• 제목/요약/키워드: Six-Port

검색결과 167건 처리시간 0.022초

Analysis of Empirical Constant of Eddy Viscosity by k-ε and RNG k-ε Turbulence Model in Wake Simulation

  • Park, Il Heum;Cho, Young Jun;Lee, Jong Sup
    • 해양환경안전학회지
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    • 제25권3호
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    • pp.344-353
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    • 2019
  • The wakes behind a square cylinder were simulated using two-equation turbulence models, $k-{\varepsilon}$ and RNG $k-{\varepsilon}$ models. For comparisons between the model predictions and analytical solutions, we employed three skill assessments:, the correlation coefficient for the similarity of the wake shape, the error of maximum velocity difference (EMVD) of the accuracy of wake velocity, and the ratio of drag coefficient (RDC) for the flow patterns as in the authors' previous study. On the basis of the calculated results, we discussed the feasibility of each model for wake simulation and suggested a suitable value for an eddy viscosity related constant in each turbulence model. The $k-{\varepsilon}$ model underestimated the drag coefficient by over 40 %, and its performance was worse than that in the previous study with one-equation and mixing length models, resulting from the empirical constants in the ${\varepsilon}-equation$. In the RNG $k-{\varepsilon}$ model experiments, when an eddy viscosity related constant was six times higher than the suggested value, the model results were yielded good predictions compared with the analytical solutions. Then, the values of EMVD and RDC were 3.8 % and 3.2 %, respectively. The results of the turbulence model simulations indicated that the RNG $k-{\varepsilon}$ model results successfully represented wakes behind the square cylinder, and the mean error for all skill assessments was less than 4 %.

An Empirical Study on Trade Facilitation by the Korean Government's Single Window System

  • Cheolkyu Maeng
    • Journal of Korea Trade
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    • 제27권1호
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    • pp.101-118
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    • 2023
  • Purpose - Korea became a trillion-dollar trading country in 2011. With the exponential increase in Korea's trade volume over the past decades, trade-related administrative burdens per capita for Korea Customs became enormous, for which the government established the Single Window, a trade-facilitating system, in 2004 to enhance the efficiency of customs-clearing procedures for traders. This paper focuses on finding whether the Korean Single Window system affects the country's trade facilitation positively through an empirical methodology. Design/methodology - To find empirical evidence that Single Window affects trade facilitation for the customs-clearing procedure, this study assumes that a time-efficient environment enables the handling of the increase in trade volume, under which four independent variables related to import customs-clearing procedures and two dependent variables to import were adopted for empirical analysis. The import customs procedures are classified into four steps from port entry to declaration acceptance. To understand the relationship between variables, scattered plots and correlation coefficients were calculated. Eight hypotheses were set and underwent simple linear regression. The data for analysis were collected by Korea Customs, and were about the lead time of import, the volume of imports in million USD, and the number of import declarations reported to customs offices on a monthly basis from 2005 to 2013. Findings - Six of the eight hypotheses showed the statistically significant result that lead time in the import customs-clearing procedure positively affects the number of import declaration reports and import volume. Specifically, Hypothesis 1, Hypothesis 2, and Hypothesis 3 strongly support the assumption lead time in import customs declaration has an inverse relationship with the number of import declarations, which means that the shorter the import lead time, the more import declaration increases. Research Limitations/Implications - With limited data accessibility to the government's custom-sclearing procedures, only the import lead time for customs clearance were adopted as independent variables. This paper, however, successfully found that the Single Window system contributed to trade facilitation. Originality/value - This study found that the time-saving Single Window system of Korea Customs enables itself to manage an exponentially-increasing trade volume by creating a trade-facilitating environment for customs personnel and traders, which may be a unique implication found through quantitative methodology.

