• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.144-146
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• 1999

This paper provides an analysis of the effect of input signals, such as acceleration power and generator shaft speed for improving Power System Stabilizer(PSS) efficiency. We consider a single machine and infinite bus system which is modeled by PSCAD/EMTDC. We choose an optimum stabilizer gain with respect to eigenvalue analysis and transient stability analysis to each input signal.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.975-980
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• 2002

We actually installed antibacterial air filter on the air intake route to air conditioner in passenger car and evaluated filters performance on antibacterial effect. And also, antibacterial effect was observed at whole are of filter media by zone of inhibition test. In the evaluation of antibacterial test, it was shown that the air filter has notably sufficient antibacterial efficiency against ordinary filter.

• International Journal of High-Rise Buildings
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• v.3 no.3
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• pp.185-190
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• 2014

Based on a 405m high super-tall building, the influence of outriggers, different shapes and layouts of structural plane and elevation on structural efficiency under lateral forces is studied in this paper. A calculation formula concerning the structural efficiency is given. The study shows that structural efficiency can be improved by triangulating the plane shape, using mega columns, the peripherization of the plane layout, tapering the elevation shape and setting bracing structure in the elevation. The arrangement of outriggers between the core tube and flange frame can reduce the shear lag effect in order to improve structural efficiency. The essence of improving structural efficiency of super-tall buildings is to maximize the plane bending stiffness and to make its deformation approach to plane section assumption.

• Proceedings of the Korea Database Society Conference
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• 2008.05a
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• pp.321-338
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• 2008

Information and communication industry, which shows rapid growth rate, is now leading the global economic growth, contributing a ripple effect on general business and economic structure. It is said that information and communication industry enables swift economic growth taking a role as a basic industry of information-oriented society. Especially, rapid technical innovation promotes mutual growth of other related industries and it is technology-intensive. The purpose of this research is to analyze the management efficiency of information and communication industry using DEA method, and finally suggest numerical value for inefficient organizations to improve their efficiency. CCR-I, BCC-I efficiency and RTS(Returns to scale) of 29 companies engaged in information and communication industry was evaluated. With the results, I suggested model companies for benchmarking in information and communication industry. To summarize, 7 companies were selected with CCR-I efficiency rate 1, and 12 companies with BCC-I efficiency rate 1. RTS was finalized with 8 IRS companies, 10 DRS companies, and 11 CRS companies.

• Journal of the Korea Safety Management & Science
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• v.9 no.5
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• pp.125-133
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• 2007

Everyone knows how much the company business goal is achieved is the most important to all companies. In order to maximize the business performance, many companies have introduced a diversity of management innovation activities. The effect of business performance is important in the business activity, but an efficiency of output-to-input concept is significantly important. Each year, companies have managed the business through a sum of performance. In terms of the efficiency of business performance, the management is importantly managed. In the efficiency of business performance, there are the main items including the total assets, employees, and operating expenses as the input. As the output, there are the main items of sales, current term's net income. This study is intended to calculate the business efficiency through DEA analysis for companies' business performance, and to study in order for the efficiency of business performance to be considered when the companies establish the mid and long term business plan.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.125-136
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• 2016

The external R&D, which includes the adoption of the external technology and knowledge in addition to the internal R&D, is one of important factors for the innovation. Especially for small and medium-sized enterprises (SMEs), the external R&D has been considered as a key factor to carry out the innovation more efficiently due to the limitations of their resources and capacities. However, most of extant studies related to external R&D have focused on analyzing the influence of external R&D on innovation outputs or outcomes. Only a few studies have explored the impact of external R&D on the innovation efficiency. This study therefore investigates whether the external R&D effects the industry's innovation efficiency and productivity. On this study, we used Korean manufacturing industry data of SMEs from 2012 to 2014 and employed a global Malmquist productivity analysis technique, which is based on the Data Envelopment Analysis (DEA), to assess the innovation efficiency and productivity. Innovation performances of external R&D group and internal R&D group are compared. Then, the sectoral patterns of both innovation efficiency and productivity are analyzed with respect to the technological intensity, which is introduced by OECD. The results show that the gap of innovation efficiency between external and internal R&D groups has gradually decreased because of the continuous improvement of the external R&D group's performance, while the external R&D group lag behind the internal R&D group. In addition, patterns of the innovation efficiency and productivity change were different depending on the technological intensity, which means that the higher the technological intensity, the greater the effect of external R&D.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1030-1036
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• 2009

