• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.737-743
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• 2013

The small-scaled onsite generators such as photovoltaic power, wind power, biomass and fuel cell belong to decarbonization techniques. In general, these generators tend to be connected to utility systems, and they are called distributed generations (DGs) compared with conventional centralized power plants. However, DGs may impact on stabilization of utility systems, which gets utility into trouble. In order to reduce utility's burdens (e.g., investment for facilities reinforcement) and accelerate DG introduction, the advanced operation algorithms under the existing utility systems are urgently needed. This paper presents the advanced voltage regulation method in power systems since the sending voltage of voltage regulators has been played a decisive role restricting maximum installable DG capacity (MaxC_DG). For the proposed voltage regulation method, the difference from existing voltage regulation method is explained and the detailed concept is introduced in this paper. MaxC_DG estimation through case studies based on Korean model network verifies the superiority of the proposed method.

• Journal of Information Display
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• 제6권3호
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• pp.18-21
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• 2005

A new technology for reducing photolithography process from a four step to a three step process in the fabrication of TFT LCD is introduced. The core technology for 3-mask-TFT processes is the lift-off process [1], by which the PAS and PXL layers can be formed simultaneously. A different method of the lift-off process was developed in order to enhance the performance of efficiency with conventional positive and not negative PR which is the generally used in other lift-off process. In addition, the removal capacity of the ITO/PR in lift-off process was evaluated. The evaluation results showed that the new process can be run in conventional TFT production condition. In order to apply this new process in existing TFT process, several tests were conducted to ensure stability of the TFT process. It was found that the outgases from PR on the substrate in ITO sputtering chamber do not raise any problem, and the deposited ITO film beside the PR has conventional ITO qualities. Furthemore, the particles that were produced due to the ITO chips in PR strip bath could be reduced by the existing filtering system of stripper. With the development of total process and design of the structure for TFT using this technology, 3-mask-panels were achieved in TN and IPS modes, which showed the same display performances as those with the conventional 4mask process. The applicability and usefulness of the 3-mask process has already verified in the mass production line and in fact it currently being used for the production of some products.

• 한국디지털건축인테리어학회논문집
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• 제3권1호
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• pp.39-49
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• 2003

The height provisions, by the urban planning, describe the hightest height per width division, also define oblique line limitation by road without mentioning the highest per width division. Therefore this study will be a basic model for the standard of measuring the highest height per width division analysizing the propriety of current standard of oblique limitation. This technique is prepared to prevent the confusion and to complements the existing planning method. Therefore, it takes more time to establish this new method and to apply it to the existing condition. This study reviewed density control in District Units Plan, based on the guidelines of density, which included height, ratio of total floor to ground area, and land distribution. This study aims to provide efficient analysis by using current oblique limitation provisions Thus, proving the area rations of general residential areas are decreasing. Since the purpose of the District Units Plan is to avoid confusion and help ease the existing problematic conditions which have risen from the two above-mentioned conventional systems, further observation and research on these areas are necessary.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1076-1089
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• 2021

Among the currently used knowledge-based authentication methods for smartphones, text and graphic-based authentication methods, such as PIN and pattern methods, use a display unit and a touch function of the display unit for input/output of secret information. Recently released smartphone form factors are trying to transform into various forms, away from the conventional bar and slate types because of the material change of the display unit used in the existing smartphone and the increased flexibility of the display unit. However, as mentioned in the study of D. Choi [1], the structural change of the display unit may directly or indirectly affect the authentication method using the display unit as the main input/output device for confidential information, resulting in unexpected security vulnerabilities. In this paper, we analyze the security vulnerabilities of the current mobile user authentication methods that is applied atypical form factor. According to the analysis results, it seems that the existing display-dependent mobile user authentication methods do not consider emerging security threats at all. Furthermore, it is easily affected by changes in the form factor of smartphones. Finally, we propose countermeasures for security vulnerabilities expected when applying conventional authentication methods to atypical form factor-based smartphones.

• 동력기계공학회지
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• 제21권6호
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• pp.94-100
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• 2017

Due to the environmental problems caused by the greenhouse effect, regulation of $CO_2$ emissions is getting stronger day by day. In paricular, regulations of automobiles $CO_2$ emissions are being strengthen. However, existing $CO_2$ measurement methods do not reflect the environment and operating conditions on actual roads. Emissions of $CO_2$ can be increased by various conditions such as environmental condition(temperature and humidity) and driver's tendency(aggressive and passive). Therefore it is necessary to reflect the conditions of various actual roads such as 5-cycle test method on behalf of the existing $CO_2$ emission measurement method. The 5-cycle measurement method has five test modes; FTP-75, HWFET, US06, SC03, Cold FTP-75. The method reflects the following three environments and operating conditions as compared to conventional method; Using heater at low temperature, Aggressive driving such as rapid acceleration or deceleration, Using air conditioner at high temperature. Because of these various conditions of each test cycle, the 5-cycle method can reflect actual environments and operating conditions. This paper attempt to analyze $CO_2$ emission characteristics based on the results measured through the 5-cycle mode and develop the correction formula that can derive the results of the 5-cycle test method using existing test methods. As a result, the developed correction formula is expected to reduce $CO_2$ emissions and cut down expense for testing 5-cycle mode.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.672-674
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• 2011

