• 동력기계공학회지
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• 제11권3호
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• pp.22-28
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• 2007

Liquefied gas vaporizer is a machine to vaporize liquefied gas such as liquid nitrogen($LN_{2}$), liquefied natural gas(LNG), liquid oxygen($LO_{2}$) etc. For the air type vaporizer, the frozen dew is created by temperature drop (below 273 K) on vaporizer surface. The layer of ice make a contractions on vaporizer. The structure analysis on the heat transfer was studied to see the effect of geometric parameters of the vaporizer, which are length 1000 mm of various type vaporizer. Structure analysis result such as temperature variation, thermal stress and thermal strain have high efficiency of heat emission as increase of thermal conductivity. As the result, Frist, With-fin model shows high temperature distribution better than without-fin on the temperature analysis. Second, Without-fin model shows double contractions better then with-fin model under the super low temperature load on the thermal strain analysis. Third, Vaporizer fin can be apply not only heat exchange but also a stiffener of structure. Finally, we confirm that All model vaporizer can be stand for sudden load change because of compressive yield stress shows within 280 MPa on thermal stress analysis.

• 전기학회논문지
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• 제65권3호
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• pp.411-418
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• 2016

In accordance with global energy conservation policies such as MEPS(Minimum Energy Performance Standard), electric motor industry is moving to super-high-efficiency machines and research to develop IE4 (International Energy Efficiency Class4) motors has been launched. In this situation, SynRM (Synchronous Reluctance Motor) has been attracting attention in place of induction motor which hardly provides super premium efficiency. As a result, much research on SynRM is being performed at home and abroad. Also, some products have already been appearing in the market. Compared to induction motor, SynRM has better efficiency per unit area and wider operating range. Although the utilization of control system in synchronous motor results in higher prices, we still need to concentrate on developments of SynRM so as to comply with the new policies. This study demonstrated the electromagnetic design methods of super-premium SynRM while maintaining the frame of existing IE3 induction motor for blower. We documented the design procedures for generating high saliency which is the most essential and mechanical stress analysis is also treated. In conclusion, we proved the validity of our design by manufacturing and testing our SynRM models.

• 산업경영시스템학회지
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• 제40권4호
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• pp.21-28
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• 2017

Improving efficiency of the telecommunication is crucial to the development and growth of Korean economy. Recently, it has become important with the huge development of information technology and its greater potential for extensive impact on the rest of the economy. Hence, it is useful to determine the factors that help enhance efficiency in telecommunication and consider them in improving the evaluation model. This study applies DEA (data envelopment analysis) to evaluate the relative efficiency of 51 branches of a Korean telecommunication company. Using the super-efficiency approach, we tested outliers which may affect the results and ranked the efficient branches. A method of deriving key variables applied to business operation is proposed to identify the key performance indicators for evaluation that takes environmental (non-discretionary) factors into account. We used the extended CCR model proposed by Banker and Morey to investigate the influence of non-discretionary factor. The information provided by the model (slacks, weights) and the sensitivity analysis shows that the most important indicator that affects the branch performance is operating cost. The results of sensitivity analysis show that average efficient score decreases from 0.972 (base case) to 0.863 for CASE2-COST. The average score of the data proves the priority of operating cost over other indicators. The effect of environmental (non-discretionary) variable was found to be significant. The population effect was positive and improved overall efficiency by 0.91% on average. Non-discretionary factor plays a meaningful role explaining the performance of branches. The performance optimization report can help a manager of an inefficient branch to develop branch strategies. Managers can identify the top-performing units, study best practices and adopt the strategy to the organization.

• KIEAE Journal
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• 제10권5호
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• pp.63-69
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• 2010

Recently, by the increase of demand on Super High-rise mixed-use housing and it's advanced quality, the interest on it has been raised socially. In accordance with it, the matter of resident's health and energy efficiency has been controversial in terms of living in super high-rise housing. This study started from the idea that it is necessary to have an objective data which that has many residents in narrow space with high density. The purpose of this study are as follows; Firstly, with the quantitative data analysis on energy, it will confirm the objective information on the unclear negative idea of super high-rise mixed-use housing. Secondly, it will establish the fundamental data on the energy of super high-rise mixed-use housing by examining the characteristic of energy consumption of the complex which was built more than 5 years ago. There are 4 methods of this study. Firstly, it follows the steps of theoretical view, and defines concept to study on the characteristic of super high-rise mixed-use housing. Secondly, referring to the previous study, it provides better understanding on th stream of this research and the limit as well to guide the direction in terms of energy consumption. Thirdly, it evaluates the characteristic of monthly consumption by researching the use of electricity energy and heating energy of super high-rise mixed-use housing. The major conclusions of this study are as follows; Firstly, the heating use of apartment complex is same, which is not influenced by the type of the building. Secondly, the electricity use of super high-rise mixed-use housing is from 1,2 to 1.5 as high as the normal apartment.