부정기선 운임변동성 영향 요인 분석에 따른 우리나라 해운정책 지원 방안 (Shipping Industry Support Plan based on Research of Factors Affecting on the Freight Rate of Bulk Carriers by Sizes)

  • 천민수;문애리;김석수
    • 한국항만경제학회지
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    • 제36권4호
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    • pp.17-30
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    • 2020
  • 해운산업에 있어 시황모니터링을 통한 선제적인 운임변동성 예측은 필수요소로서 이미 운임하락이 시작된 이후에는 선사들의 손실은 매우 커지게 된다. 이에 본 연구에서는 컨테이너운임에 비해 상대적으로 큰 운임변동성을 가지는 벌크선 운임에 영향을 미치는 요인들을 계량 분석하였으며 이를 통해 향후 해운시황모니터링에 기여하고자 한다. 이를 위해 변수들의 장기 균형관계와 단기적 동적관계를 동시에 이해할 수 있고 금융시장의 실증분석에 가장 활발히 이용되는 벡터오차수정모형을 사용한 분석을 수행하고 이를 통해 핸디사이즈, 수프라 막스, 파나막스, 케이프사이즈 선형별 벌크선 용선료에 미치는 6가지 독립변수들의 영향력을 추정하였다. 6가지 독립변수로는 벌크선 선복량, 철광석 물동량, 리보금리, 벙커유 가격, 유로-달러 환율을 선정하였으며, 종속변수는 핸디사이즈(32,000 DWT) 스팟 용선료, 수프라막스 6 T/C 평균 용선료, 파나막스(75,000 DWT) 스팟 용선료, 케이프사이즈(170,000 DWT) 스팟 용선료이다. 기존 특정 선박의 유형에 대한 연구나 벌크선 외 유조선, 케미컬 운반선에 대한 운임 연구와 차별하여 벌크선의 크기별 용선료를 대상으로 연구를 수행하였다. 분석 결과, 선박의 크기별로 영향요인이 다르게 나타났는데 리보금리는 네 가지 선박유형에 모두 유의미한 영향을 미쳤으며, 철광석 물동량은 세 가지 선박유형에 유의미한 영향을 미쳤다. 리보금리는 핸디사이즈, 수프라막스, 파나막스, 케이프사이즈에 모두 부(-)의 관계를 나타낸다, 철광석 물동량은 4가지 선형 중 파나막스를 제외하고 3가지 선형에 영향을 미치는 요인으로 작용하였다. 선사의 특성에 따라 주로 이용하는 선박사이즈가 다양하며, 해운선사의 경영성과에 지대한 영향을 미치는 용선료의 운임 변동 요인에 대해 분석함으로써 용선료 부담 완화에 따른 해운선사의 경영 전략 수립에 기여하고자 한다.

사후 서비스에서 선제적 서비스로 서비스 패러다임의 전환 (Transition of Service Paradigm from Service Recovery to Proactive Service)

  • 이현정;김향미;이창섭
    • 한국콘텐츠학회논문지
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    • 제20권4호
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    • pp.396-405
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    • 2020
  • 본 연구에서는 초고속인터넷 상품에 관련된 고객 불만사항(VOC, Voice of Customer)의 빅데이터를 활용하여 고객이 지각하는 품질이상의 원인과 선제적 서비스의 가능성을 살펴보았다. 선제적 서비스의 가능성을 검증하기 위해 실제 이동통신 서비스기업의 시설·장비의 총 13개 장애경보에 관련된 품질이상 VOC를 수집한 후, 𝒙2검증을 통해 품질이상 VOC 실제관측값과 기대값이 통계적으로 유의한 차이가 있는 지 검증하였다. 연구결과, 시설·장비의 총 13개 장애경보 관련 품질이상 VOC 중 6개의 장애경보로서, 'FTTH-R 장비 ON/OFF', 'FTTH-E,V 회선오류 감지', '포트불량, FTTH-R 회선오류 감지', '네트워크 LOOP 감지', 그리고 '비정상 트래픽 제한'은 실시간 모니터링을 통한 선제적 서비스가 가능하다는 통계적 근거를 찾았다. 기업들은 이러한 선제적 서비스를 이용하여 시잠점유율을 향상키시고 고객서비스 비용을 절감하는 데 적용할 수 있을 것이다. 본 연구의 결과는 통신서비스 분야의 선제적 서비스의 가능성을 진단하고, 나아가 효과적인 선제적 서비스 제공 방안에 대한 시사점을 제시하였다는 점에서 실제 산업 적용에 대한 공헌점이 기대된다.