에지는 영상의 특징을 분석함에 있어서 중요한 정보를 포함하고 있다. 에지 검출은 컴퓨터비전과 영상처리 등의 분야에서 많이 활용하고 있으며, 초기에 사용된 방법들 가운데서 sobel, prewitt, roberts method 등이 대표적이다. 이러한 기존의 방법은 밝기의 기울기가 큰 변화지점은 쉽게 검출하지만, 선택적인 방향성 에지 검출이 미흡하다. 본 논문에서는 이러한 기존의 에지 검출 방식의 단점을 보완하기 위해 방향성을 고려한 적응 에지 검출 방법을 제안하여, 시험 영상의 에지 성분을 검출하였으며, 시뮬레이션을 통해 그 성능을 확인하였다.

• IEIE Transactions on Smart Processing and Computing
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• 제1권1호
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• pp.17-26
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• 2012

This paper presents an image processing-based validation method for unrecognizable numbers in severely distorted license plate images which have been degraded by various factors including low-resolution, low light-level, geometric distortion, and periodic noise. Existing vehicle license plate recognition (LPR) methods assume that most of the image degradation factors have been removed before performing the recognition of printed numbers and letters. If this is not the case, conventional LPR becomes impossible. The proposed method adopts a novel approach where a set of reference number images are intentionally degraded using the same factors estimated from the input image. After a series of image processing steps, including geometric transformation, super-resolution, and filtering, a comparison using cross-correlation between the intentionally degraded reference and the input images can provide a successful identification of the visually unrecognizable numbers. The proposed method makes it possible to validate numbers in a license plate image taken under low light-level conditions. In the experiment, using an extended set of test images that are unrecognizable to human vision, the proposed method provides a successful recognition rate of over 95%, whereas most existing LPR methods fail due to the severe distortion.

• 전기학회논문지
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• 제65권9호
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• pp.1583-1589
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• 2016

This paper proposes an improved spread spectrum time domain reflectometry (ISSTDR) using time-frequency correlation and reference signal elimination method in order to have more accurate fault determination and location detection than conventional (SSTDR) despite increased signal attenuation due to the long distance to cable fault location. The proposed method has a two-step process: the first step is to detect a peak location of the reference signal using time-frequency correlation analysis, and the second step is to detect a peak location of the correlation coefficient of the reflected signal by removing the reference signal. The proposed method was validated through comparison with existing SSTDR methods in open-and short-circuit fault detection experiments of low voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• 전기학회논문지P
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• 제58권4호
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• pp.410-415
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• 2009

With the implementation of electric power industry reform, the utilities are looking for effective ways to improve the economic efficiency. One area in particular, the equipment maintenance, is being scrutinized for reducing costs while keeping a reasonable level of the reliability in the overall system. Here the conventional RCM requires the tradeoff between the upfront maintenance costs and the potential costs of losing loads. In this paper we describe the issues related to applying so-called the "Reliability-centered Maintenance" (RCM) method in managing electric power distribution equipment. The RCM method is especially useful as it explicitly incorporates the cost-tradeoff of interest, i.e. the upfront maintenance costs and the potential interruption costs, in determining which equipment to be maintained and how often. In comparison, the "Time-based Maintenance" (TBM) method, the traditional method widely used, only takes the lifetime of equipment into consideration. In this paper, the modified Markov model for maintenance is developed. First, the existing Markov model for maintenance is explained and analyzed about transformer and circuit breaker, so on. Second, developed model is introduced and described. This model has two different points compared with existing model: TVFR and nonlinear customer interruption cost (CIC). That is, normal stage at the middle of bathtub curve has not CFR but the gradual increasing failure rate and the unit cost of CIC is increasing as the interruption time is increasing. The results of case studies represent the optimal maintenance interval to maintain the equipment with minimum costs. A numerical example is presented for illustration purposes.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.999-1008
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• 1999

본 논문에서는 날로 정보화 되는 환경 하에서 다수의 결재권자들이 존재하는 사무실의전자결재 시스템에 관해 고찰한다. 먼저 전자결재 시스템의 종류를 분류해 보았으며, 지금까지 개발된 기존의 다중서명 방식들을 이용한 전자결재 시스템을 분석하였다. 또한 새로운 다중서명 방식을 제안하여 이 방식을 전자결재 시스템에 적용시킴과 동시에 기존 방식과의 비교 분석을 통해 본 방식의 장점을 살펴보았다. 본 논문에서는 이산 대수 문제의 어려움에 근거한 디지털 다중서명 방식을 이용하여 전자결재 시스템에 적용한 것으로 통신 횟수 및 기능적 측면에서 기존 방식보다 안정적이므로 전자결재 시스템에 적합한 방식이라 하겠다.