• 유통과학연구
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• 제12권4호
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• pp.23-30
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• 2014

Purpose - The purpose of this study is to analyze the efficiency of retail businesses by dividing domestic retailers into discount stores, super supermarkets (SSMs), and department stores. It suggests retail-business investment strategies by using data environment analysis (DEA) to analyze how input elements such as store area, parking lot area, number of employees, and sales management expenses for the convenience of customers positively affect business performance measurements such as sales and visiting customers per day. Research Design, Data, and Methodology - The DEA model calculates a ratio of the weighted mean of various inputs to the weighted mean of various outputs and measures the efficiency of a specific decision making unit (DMU). The study included 19 companies (five discount store DMUs, ten SSM DMUs, and four department store DMUs). Because the business elements and sizes of retail store DMUs used in this analysis are different, average per-store input and output variables were used. Data were collected from "The Yearbook of Retail Industry in Korea (2012)." DEA analysis was used to determine differences in efficiency among discount stores, SSMs, and department stores in terms of the business elements of each retail business. It was also used to determine what business elements were excessively invested in by comparing and analyzing efficiency by business elements using SPSS software's ANOVA (Analysis of Variance). Results - The CCR and BCC efficiency analysis found that the efficiency of discount stores is low. We believe that the saturation state of discount stores is a major factor. The ANOVA analysis confirms the VRS hypothesis with a statistically significant difference among the three groups, based on an analysis confidence interval of 95%. CRS and SE were not found to be significantly different among the three groups. As for the post hoc test, which concretely shows differences by group, the Scheffe's multiple comparison analysis test found the average differences between group 1 (discount stores) and group 2 (SSM) to be statistically significant. Conclusions - The DEA efficiency analysis implies that investment in input elements, including store area, parking lot area, and sales management expenses, were excessive in the case of discount stores, while SSMs need to invest more in promotion activities such as gifts, events, and coupons for customer management. Department stores have found that small companies invest excessively in input elements. Department stores need to invest in differentiated shopping mall complexes. This study was limited in acquiring statistical data; various input variables which might have shown more secure customer management and promotional expenses could not be applied. As the study was limited in various aspects of the efficiency analyses because financial analyses of the companies and of causal relationships, including satisfaction and loyalty of visiting customers, were not done, these aspects will be examined in the next study.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1069-1074
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• 2006

Heat loss by window in building occupies about 1/4 of energy amount used building. Therefore, high thermal insulation of windows system can speak as very important part in save energy of building. in this research, After select most suitable frame design and Glazing system for high thermal insulation of windows, execute simulation of mixing frame and Glazing System. Also, manufacture windows with the result and execute verification experiment, with verified simulation, this research evaluated thermal insulation performance of window by Glazing System's change.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.635-655
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• 2020

The sag effect of long stay cables is one of the key factors restricting further increase in the span of cable-stayed bridges. Based on the formerly proposed concept of long stay cables lifted by an auxiliary suspension cable in cross-strait cable-stayed bridges, corresponding static approximate calculations and analytical theory based on catenary and parabolic cable configurations are established. Taking a main span 1400 m cable-stayed bridge as the research object, three typical lifting conditions and the whole process of auxiliary cable lifting are analyzed and discussed. The results show that the sag effect is effectively reduced. The support efficiency is only improved when the cables are lifted above the original cable chord. Reduction of the horizontal component force of the cable is limited. The equivalent elastic modulus and the vertical support stiffness of the lifted cables are significantly increased with increased horizontal projection length and not sensitive to the change of the lifting point position. The scheme of lifting the cable to the chord midpoint is more economical because of the less steel required for the auxiliary suspension cable, but its effect on improving the vertical support efficiency is limited. The support efficiency is better when the cable is lifted to the cable end tangential to the original cable chord, but the lifting force and the cross-sectional area of the auxiliary suspension cable are doubled. The approximate calculation results of the lifted cables are very close to the numerical analysis results, which verifies the applicability of the approximation method proposed in this study. The results of parabolic approximation calculations are approximately equal to that of catenary cable geometry. As the parabolic approximation analysis theory of lifted cables is more convenient in mathematical processing, it is feasible to use parabolic approximation analysis theory as the analytical method for the conceptual design of lifted cables of super-long span cable-stayed bridges.