상표자산이 구매의도에 미치는 영향: 중국패션시장에서 (Brand Equity and Purchase Intention: The Fashion Market in China)

  • 이동해;최영로
    • 유통과학연구
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    • 제13권7호
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    • pp.85-90
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    • 2015
  • Purpose - Global trends play a part to change the structure of the fashion industry. In particular, companies attempting to conduct innovative marketing centering on such products as SPA brands are growing into global companies. SPA stands for "Specialty Store Retailer of Private Label Apparel", meaning its activities are fully integrated from manufacturing through sales, including material procurement design, product, distribution, inventory management, and final sales. For this reason, more understanding of individual corporate profitability is very sensitive to consumer's attitudinal changes. The effects that corporate marketing activities on customer lifetime value through brand attitude were analyzed based on a structural equation model. Rust suggested value equity, brand equity, and relationship equity as customer equity driver. The study examines Chinese consumer because China is the fastest growing fashion market in the world. Research design, data, and methodology - The survey targeted Chinese college student age 20s. Only respondents who had purchased SPA brands in the past year were included for this research. A total of 303, except for 47 missing data of 350 distributed questionnaires were included in this research. The questionnaire is consists of six part to measure value, brand, relationship equity, attitude toward brand, purchase intention and demographic characteristics. This research conducted exploratory factor analysis and reliability test. To verify research hypotheses, structural equation model test was conducted. As for customer equity, diversified models in consideration of the scope of acquisition data, a method of collection of data, influencing factor, and predictability were suggested based on a net present value model. However, the history of customer equity study is relatively short, and sufficient empirical analyses have not been conducted, so more integrated analysis is required. In this study, the concept of driver suggested by Rust was applied to figure out the effects that consumer's attitude has on customer equity. The customer equity driver suggested by them consists of brand equity, value equity, and relationship equity. Results - This study reveals that value equity and brand equity have a positive influence on relationship equity. And, relationship equity has a positive influence on purchase intention through brand attitude. However, value equity and brand equity do not influence on brand attitude. Conclusion - The results of this research generated following implications. First, SPA brands need to take advantage of their value equity such as perceived low price and up-to-date fashion style to attract Chinese young consumer. Second, strong brand equity promises dominants position in the competitive market. As Chinese fashion market grows rapidly, SPA brands can consider branding strategy such as flagship store and celebrity marketing enhancing brand image. Third, the core concept of customer equity strategy is to maintain a relationship with their expecting and existing customers. The relationship equity is built by brand equity and value equity. When SPA brands serves product and service meet with individual customers, customers have intimacy to the brands.

멕시코 마낄라도라산업의 특성과 분포 변화 (The Changes in the Characteristics and Distribution of Maquiladora Industries in Mexico)

  • 김희순
    • 한국경제지리학회지
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    • 제11권2호
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    • pp.251-271
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    • 2008
  • 멕시코의 마낄라도라산업은 1980년대 및 1990년대 멕시코의 경제위기로 인한 노동비의 감소, NAFTA 발효로 인한 멕시코의 북미시장으로의 진출 가능성의 제고 등으로 인해 성장하였다. 초기 마낄라도라산업은 멕시코의 북부 접경지역에서 젊은 여성 노동력을 바탕으로 섬유 및 전자 조립 부분을 중심으로 입지하기 시작하였으나 1980년대 이후 생산액 및 고용면에서 기계 및 전자 부문의 비중이 증가되었고 남성의 노동력 참여율도 높아졌으며 분포 지역 또한 25개 주로 확대되었다. 멕시코의 마낄라도라 산업에서 가장 주요한 지역은 치와와와 바하 칼리포르니아 주이며 주요 도시는 씨우다드 후아레스와 티후아나이다. 마낄라도라산업은 1990년대 후반 생산액과 고용면에서 비약적인 증가를 하여 2000년을 전후하여 전성기를 맞았으나, 이후 생산액 측면에서는 약간의 감소가, 고용측면에서는 비교적 큰 감소가 나타났다. 마낄라도라산업의 입지 가능 범위는 멕시코 모든 지역으로 확대되었지만 아직도 대부분의 마낄라도라산업은 북부 접경 6개주를 중심으로 입지하고 있다. 섬유산업의 경우 마낄라도라산업의 대표적인 산업으로서 마낄라도라산업 성장의 초기에 해당하는 지역의 대부분이 섬유산업 중심이다. 따라서 섬유산업은 마낄라도라 산업 전반과 분포패턴이 유사하게 나타났다. 그러나 기계 및 전자 산업의 경우 북부 접경주로의 집중이 매우 두드러지며 기존 공업지대가 입지한 지역에 분포하는 특성이 나타났다. 산업별 고용 변화를 살펴본 결과 기계 및 전자 부문의 고용이 가장 많았고 섬유 부문이 그 뒤를 따랐다. 기타 부문 중 특기할 점은 서비스업의 꾸준한 증가이다.

