• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.282-283
• /
• 2017

본 논문은 (주)효성 중공업연구소에서 국책과제를 통해 자체 개발한 MMC(Modular Multi-level Converter) type ${\pm}12kV$ 25MVA HVDC 시스템에 대하여 실증단지 구축 및 commissioning test에 대한 소개를 한다. 제주에 구축된 HVDC 실증단지는 국내 유일의 MMC type 전압형 HVDC 시스템이며 11-레벨의 AC 출력 전압을 형성하는 2개의 컨버터가 Back-to-Back 형태로 구성되어 있다. 각 컨버터의 AC 출력단은 각각 계통과 풍력발전단지에 연계되어 풍력발전단지에서 생산된 전력을 계통으로 전송하는 역할을 한다. 주요 AC/DC Yard 기기들로는 AC 고조파 필터, 밸브리액터, DC 리액터, 변압기, CGIS등이 있다. HVDC 의 commissioning test를 위해 IEEE, IEC, Cigre TB 등의 문서들을 종합 분석하여 당사의 시스템에 알맞은 시험절차서와 검증항목을 준비하였다. 본 논문에서는 당사에서 준비한 시험절차서 및 검증항목에 대하여 소개하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.11b
• /
• pp.961-964
• /
• 2002

일반적으로 Web Service란 표준 인터넷 프로토콜을 이용하여 외부에 노출된 비즈니스 기능을 프로그램적으로 접근하는 방식으로 간단한 메소드 호출뿐만 아니라 복잡한 비즈니스 프로세스까지 수행이 가능하고, 한번 배포된 Web Service는 인터넷으로 접근할 수 있는 곳이면 어디서든지 접근 및 호출이 가능하다. 현재 Web Service 구현에 있어 최대의 당면 과제는 보안문제로서. 인터넷을 이용해서 이동하고 있는 많은 양의 데이터를 안전하게 지킬 수 있는 방법의 모색에 초점이 맞추어져 있다. 이러한 보안 문제를 해결하기 위해 SAML(Security Assertion Markup Language), XKMS(XML Key Management Specification), XAML(Transaction Authority Markup Language), BTP(Business Transaction Protocol), XLANG 등을 이용한 여러 가지 방법이 시도되고 있다. 본 논문에서는 SAML을 이용한 보안 솔루션을 분석하고, SAML을 이용하여 SSO, Back Office Transaction 등의 어플리케이션을 구축하여 시뮬레이션 결과를 보이고자 한다.

• Science of Emotion and Sensibility
• /
• v.25 no.2
• /
• pp.79-86
• /
• 2022

With external air pollution forcing many people indoors, new methods of facilitating healthier indoor life are necessary. This study, therefore, investigates the effects of indoor oxygen concentration and respiration methods on biosignals and cognitive ability. The study included twenty healthy subjects who inhaled air through a mask from a gas delivery system. All subjects were asked to perform three types of breathing (nasal, oral, and oral breathing with high oxygenation) and respond to cognitive stimuli (rest close eye, rest open eye, 1-back and 2-back working memory tasks). The changes in cognitive load according to respiration were analyzed by measuring response time, accuracy, and biosignals to stimuli. The result showed that, in all three respirations, heart rate significantly increased with the increase in cognitive load. Also, in oral respiration, the airway respiration rate significantly increased according to the increase in cognitive load. The change appeared to compensate for insufficient oxygen supply in oral respiration during cognitive activity. Conversely, there was no significant change in airway respiration rate during oral respiration with a high concentration oxygen supply as in nasal respiration. This result suggests that a high concentration oxygen supply might play a role in compensating for insufficient oxygen concentration or inefficient oxygen inhalation, such as oral respiration. Based on the results of this study, a follow-up study is necessary to determine the impact of changes in the autonomic nervous system, such as stress and emotions, to find out more precise and comprehensive effects of oxygen concentration and breathing type.

• Journal of Korea Port Economic Association
• /
• v.20 no.2
• /
• pp.169-185
• /
• 2004

It is an urgent problem that Korea logistics enteprises' expansion of advance into China market and the logistics network establishment between Korea and China to back up the former are to be solved. Accordingly, the purpose of this study is to deduce the subjects to establish the logistics network between Korea and China, and to evaluate the priority order. The results of this research are as follows: First, we conducted face-to-face interviews on the advisery group in China and Korean enterprises which advanced into China, and drew out 6 promoting subjects to build the logistics network between the two. Second, the AHP model was adopted, which is a multi-criteria?multi-hierarchical decision making method, to draw out the weight and priority order of the deduced 6 promoting items. Third, the resultant priority order of the promoting subjects is as follows: No.1 - to establish the distribution & logistics support center by region(0.3900); No.2 - to support various taxes in investing the logistics business abroad(0.1980) ; No.3 - to improve the management of CIQ(0.1958); No.4 - to back up the joint-venture of logistics firms(0.1169); No.5 - to enhance trade and foreign policies to deregulate the entry into logistics markets(0.0536); No.6 - to construct the logistics information system of China(Northest Ssia)(0.0458). This paper resulted in finding out Korea logistics enterprises that have not secured their own inland-transport network in China and the actual difficulties of Korean enterprises with using the inferior network that advanced into China. These problems were developed into the analysis adopting the AHP method, and the significancy of this paper is to present the priority order of promoting problems using a sophisticated technique.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.4 no.2
• /
• pp.152-161
• /
• 2009

Insider threat is becoming a very serious issue in most organizations and management is responsible for security implementation. This study is to develop a personnel security management indicators in the areas of Personnel Assurance, Personnel Competence, and Security Environment and protection against insider threats. In this study, the information security management system.

