• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.9
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• pp.448-453
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• 2003

In this paper the controlled closing algorithm of the circuit breaker for isolated capacitor banks is proposed. The characteristics of circuit breakers such as RDDS(rate of decrease of dielectric strength) and a mechanical operating tolerance should be also taken into account to locate contact touch instants around voltage zero. The analysis results on the voltages across circuit breaker terminals upon closing operation play an important roles to describe the suggested method. The simulations carried out in order to verify the performance of this method show that the closing instants obtained from the proposed method provide a good suppression effect on the closing transients for both single and back-to-back capacitor banks.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1368-1370
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• 1996

The Information of Edges which takes small area comparing with the total image is very important in DNA images as well as general images. DNA image is the object should be managed by computing and it's demanding information is less than general images, but the accuracy is more important In a huge DNA image processing system such as DNA Information Bank, the performance depends on the size of image. In this paper, we extract the edge information and make it as a binary image. To reduce the size of the original image, it was applied by JPEG image compression method. The compressed image is combined with edge information when they are restored. As a result, Both the image compression ratio and restoration quality are optimized without the loss of critical information.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.256-257
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• 2012

This paper presents a new control strategy to improve voltage performance of distributed generation (DG) under nonlinear loads. The proposed voltage controller consists of a proportional-integral and a repetitive controller where the repetitive controller behaves as a bank of resonant controllers to compensate harmonic voltage drop on system impedance due to nonlinear load current. As a result, the voltage at the point of common coupling (PCC) of the DG is regulated to be sinusoidal waveform regardless of the presence of nonlinear loads. In order to validate the effectiveness of the proposed voltage controller, simulations are carried out using PSIM software and results are compared with those with the conventional PI controller.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.270-279
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• 2003

Parametric studies have been conducted into the variability of the factors affecting the ultrasonic testing applied to weldments. The influence of ultrasonic equipment, transducer parameters, test technique, job parameters, defect type and characteristics on reliability far defect detection and sizing was investigated by experimentation. The investigation was able to build up substantial bank of information on the reliability of manual ultrasonic method for testing weldments. The major findings of the study separate into two parts, one dealing with correlation between ultrasonic techniques, equipment and defect parameters and inspection performance effectiveness and other with human factors. Defect detection abilities are dependent on the training, experience and proficiency of the UT operators, the equipment used, the effectiveness of procedures and techniques.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.483-490
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• 2006

본 연구에서는 조직 구성원의 협업을 위하여 도입되는 그룹지원시스템(group support system; GSS)를 대상으로 GSS의 사용에 미치는 영향과 GSS의 사용으로 인한 개인의 성과의 관계에 대한 연구를 실시하였다. 본 연구를 위해 개인의 기술수용 요인에 대한 연구에서 보편적으로 널리 사용되어 온 기술수용모델(technology acceptance model; TAM)과 사용자의 과업과의 연관성을 고려한 과학기술적합(task-technology fit; TTF) 개념, 그리고 적응구조화이론(adaptive structuration theory; AST)을 통합하여 그룹 구성원들이 GSS의 도입의도에 맞게 사용하는 것이 개인과 조직의 성과를 향상시키는지 검증하였다. 연구결과, 높은 TTF는 사용자들이 GSS에 대하여 지각하는 유용성과 용이성에 영향을 미친다는 것을 검증하였다. 또한, TTF가 사용자들의 적절한 사용을 이끌고 있음을 검증하여 TTF 중심의 연구와 AST의 적절한 사용(faithfulness on appropriation; FOA)을 중심으로 하는 두 연구에 대한 통합 모델을 제시하였다.

