• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2584-2586
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• 2000

A drum level control is one of the most important control systems in thermal power plant. The control objective of drum level of boiler in thermal power plant is to maintain drum level at constant set-point regardless of disturbance such as main steam flow. The implemented drum level controller is the cascade PI controller. The important factor in drum level controller is the parameters of two PI controllers. The tuning of PI controller parameter is tedious and time-consuming job. In this paper, the relay feedback Ziegler - Nichols tuning method extended to auto-tune cascade PI drum level controller. Finally, the simulation result using boiler model in Power Plant shows the validity of auto-tuned cascade PI controller.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.263-269
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• 2018

In this study, a selective inverter operation between a 2-level voltage source converter (VSC) and a 3-level T-type VSC (3LT VSC) is proposed to improve the efficiency of a 3LT VSC. The 3LT VSC topology, except for its neutral-point switches, has similar operations as that of the 2-level VSC. If an operation mode is changed according to efficiency, the efficiency can be improved because efficiencies of each methods are depending on current and MI (Modulation Index). The proposed method calculates the power losses of the two topologies and operates as the having lower losses. To calculate the losses, the switching and conduction losses based on the operation mode of each topology were analyzed. The controller determined the operation mode of the 2- or 3-level VSC based on the power loss calculated during every cycle. The validity of the proposed control scheme was investigated through simulation and experiments. The waveform and average efficiency of each method were compared.

• Journal of Information Technology Applications and Management
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• 제21권3호
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• pp.119-133
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• 2014

Prior to the 2000s, internal control had not been among the high priority issues in the management's agenda. Since then, however, it has become one of the hottest issues, and has received a significant attention as the means of improving the transparency, sustainability, and competitiveness of a company. The objectives of this paper are to examine if there has been any noticeable changes in the level of internal controls of Korean companies before and after the 2010, and to analyze the underlying drivers and issues thereto. Accounting manipulation and moral hazard were among the factors to cause the Korean financial crisis in 1997 and 2008. Since then, the capital market has had a strong pressure on Korean companies to enhance the transparency of management and accounting while the government has made the laws, requirements, and recommendations to alleviate the moral hazard problems of management and enhance the accounting transparency. Both market and government have driven companies to put more priority on the reliability of financial reporting and the compliance of applicable laws and regulations. Thereby, the market and governmental forces has led companies to enhance the level of internal controls which contribute to the reliability of financial reporting and the compliance The pressure on companies to enhance the level of internal controls may be different across industries. The capital market and government experiencing the severe financial crisis in 1997 and 2008 put even more pressure on financial companies such as banks to upgrade the reliability of financial reporting and the compliance of regulations to the global level than on non-financial companies. A survey is performed on the changes in the level of internal controls of 54 major companies consisting of 10 financial and 44 non-financial companies in Korea. The survey results show that the average level of internal controls of Korean companies has noticeably improved and that the change in the level of control environment factor is higher than that of IT control factor. The analysis on the industry differences shows that financial companies increased the level of control environment factor more than non-financial companies did while non-financial companies upgraded the level of IT control factor more than financial companies did relatively. Among internal control categories, the most improved area since the economic crisis is "Risk Assessment." The global best practices for risk management have been developed primarily in the financial industry and then spread to other industries. The general level of control practices of Korean companies has been improving significantly, but still appears below the global advanced practices.

• 동아시아식생활학회지
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• 제11권4호
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• pp.268-273
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• 2001

This study was performed to investigate the effects of HBM(Healthy Body Maker) on the weight loss and serum cholesterol level of rats. Twenty male Sprague-Dawley rats weighing 200$\pm$5g were grouped into 2. Rats were raised for 6 weeks with diet containing 0% and 5% of HBM. 1. There were no clinical signs for all the experimental period(6 weeks) in 0% and 5% groups. 2. At 3 and 6 weeks. body weight of 5% HBM group was significantly lower than that of control group. respectively(p<0.05, p<0.01). 3. At 4 weeks. the level of MCHC of 5% HBM group was significantly higher than that of control group(p<0.01) And at 6 weeks the level of RBC and Hct of 5% HBM group were significantly higher than those of control group(p<0.05) 4. At 6 weeks. the level of serum cholesterol of 5% HBM group was significantly lower than that of control group. 5. Absolute liver weight of 5% HBM group was significantly lower than that of control group(p<0.05). 6. Minor subaceous sickness of liver cell in the control group appeared but no symptom of liver cell in 5% HBM group. It is concluded that HBM was a safe and effective diet food which aided in inducing weight loss in rat without any observed harmful clinical side effects.

