• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.73-82
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• 1999

In this research, an experimental study is presented to check the possibilities of offshore structures monitoring using AE techniques. The underwater transducer and preamplifier are fabricated. And, it is proved that this unit can be used for the detection of AE in offshore structures. Wave propagation studies have shown that supplementary attenuations due to seawater are significantly reducing the detection range of the sensors. It excludes the possibility of offshore structures monitoring with a small number of sensors. We conclude that AE waves would be correctly detected for a path of about 3m. Tubular joints have been tested in air and underwater using simulated elastic wave. Ability of AE techniques to detect and locate cracks early in their evolution has been demonstrated. Several parameters of AE generation have been set in evidence. It has also been shown that crack development goes with an increase of AE parameter. Conclusively, it is shown that AE techniques can provide practical alternatives to present methods being used for inspection of deep-water offshore structures undergoing structural degradation due to fatigue crack growth.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.575-581
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• 2007

웹사이트를 어떻게 디자인했을 때 지식을 보다 효율적으로 전달할 수 있는가에 많은 관심이 쏠리고 있다. 최근의 몇몇 커뮤니케이션 연구들은 인터넷의 독특한 정보 전달 구조인 하이퍼텍스트 구조가 정보 전달에 있어서 핵심적인 영향을 끼치고 있으며, 따라서 하이퍼텍스트를 어떤 방식으로 구조화하는지에 따라 지식의 전달 내용도 바뀔 수 있다고 주장하고 있다. 이 연구는 이러한 학자들의 의견과 궤를 같이 하여, 이용자의 사전 지식의 차이에 따라 비선형적 웹사이트 구조가 구조적인 지식과 선언적인 지식을 전달하는 데, 어떠한 차이점을 가지는지를 시험적으로 검증한 예비 조사적 연구이다. 관련된 기존 문헌 연구를 통해, 사전 지식이 높은 이용자는 선형 구조보다는 비선형 웹 구조를 통해서 구조적인 지식을 습득하는 데, 유리할 것이고 사전 지식이 낮은 이용자는 선형 구조보다는 비선형 웹구조를 통해서 학습할 때, 선언적인 지식을 습득할 확률이 높을 것이라고 예상되었다. 이를 소규모 집단 실험으로 검증한 결과, 통계적으로 유의한 수준은 아니었지만 비선형적 웹구조는 구조적인 지식을 증가시키는 경향성이 발견되었다. 또한 사전 지식이 높은 이용자 역시 비선형 구조에서 높은 구조적 지식을 습득하는 경향성이 있었다. 그러나 선언적인 지식의 경우에는 웹 구조의 영향이 크게 상관이 없는 것으로 나타났다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.92-95
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• 2003

본 논문에서는 철도차량 견인전동기에 대한 상태진단 및 상시감시 기술에 관하여 소개하였다. 권선의 절연상태 진단을 위한 비파괴 시험법에서는 부분방전량 Q에 대한 평균열화도 $\Delta$로 표현되는 D-Map에 의해 잔여 절연내력(residual dielectric strength)을 예측하고, 기기의 운전이력측면에서 기동-정지 횟수와 열적, 전기적 및 열싸이클 스트레스 등에 의해 각 열화 인자를 고려한 운전시간에 기반한 N-Y 수명예측을 수행한다. 그리고 견인전동기의 전류에 대한 온라인 상태감시를 통해 베어링 고장, 고정자 및 전기자 고장, 고장 또는 전동기축 손상에 기인하는 비정상 운전상태 의 감지를 수행한다.

• Journal of the Korea Computer Industry Society
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• v.9 no.5
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• pp.183-190
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• 2008

Recently, according to development of information-oriented society, internet application technology on electricity electron controled technology fields are diversified and the necessity of remote measurement by internet is gradually increased. In this paper, to meet in these necessity we design and implementation of remote measurement system using internet embedded module, which was developed for on-line measurement of various kinds of analogue data. This system is consisted of two parts greatly, hardware module for measurement and software module to control it. The advantage of this system is that users can acquisition the remote data of temperature and illumination etc. without extra serve pc easily. In order to test the validity of the proposed system, we examine the response and operating characteristic about several states. As a result of the test, we proved the effectiveness of it.

• Knowledge Management Research
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• v.14 no.2
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• pp.71-88
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• 2013

The aim of this study was to investigate why people voluntarily contribute knowledge to others, primarily strangers, in the electronic network of practice for job examination expected potential competing. This paper is organized as follows. First, we introduce the electronic network of practice which is the knowledge sharing community for job examination, and discuss the key issues for understanding knowledge sharing in these networks on the basis of individual motivations, relational capital, sense of community, and sense of rivalry to develop a research model for this study. To test the proposed research model, we adopted the survey method for data collection, and examined our hypotheses by applying the multiple regression analysis method to the collected data. Our unit of analysis was the individual. The findings of this study show that the intention of knowledge sharing is influenced by the reputation and the enjoy helping as the factors of individual motivations, by the reciprocity as the factor of relational capital, and by a sense of rivalry as a psychological factor. Lastly, contributions of this study and future research opportunities are also discussed.