• Environmental and Resource Economics Review
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• v.27 no.4
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• pp.639-666
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• 2018

This paper analyses the investment options of groundwater development project under water price uncertainty. The optimal investment threshold price which trigger the investment are calibrated base on monopolistic real options model. Stochastic dynamic model is set to reflect the uncertainty of water price which follows the GBM (Geometric Brownian Motion) process. Our finding from non-cooperative investment decision model is that uncertainty of water price could deter the groundwater investment by considering the existence of option values. For policy markers, it is easy to manage 'charges for utilization of groundwater' rather than 'performance guarantee ratio' when managing groundwater investment with pricing policy. And it is necessary to make comprehensive and well-designed policies considering the characteristics of regional groundwater reservoir and groundwater developers.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.3-10
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• 2003

In this paper, a partially blind signature schemes baled on EC-KCDSA is proposed and we applied it to design an electronic check payment system. Because the proposed partially blind signature scheme uses elliptic curve cryptosystem, it has better performance than any existing schems using RSA cryptosystem. When issuing a refund check, one-time pad secret key is used between the bank and the customer to set up secure channel. So the symmetric key management is not required.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.4
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• pp.429-438
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• 1986

In this paper we have designed and implemented a real-time, full-duplex SBC (sub-band coding) codec at 16kbps using a high speed digital signal processor, NEC 7720. The SBC codec employs a QMF(quadrature mirror filter) filter bank based on the tree structures of two-band analysis-synthesis pairs to partition speech signal into 4 octabe bands. Computer simulation has been done to investigate the effect of fixed-point computation of the NEC 7720. Three different performance measures, the conventional signal-to-noise ratio, the informal listening test, and an LPC(linear predictive coding)distance measure, have been used in this simulation. The necessary parameters have been optimized through the simulation. The developed hardware and software have been tested in real-time operation using a hardware emulator.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.453-465
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• 2007

With rapid expansion of the water market and growth of water companies, the recent trends in international water industry show that standardization of service activities concerning management of water and wastewater system (ISO/TC 224, to be issued in the second half year of 2007) is expected to have a large influence on the global water market including liberalization of water service market. In the Draft International Standard(DIS) of ISO/TC224, Performance Indicators(PIs) are suggested to estimate the service activities relating to water and wastewater treatment facilities. PIs have been developed in many countries including some international organization(World Bank, IWA and etc.) for service benchmarking. To evaluate public service level and establish plans to improve service level of wastewater utilities, we developed PIs for 120 items and applied them to 10 sewage utilities in the consideration of their scales, circumstances and conditions. In this study, we verified the applicability of the developed performance indicators(PIs). So, we concluded that PIs developed for the purpose of this study can be a useful tool applicable to objective evaluation of the service level of sewage utilities. Using the evaluation tool of PIs developed, it can also be used as a benchmarking tool in this industry as well as for enhancing the efficiency of operation and management of the sewage system. It will also contribute to the water resource management through determination of investment priorities based on the evaluation results and to raising international competitiveness of the domestic sewage utilities to meet the future opening of the water market.

• Korean Journal of Community Nutrition
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• v.11 no.2
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• pp.240-252
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• 2006

A survey was implemented to suggest basic data for assuring the safety of cooked foods in foodbank operations. A questionnaire consisted of total 48 items including general characteristics, basic inputs and perceived importance/performance of sanitary management. One hundred twenty-eight responses among the 267 nationwide foodbanks were used for the statistical analysis. About forty-one percent of foodbanks was operated a period of 1-3 years and 43.0% of them were managed by social welfare organizations. The number of staff was only 0.5 person per operation with the whole responsibility and 1.0 with additional work, and thus most of the work was managed by volunteers. Job satisfaction was shown to be moderate and was affected by specialty and salary mostly. The facilities and equipment in foodbanks were not enough to operate and freezers/refrigerators were the top priority to supplement. Most of the respondents attended a nationwide level sanitary education program (79.7%); but complained not enough frequency of education (90%). The sanitary status of the donated foods was considered as satisfactory but some safety practices had to be improved, including personnel expenses and operating costs in the district level, a sanitary awareness of the donors and a general management of the facilities arid equipment. An assessment on sanitary management resulted in an overall average of 4.45 out of 5 points in importance and 3.85 in performance showing the high level of sanitation perception in foodbank managers. From the IPA analysis, the fields found to be improved were sanitation management during cooking and temperature control as well as cleanliness and sanitation of both transport vehicle and refrigerator/freezer. To secure the food safety in foodbanks, consequently, personnel support, supplement of facilities and equipment, intense sanitation education and development of sanitation management program is needed.