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공공보건조직에서의 방문간호사업모형개발 : 보건진료소 방문간호사업 (Development of a Home Health Care Model in the Public Health System -Visiting Health Service by Community Health Practitioners)

  • 한경자;박성애;하양숙;윤순녕;송미순
    • 대한간호학회지
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    • 제25권3호
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    • pp.472-484
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    • 1995
  • The purpose of this study was to develop a home health care model in the public health system and to test the effectiveness of the model. Seven com-munity health practitioners in Yon- Cheon county. Kyunggi province, carried out home health care service for this research. The subjects of the home health care were a total of 111 community residents with chronic health problems and risk-prone infants and children; 29 persons with hypertension, 18 persons with diabetes, 12 persons with neurologic problems, 12 elderly, and 40 infants and children. During the period of study, from December, 1993 to March, 1995, a demonstrative home health care model was developed in the Yon-Cheon County community health centers with the cooperation of the Yon-Cheon Medical Center and Yon-Cheon Public Health Center for the first six months. A home care practice manual and recording system for home visits were also co-developed by the researchers and community health practitioners. Four workshops and monthly conferences were held for this purpose. Actual home care practice took place for two months, and on-going evaluation and replanning accompanied this process. The result of the evaluation of home care service were as follows. 1) For persons with hypertension, diabetes, neurologic problems, there was significant improvement in knowledge of disease and care, but no significant difference was seen in health behavior or symptoms after home care service. 2) No significant difference was seen in level of self esteem or depression after reminiscence therapy among 12 elderly subjects. 3) There were significant differences in satis-faction toward child rearing and parental sup-port, but no significant difference In education needs for parental role after home care service among parents of infants and children. 4) There was significant improvement in the quality of life among the subjects after the home care service. 5) Subjects responded that they were highly satisfied with the home care service given by the community health practitioners. Although, the actual implementation period was very short, and not all of the evaluation outcomes showed significant improvement, the home health care model of community health practitioners was, in general, positively evaluated. Through this re-search, the possibility of community health practitioners working as active home care personnel in the public health care system is supported. Further research with an expanded area and subjects for a longer period is recommended. Cost effectiveness research is also needed.

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Removal of residual VOCs in a collection chamber using decompression for analysis of large volatile sample

  • Lee, In-Ho;Byun, Chang Kyu;Eum, Chul Hun;Kim, Taewook;Lee, Sam-Keun
    • 분석과학
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    • 제34권1호
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    • pp.23-35
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    • 2021
  • In order to measure the volatile organic compounds (VOCs) of a sample which is too large to use commercially available chamber, a stainless steel vacuum chamber (VC) (with an internal diameter of 205 mm and a height of 50 mm) was manufactured and the temperature of the chamber was controlled using an oven. After concentrating the volatiles of the sample in the chamber by helium gas, it was made possible to remove residual volatile substances present in the chamber under reduced pressure ((2 ± 1) × 10-2 mmHg). The chamber was connected to a purge & trap (P&T) using a 6 port valve to concentrate the VOCs, which were analyzed by gas chromatography-mass spectrometry (GC-MS) after thermal desorption (VC-P&T-GC-MS). Using toluene, the toluene recovery rate of this device was 85 ± 2 %, reproducibility was 5 ± 2 %, and the detection limit was 0.01 ng L-1. The method of removing VOCs remaining in the chamber with helium and the method of removing those with reduced pressure was compared using Korean drinking water regulation (KDWR) VOC Mix A (5 μL of 100 ㎍ mL-1) and butylated hydroxytoluene (BHT, 2 μL of 500 ㎍ mL-1). In case of using helium, which requires a large amount of gas and time, reduced pressure ((2 ± 1) × 10-2 mmHg) only during the GC-MS running time, could remove VOCs and BHT to less than 0.1 % of the original injection concentration. As a result of analyzing volatile substances using VC-P&T-GC-MS of six types of cell phone case, BHT was detected in four types and quantitatively analyzed. Maintaining the chamber at reduced pressure during the GC-MS analysis time eliminated memory effect and did not affect the next sample analysis. The volatile substances in a cell phone case were also analyzed by dynamic headspace (HT3) and GC-MS, and the results of the analysis were compared with those of VC-P&T-GC-MS. Considering the chamber volume and sample weight, the VC-P&T configuration was able to collect volatile substances more efficiently than the HT3. The VC-P&T-GC-MS system is believed to be useful for VOCs measurement of inhomogeneous large sample or devices used inside clean rooms.