• Journal of Biomedical Engineering Research
• /
• v.27 no.6
• /
• pp.323-331
• /
• 2006

The purpose of this study was to investigate the effect of performing a cognitive task during treadmill walking on the stride rate variability. Ten university students(age $24.0{\pm}0.25$, height $172{\pm}3.1cm$, weight $66{\pm}5.3kg$) were participated in dual task experiments which consist of both walking alone and walking with a cognitive task. Two-back task was selected for the cognitive task since it did not have learning effect during the experimental procedure.3D motion analysis system was used to measure subject's position data by changing walking speed with 4.8, 5.6, 6.4, 6.8, and 7.2 km/hr. Stride rate was calculated by the time between heel contact and heel contact. Accuracy rate of a cognitive task during walking, coefficient of variance, allometric scaling methods and Fano factor were used to estimated the stride rate variability. As the walking speed increased, accuracy rate decreased and the logarithmic value of Fano factor increased which showed the statistical difference. Thus it can be concluded that the gait control mechanism is distracted by the secondary attention focus which is the cognitive task ie. two-back task. Further study is needed to clarify this by increasing the number of subject and experiment time.

• Journal of the Korean Data and Information Science Society
• /
• v.9 no.2
• /
• pp.345-355
• /
• 1998

The back propagation(BP) algorithm allows multilayer feedforward neural networks to learn input-output mappings from training samples. It iteratively adjusts the network parameters(weights) to minimize the sum of squared approximation errors using a gradient descent technique. However, the mapping acquired through the BP algorithm may be corrupt when errorneous training data are employed. In this paper two types of robust backpropagation algorithms are discussed both from a theoretical point of view and in the case studies of nonlinear regression function estimation and handwritten Korean character recognition. For future research we suggest Bayesian learning approach to neural networks and compare it with two robust backpropagation algorithms.

• Journal of the Korean School Mathematics Society
• /
• v.2 no.1
• /
• pp.15-30
• /
• 1999

For the purpose of turning learners' locus of control into internal-controllable variables, counseling materials were developed, and attribution counseling was given. The counseling effects were practically confirmed by way of teaching and evaluation in the actual classes, and furthermore the efforts to provide learners with successful experiences in learning were repeatedly made. As a result, the conclusions are as follows: 1. The procedure of Individual counseling for learning attribution based on individual standard grades and data of the variable order of merit apparently shows learners that if learners are to try their best in learning, they will surely go far in terms of learning in the near future. 2. The procedure of Individual counseling for teaming attribution based on achievement distribution in individual behavior-oriented fields suggests to learners that how to learn is as important as how much effort they make. Surely enough, learners are required to make more effective and efficient efforts, considering their own learning abilities. 3. With the above 1, 2 procedures involved, learners have attributed locus of causality in achievement to their internal-controllable causes. 4. With preparatory assignments according to learner's abilities provided, even slower learners came to be assured that their constant efforts could give rise to success in learning achievement. 5. Above all, it was confirmed that the learners' struggling attitude might well have a significant correlation with achievement success. The learners who are willing to attribute locus of causality in achievement to their internal-controllable causes or strenuous efforts and intrinsic motivation tend to be convinced that they can address themselves to whatever faces them, so they can set up specific learning goals fit for their abilities. Accordingly, they will bit by bit acquire successful experiences (often called 'Aha' experiences) and in turn, feeling the senses of self-efficacy and self-esteem enough to push their efforts even further, they can grow to form a positive self-concept. With one successful experience after another fed back into learners, they are gradually motivated to bring the oncoming achievement expectation to a higher level. To conclude, it is necessary that instruction leading to internal-controllable attribution should be provided, inducing learners to recognize success and failure in learning achievement as a result of their strenuous efforts.

• Journal of the Korean Society of Radiology
• /
• v.11 no.4
• /
• pp.273-278
• /
• 2017

Among 45 patients of herniation of intervertebral disc with $L_4$ to $L_5$ herniation, who underwent infrared thermography, the number of female was larger than male and the age of 50s was highest. From the results measured from the distribution table, we have confirmed that there was no significant difference depending on sex and age (p> 0.05). The region of the highest ROI temperature for patients with $L_4-L_5$ intervertebral disc prolapse was the back of the posterior right tibia, and followed by the back of the left shin bone-below the front right knee-below the front left knee. There was a significant difference depending on the measured site. The average ROI temperature for patients was $30.30{\pm}0.50$ whereas that for normal persons was $31.20{\pm}0.58$, yielding the temperature difference of $0.66{\pm}0.59$ between the two groups. The ROI of patients was lower than $31.20{\pm}0.58$ (p <0.05) because the significance of the sample, which has been obtained from the results of a sample t-test, was less than 0.05 (p <0.05). From further researches, it may necessary to develope the methodology for correcting data regarding thermal environment and, in addition, to develope a new thermal index based on it. Therefore, we can confirm that pre-treatment for infrared thermography is very important in order to minimize the procedure for correcting data. It is required that radiologists who inspect disc herniations should carefully observe and consider the patients during their measurements.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.2
• /
• pp.179-186
• /
• 2012

In the automobile industry, reducing the weight is the most important objective for reducing air pollution and improving the fuel efficiency. For this reason, the application of aluminum sheets is increasing. When the sheets are applied to the automobile, using inappropriate variables for the material, product design, and press processing can generate tearing, wrinkling, and spring-back problems, which are the main types of failure in the manufacturing process. Therefore, it is necessary to reduce these failures by harmonizing the many variables and strictly managing the processes. In this research, we study the theoretical plasticity instability of Al5454 and obtain the forming limit diagram (FLD) using MATLAB. Moreover, we compare the theoretical FLD with an experimental FLD obtained from a stretching test.