• Membrane Journal
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• v.27 no.4
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• pp.367-373
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• 2017

Pressurized membrane module systems, including hollow fiber type of Microfiltration (MF) and Ultrafiltration (UF) membranes are being increasingly used in drinking water treatment due to their high removal efficiency of pathogen. However, when fibers are damaged in pressurized membrane system, the pathogen will be able to penetrate the membrane. Therefore, it is essential to guarantee the regulatory requirements for water quality by an effective on-line or off-line condition integrity monitoring methods. Recently, pressure decay test (PDT) which is one of membrane integrity tests has been reflected to drinking water treatment plants using pressurized membrane module. In this paper, three different method were used to perform PDT and three different sensitivity values were analyzed through experiments. Three types of direct integrity test methods were applied to pressure feed side, filtrate side and bidirectional pressure decay test. The results of these experiments show that the sensitivity was increasing when the volume of pressurized gas was decreasing. The sensitivity is inversely proportional to the gas volume. Furthermore, it is desirable to increase pressure difference between feed side and permeate side in order to achieve higher sensitivity in the PDT by membrane damage.

• Journal of Korea Game Society
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• v.5 no.2
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• pp.19-27
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• 2005

The core price policy of on-line game marketing are FPP(Fixed Pre Paid model and PPU(Pay Per Use) model. These two models have been a on-line game company's billing system and a fundamental of MMORPG in Korea. However, they took root billing system only for first movers recently. In now, the market share of several first movers is exceeding 80%, late movers witch have same billing system cannot take part in pair competition. Even though in MMORPG, many games of late movers were favorably noticed by a lot of gamers during Evaluation. Test, a lot of companies are bankrupt before make business. Late Movers declare free game first thing, they maintain their existence and win over customers in on-line game market. And next, they guarantee item selling, give multiple experience value and game money, at last, induce their customers to pay service. As it makes trouble between pay user and free user, and it linked up with the collapse of game contents balance that designed for FPP billing system, And then meet unexpected result which reduction of game life cycle. In this Paper, we classified several contents services based on game contents, and suggested contents premium services which adopted low cost strategy lead to micro payment. we hope it will apply to late movers' new billing system in MMORPG.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.31-43
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• 2006

As of March 2005, the standard of traffic signal controllers became effective. The standard presents specifications and functions of a traffic signal controller which collects traffic information, sends it to the traffic control center, and controls traffic signal with adequate traffic signal timing provided by the traffic control center. Since the controllers by the previous standard lack parts compatibility and have different control functions and communication protocol, the maintenance cost has been increased. Also, some important functions like conflict detection have not worked out perfectly. To overcome these disadvantages, first of all, this standard secures hardware compatibility. Conflict detection method has been enhanced. Communication protocol to the traffic control center was included in the standard. With this standard, independent maintenance system and prompt treatment of hardware malfunctions becomes possible. Also, the unified intersection traffic control method will increase traffic safety.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.93-102
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• 2005

This paper proposes an approach to verify signature using autonomous self-organized Neural Network Model , fused with fuzzy membership equation of fuzzy c-means algorithm, based on the features of the signature. To overcome limitations of the functional approach and Parametric approach among the conventional on-line signature recognition approaches, this Paper presents novel autonomous signature classification approach based on clustering features. Thirty-six globa1 features and twelve local features were defined, so that a signature verifying system with FE-SONN that learns them was implemented. It was experimented for total 713 signatures that are composed of 155 original signatures and 180 forged signatures yet 378 original signatures written by oneself. The success rate of this test is more than 97.67$\%$ But, a few forged signatures that could not be detected by human eyes could not be done by the system either.

• Journal of Engineering Education Research
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• v.12 no.4
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• pp.38-45
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• 2009

The purpose of this study is to explore improvable proposal of instruction through analyzing learners' needs and satisfaction for college of engineering. Based on the online survey date with undergraduate students in Seoul National University, recognition difference between students in college of engineering and all students in SNU was identified. Among several factors influenced on learners' satisfaction in class, it is shown that satisfaction to facilities is higher than any other factor related to instruction. Generally, satisfaction with teaching in class is lower while satisfaction to an extrinsic support to students is high. Therefore, instructors should be more concerned about teaching in class. Learners' satisfaction with instructors' feedback to assignments and tests is significantly higher in college of engineering. However, learners' satisfaction with the progress of classwork and assignment students should perform regularly is lower than one in other colleges.