lowest Ra values were measured 20 minutes after grinding. Conclusion: The best conditions for grinding Co-Cr alloy using a dental barrel finishing were a weight ratio of polishing media, water, and compound of 150 g:200 g:5 g, and a rotation speed of 450 rpm. Grinding time to obtain appropriate surface roughness should be limited to 15 to 30 minutes.

토픽 모델링을 활용한 라스트마일 배송의 논제 분석

고현정(Ko, Hyun Jeung),손영환(Sohn, Young Hwan) 한국상품학회 2021 商品學硏究 Vol.39 No.5

온라인 전자상거래의 발전과 코로나19 팬데믹시대에 라스트마일 배송의 수요가 증가하고 있다. 하지만 물류비용 측면에서는 비효율성이 높은 구간으로 수익성을 확보하기 위한 기술 혁신이나 다양한 전략이 요구된다. 따라서 본 연구에서는 토픽 모델링 기법을 적용하여 라스트마일 배송 관련 연구의 핵심 논제를 분석하여 새로운 시사점을 제공하고자 하였다. 연구 결과의 시사점은 다음과 같다. 첫째, 단어의 빈도 분석을 통해 라스트마일 배송은 고객, 시간, 비용이 중요한 키워드임을 확인하였다. 둘째, 단어의 유사도 분석을 통해 라스트마일 배송에서 특히 배송의 유연성이 중요하다는 것을 확인하였다. 셋째, LDA(Latent Dirichlet Allocation) 분석을 통해 다섯 가지 연구 논제, 디지털화(digitalziaton), 도심 물류(urban logistics), 풀필먼트(fullfillment), 노선 최적화(route optimization), 서비스 혁신(service innovation)으로 분류하였다. 넷째, IDM(Intertopic Distance Map) 분석을 통해 디지털화와 노선 최적화, 풀필먼트와 서비스 혁신이 각각 서로 인접하여 논제의 유사성이 있음을 확인하였다. 기존의 연구가 키워드나 초록 중심으로 이루어졌으나 본 연구는 논문의 본문을 포함하여 더 많은 텍스트 정보를 제공하여 새로운 통찰력을 제공하고 기존문헌을 보완하는측면에서 학술적 기여가 있을 것으로 기대된다. With the development of online e-commerce and the COVID-19 pandemic, the demand for last-mile delivery is increasing. However, the last-mile delivery is known as a section with high inefficiency in terms of logistics cost so that it requires technological innovation or various strategies to secure profitability. Therefore, in this study, the topic modeling technique was applied to analyze the key topics of the last mile delivery related research and to provide new implications. The implications of the study results are as follows. First, through word frequency analysis, customers, time, and cost were important keywords for last mile delivery. Second, through word similarity analysis, delivery flexibility was particularly important in last-mile delivery. Third, through LDA (Latent Dirichlet Allocation) analysis, it was classified into five research topics such as digitaliziaton, fulfillment, service innovation, route optimization, and urban logistics. Fourth, through IDM (Intertopic Distance Map) analysis, digitization and route optimization were adjacent to each other, and similarly fulfillment and service innovation were adjacent to each other. This confirmed that the topics were similar respectively. Although existing studies have focused on keywords or abstracts, this study provides more textual information by including the body of the research paper so that it can provide new insights and academic contributions in terms of supplementing existing literature.