한국 연안에 출현하는 Aidanosagitta crassa 형태 유형에 따른 분류학적 고찰 및 계절별 출현 특성 (Seasonal occurrence characteristics of Aidanosagitta crassa morphotypes in coastal waters of Korea)

  • 추서휘;정만기;서민호;정영석;박종준;신아영;서호영
    • 환경생물
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    • 제42권3호
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    • pp.267-278
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    • 2024
  • 한국 연안 해역의 핵심 종인 Aidanosagitta crassa는 세 가지 형태적 유형을 보인다. 지느러미의 포상조직이 머리부터 꼬리까지 분포하고 있는 C형, 포상조직이 몸 일부에만 분포하는 N형, 그리고 C형과 N형의 중간 형태인 I형이다. 유형에 따른 A. crassa의 출현 특성에 대한 생태적인 연구가 부족하기 때문에 이 연구에서는 A. crassa 유형의 계절적 발생 패턴을 밝히고자 했다. 평택항의 여섯 정점에서 현장 조사는 2010년 겨울(2월), 봄(5월), 여름(8월), 가을(11월)에 실시하였다. 수온과 염분을 측정하였으며, 동물플랑크톤을 수집하였다. A. crassa C형은 겨울과 가을에, I형은 여름에, N형은 여름과 가을에 우점하는 경향을 보였다. 이들의 출현은 수온에 큰 영향을 받은 것으로 확인되었다. 각 유형별로 C형은 음의 상관관계를 보였고, N형은 양의 상관관계를 보였으며, I형은 유의한 상관관계를 보이지 않았다. 2013년에는 mtCOI 마커를 이용한 분자생물학적 분석이 겨울과 여름에 실시되었다. 형태학적 차이에도 불구하고, 유형 간의 유전적 분석 결과는 계절적 환경 변화로 인한 종내 다양성임을 보였다.

Feasibility and safety of endoscopic submucosal dissection for lesions in proximity to a colonic diverticulum

  • Nobuaki Ikezawa;Takashi Toyonaga;Shinwa Tanaka;Tetsuya Yoshizaki;Toshitatsu Takao;Hirofumi Abe;Hiroya Sakaguchi;Kazunori Tsuda;Satoshi Urakami;Tatsuya Nakai;Taku Harada;Kou Miura;Takahisa Yamasaki;Stuart Kostalas;Yoshinori Morita;Yuzo Kodama
    • Clinical Endoscopy
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    • 제55권3호
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    • pp.417-425
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    • 2022
  • Background/Aims: Endoscopic submucosal dissection (ESD) for diverticulum-associated colorectal lesions is generally contraindicated because of the high risk of perforation. Several studies on patients with such lesions treated with ESD have been reported recently. However, the feasibility and safety of ESD for lesions in proximity to a colonic diverticulum (D-ESD) have not been fully clarified. The aim of this study was to evaluate the feasibility and safety of D-ESD. Methods: D-ESD was defined as ESD for lesions within approximately 3 mm of a diverticulum. Twenty-six consecutive patients who underwent D-ESD were included. Two strategic approaches were used depending on whether submucosal dissection of the diverticulum-related part was required (strategy B) or not (strategy A). Treatment outcomes and adverse events associated with each strategy were analyzed. Results: The en bloc resection rate was 96.2%. The R0 and curative resection rates were 76.4% and 70.6% in strategy A and 88.9% and 77.8% in strategy B, respectively. Two cases of intraoperative perforation and one case of delayed perforation occurred. The delayed perforation case required emergency surgery, but the other cases were managed conservatively. Conclusions: D-ESD may be a feasible treatment option. However, it should be performed in a high-volume center by expert hands because it requires highly skilled endoscopic techniques.