In 1990's, in Europe and some advanced nations, the structural reform of the railroad industry for improving the productive efficiency of the railroad industry and competitive power had been progressed. This paper empirically explores the relationship between railway restructuring and productive efficiency in the railway industry. We use Data Envelopment Analysis (DEA) to construct efficiency scores, and explain these scores, using Tobit regression analysis by using variables reflecting institutional factors and organizational type. Our results suggest that vertical separation, infrastructure and services are separated, and horizontal separation, passenger service and freight service are separated, improve productive efficiency. We also find that market competition has positive effect on the efficiency, but independent management from the government has negative effect, which is in line with economic intuition as well as with expectations on the railway restructuring. As a consequence, increased independence without sufficient competition and adequate regulation may deteriorate incentives for productive efficiency.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.371-381
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• 2014

Recently the water quality management policy gives priority to management the point source. Non-point pollution source is difficult to comprehend because those don't have certain outflow point and emission. There are many development and research about BMPs for manage the Non-point pollution source. Various methods of removal efficiency are presented for assessment of Best Management Practices (BMPs). In this study, retention time have effect on removal efficiency based on monitoring results of Grassed Swale is studied. Also, Compare a difference according to various methods of Grassed Swale removal efficiency. The result of removal efficiency analysis depending on retention time of Grassed Swale, removal efficiency is higher as retention time increases. To obtain a stable removal efficiency of Grassed Swale, retention time of Grassed Swale should be secure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.9
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• pp.468-474
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• 2015

When oil is used for cooking in detached or apartment houses, large amounts of oil-mist, smoke, and particulate substances are generated and dispersed into the indoor-air environment. These pollutants diffuse into the surroundings and spread their odor while rising fast at a high temperature due to the heat energy from the gas range. Although the exhaust gas is discharged from the exhaust hood, which is installed on the top of a gas range to remove the diffuse pollutants, the exhaust conditions can vary greatly because they depend on the shape of the exhaust hood and the discharge rate. In this paper, the air that is required for the gas-exhaustion process is supplied by an air curtain that surrounds the kitchen hood, and the pollutant-capturing efficiency varies depending on the angle of the discharge grills; the pollutant-capturing efficiency was studied using a numerical-analysis method. The results indicate that the pollutant-capturing efficiency is not significantly changed by a change of the discharge-grill angle at a low air-discharge rate; however, at a high air-discharge rate, the efficiency value increases with an increase of the discharge-grill angle, whereby the best value occurs at 30 degrees and the efficiency decreases above this angle. Below 30 degrees, the effect of the discharge rate on the capturing efficiency is more than that of the discharge-grill angle.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.93-102
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• 2016

The purpose of this study is to examine the effects of the Mobile Smart-Work IT resources on the work efficiency based on moderating effects of the perceived usefulness in the Resource Based View. The study has academic meanings and practical implications that studied widely based on moderating effects of the perceived usefulness through the Hierarchical regression furthermore on the existing study on hypothesis by standard multiple regression. The results showed that IT Infrastructure in the Mobile Smart-work IT resources by moderating effects of the perceived usefulness was found to bring positive effect on individual work efficiency and teamwork efficiency. On the other hand Business Application was found to bring positive effect on teamwork efficiency. Therefore, we expect that business firm and employees actively use the effects of the perceived usefulness with the trust that Mobile Smart-work IT resources bring positive effects on the work efficiency. It can improve this work efficiency and lead to strengthening the firm competitiveness.