국제물류보안 인증제도 동향 및 시사점에 관한 연구

고현정(Hyunjeung Ko) 한국항만경제학회 2011 韓國港灣經濟學會誌 Vol.27 No.2

2001년 미국에서 발생한 9?11 항공기 테러사건은 국제교역의 보안에 관한 관심과 우려를 증대시켰다. 그리고 미국은 테러 위협에 대해 다층적 방어 전략을 추진하면서 행정조직을 대폭 개편하여 국토안보부를 설치하고 CSI, 화물정보 24시간 전 신고제도, SAFE Port Act, 9/11 테러대책이행법, C-TPAT 등 다양한 물류보안 제도를 마련하였다. 그 결과 전 세계적으로 물류보안 제도가 강화되고 있다. 우리나라는 동북아 물류허브화 정책추진 및 물류정책기본법에 물류보안시책을 마련하는 등 공급사슬보안에서 국가 이미지를 제고하고 국가 경쟁력을 강화하기 위한 체계적인 대응전략을 마련하고 있다. 하지만 국내 인증제도에 참여하는 실제적 당사자인 기업은 각 기관별로 운영되는 물류인증을 획득하기 위해 투자되는 시간과 비용의 중복 문제점을 지적하고 있다. 물류보안 인증제도는 국가차원의 보안강화에 따라 화물흐름의 지체현상을 필연적으로 겪게 되는 기업을 지원하자는 의도인 바, 기업의 부담을 최소화하는 통합된 국가 물류보안제도의 마련은 중요하다고 할 수 있다. 따라서 본 연구는 국제기구 및 주요국의 인증제도를 분석하고 시사점을 제시하여 국내 물류보안 인증제도의 효율적 운영방향을 설정하고자 하였다. 그리고 국가 공급사슬보안체계 구축의 기본방향을 크게 3가지, 즉 글로벌 수준의 공급사슬보안체계 구축, 국내적으로 효율적 운영체계구축, 국가적 차원의 지원체계 구축을 제시하였다. After the terrorist attack of 9/11 on the USA, the security concern to global trade has been raised. In particular, the USA has actively promoted a series of initiatives and rules such as CSI, 24 hour rule, C-TPAT, and so on in the area of logistics activities, which aimed to better protect the country against the potential terrorist threats. While implementing such schemes called as a multi-layed logistics security strategy, a large number of countries trading with USA are facing with the issues of additional time and costs for inspecting cargos in their logistics facilities. As a result, most countries all over the world have sought a way to minimize the impacts from such strategy. The Korea also is preparing the several security programs operated by various ministries, which are aiming to not only improve the efficiency of trade flows but also to ensure supply chain security. However, many companies are expressing the inefficiency of operating such programs. Thus, this paper analyzed several global supply chain security programs currently adopted by international organizations(ISO, WCO, and IMO) and major countries(USA, EU, and Singapore) and suggested a guideline for developing the national logistics security system.

환황해권 해상물류보안 협력방안에 관한 연구

고현정(Hyun-jeung Ko) 한국해양비즈니스학회 2014 해양비즈니스 Vol.- No.29

After the terrorist attack of 9/11 on the USA, the global logistics security has become an indispensable component of the international trade. In particular, Korea, China, and Japan where their total trade volume in the Pan Yellow Sea is regarded as about 20% of world trade volume are very trade dependent on each other. In addition, the ocean transit times between ports in the Pan Yellow Sea region are generally within 20 hours. This geographical feature makes the region hard to comply with the 24-Hour Rule which is one of global logistics security regulations. Thus, the purpose of this study is to explore the regional cooperation of shipping logistics security from Saemangeum point of view. Saemangeum is located in the center of the Pan Yellow Sea region, and it is a national project to build a global city as the front-runner of green growth. To this end, this paper suggested three basic principles for the regional cooperation, which were shorter transit time, costs savings, and emergency response actions. Based on such principles, this study proposed three cooperation policies. First, Saemangeum Green Lane cooperation among ports based on the predefined regional level of logistics security was suggested by which the participated ports could save not only the costs of systems investment but also the time of customs procedures. Second, the regional supply chain crime cooperation was addressed. This made the region share crime information so that the possible supply chain disruptions could be minimized. Third, the regional expert group on shipping logistics security was assembled in order to promote cooperation through the technical cooperation and capacity building, the training and eduction, and the discussion of common regional and global challenges. As a result, an efficient and secured seamless trade flow could ensured through the cooperation of the Pan Yellow region resulting in eliminating the logistics security barriers.

부가가치 극대화를 위한 새만금 신항의 발전방안에 관한 연구

고현정(Hyun-Jeung, Ko),조성우(Sung-Woo, Cho) 한국해양비즈니스학회 2012 해양비즈니스 Vol.- No.23

The aim of this study is to identify the current state of the Saemangeum New Port and understand the 'Trigger Rule' methodology that regularly examine throughput and port handling capacity, and then effectively respond the demand. We are going to suggest some ways for improvement and practical implications based on SWOT and SER-M analyses. The paper has suggested the feasible means for efficient development of Saemangeum New Port from the three perspectives. (1) customized model development of logistics business (2) long term planning (3) relationship between Gunsan Port and Saemangeum New Port(fuction sharing aspect). Finally, to establish the business model for enhancing a ripple effect is one of the critical factors in order to maintain the stable throughput and the long term development.