• 서비스연구
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• 제11권4호
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• pp.43-55
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• 2021

본 연구는 OECD 회원국들을 대상으로 의료서비스의 운영효율성과 품질효율성을 비교 분석하였다. 이를 위하여 2017~2019년의 OECD 보건통계(Health Statistics) 자료를 이용하였다. 분석 방법으로는 산출지향형(output-oriented) 규모수익가변(VRS: Variable Returns to Scale) 모형을 적용하여 초효율성(super efficiency)을 측정하였다. 분석결과, 운영효율성의 상위 그룹에는 스위스, 한국, 이탈리아, 노르웨이, 오스트리아, 네덜란드, 중위 그룹에는 캐나다, 그리스, 덴마크, 멕시코, 미국, 영국, 체코, 프랑스, 핀란드, 헝가리, 호주, 하위 그룹에는 벨기에, 독일, 스페인이 포함되었다. 품질효율성의 상위 그룹에는 노르웨이, 스위스, 스페인, 중위 그룹에는 그리스, 덴마크, 멕시코, 미국, 영국, 캐나다, 프랑스, 핀란드, 헝가리, 호주, 하위 그룹에는 네덜란드, 독일, 벨기에, 오스트리아, 이탈리아, 체코, 한국이 해당되었다. 2018년을 기준으로 OECD 회원국별로 효율성을 비교 분석한 결과, 운영효율성이 가장 효율적인 한국은 품질효율성이 비효율적이었다. 한국(0.998)은 그리스(0.422), 스위스(0.207), 스페인(0.371)을 벤치마킹하여 기대수명을 0.2(0.2%), 주관적 건강 인지를 44.2(138.1%)씩 개선하여 품질효율성을 향상시켜야 한다. 이는 국내에서 기대수명이나 유병률 같은 객관적 지표로 건강상태를 측정하고 있지만, 의학적 진단 여부와 별개로 국민들이 본인의 건강에 관하여 주관적으로 평가하는 것을 관리할 필요가 있음을 의미한다. 본 연구는 운영효율성에 초점을 맞춘 대부분의 선행연구들과 다르게 운영효율성과 품질효율성을 함께 측정했다는 점에서 학술적인 시사점을 지닌다. 또한 OECD 회원국별 의료서비스 산업의 효율성을 비교 분석함으로써, 국내 의료서비스 산업의 국제적인 경쟁력 수준을 확인하고 효율성 개선 방안을 제시했다는 점에서 실무적인 시사점을 지닌다.

• Environmental Engineering Research
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• 제25권1호
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• pp.71-79
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• 2020

This paper uses super-efficiency DEA model and Malmquist index to evaluate the carbon emission efficiency (CEE) values of the nine western provinces along the "Silk Road Economic Belt" for the period from 2000 to 2015, and analyses the influencing factors of the CEE. The major findings of this study are the following: (1) the overall CEE of the nine western provinces is not high, and there are significant inter-provincial differences in the CEE. Meanwhile, the provinces with higher levels of economic development generally have higher CEE. (2) The annual total factor productivity (TFP) of the nine western provinces, which is mainly determined by technological change, is greater than 1. Moreover, the total average growth rate of the TFP is 15.5%. (3) The CEE of the nine western provinces is not spatially dependent. In addition, the urbanization, openness, use of energy-saving technologies and research and development (R&D) investment have a significant positive impact on the CEE values, while the industrial structure, foreign direct investment, fixed asset investment, government expenditure levels and energy structure have a significant negative impact on the CEE. Among them, R&D investment is the primary factor in promoting the development of CEE, and the government expenditure has the greatest negative impact on the CEE.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.30-37
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• 2012

This paper presents the performance investigation and design technology of a Line Start-up Permanent Magnet Synchronous Motor (LSPMSM) with super premium efficiency, including a design consideration and evaluation for motor start-up, key performance, and advanced finite element analysis FEA) for the design, improvement and verification, prototype build and test, design and test data comparison with a $Premium^{(R)}$ Efficient Induction Motor (PEIM). To assess the design technology, the LSPMSM prototype was built amended from a PEIM with the same frame, stator punching and rated output. Based on the prototype test, two novel design improvements and analyses have been done to eliminate noise and vibration. Additionally, the comparisons with the PEIM on the power factor, efficiency, frame size and active material consumption indicated that a significant performance improvement and active material cost reduction can be achieved by the LSPMSM.