• 기본간호학회지
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• 제15권4호
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• pp.531-538
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• 2008

Purpose: The purpose of this study was to identify factors influencing Vancomycin-resistant enterococcus infection control among nurses in intensive care units. Method: Data were collected from August 15 to October 14, 2007 from 188 nurses working in intensive care units. The nurses answered a 26 item-questionnaire, which included management of the cohort (14 items), hand washing (6 items) and management of the environment (6 items). Descriptive statistics, t or F test, ANOVA, and multiple regression analysis were used with SPSS PC+ 14.0 to analyze the data. Results: The participant's level of awareness of Vancomycin-resistant enterococcus infection control was 3.87; that of compliance was 3.74. Significant factors influencing the level of compliance with Vancomycin-resistant enterococcus infection control were'the level of the awareness' and 'the type of intensive care unit'. These two variables accounted for 21.0% of variance for compliance with the Vancomycin-resistant enterococcus infection control among the participants. Conclusion: In order to develop a strategy to increase the compliance with Vancomycin-resistant enterococcus infection control, it is necessary to be concerned about 'the level of the awareness', 'the type of intensive care unit;', and 'experiences of caring for patients with Vancomycin-resistant enterococcus'.

• 한국지역사회생활과학회지
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• 제18권2호
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• pp.247-263
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• 2007

This study was complied to analyze the professional agricultural techniques level and to suggest a desirable direction for the professional education system for women farmer. The research was conducted by using in-field surveys and interviews. Data was gathered by questionnaire from 147 women farmer in five specialized crop regions: strawberry, cucumber, rose, apple, and oyster mushroom. The results obtained are as follows. First, the technique levels in computer usage and electronic commerce, machinery usage, pesticide and fertilizer utilization, facility automation, and eco-agricultural cultivation were low. Second, the demand for professional education, evaluated through technique level by standard management diagnosis, was recognized. Areas of concern included: cucumber (temperature control, carbonic acid gas control, grading, funds management), strawberry (light control, soil temperature control, irrigation watering, shipping), rose (temperature control, light control, funds management, cooperated management), oyster mushroom (growth cabinet sterilizer), and apple (flower bud pinching, defloration, fruit thinning, funds management). Based on the results of this study, the following are suggestions for the planning of a professional education system for women farmer. First, it needs to address formal education in marketing, machinery usage, facilities automation, and techniques in pesticide and fertilizer utilization. Second, it needs to be a multi- level program with appropriate terminology at every level which is suitable to each age and ability of women farmer. Third, it needs a more comprehensive manual developed by need analysis of women farmer and a larger lecturer pool for professional education.

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.301-310
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• 2017

For further development of passive control systems to dissipate larger seismic energy and prevent the structures from earthquake losses, this paper proposes an innovative two-level control system to improve behavior of chevron braced steel frames. Combining two Knee Braces, KB, and a Vertical Link Beam, VLB, in a chevron braced frame, this system can reliably sustain main shock and aftershocks in steel structures. The performance of this two-level system is examined through a finite element analysis and quasi-static cyclic loading test. The cyclic performances of VLB and KBs alone in chevron braced frames are compared with that of the presented two-level control system. The results show appropriate performance of the proposed system in terms of ductility and energy dissipation in two different excitation levels. The maximum load capacity of the presented system is about 30% and 17% higher than those of the chevron braced frames with KB and VLB alone, respectively. In addition, the maximum energy dissipation of the proposed system is about 78% and 150% higher than those of chevron braced frames with VLB and KB respectively under two separate levels of lateral forces caused by different probable seismic excitations. Finally, high performance under different earthquake levels with competitive cost and quick installation work for the control system can be found as main advantages of the presented system.

• 한국산학기술학회논문지
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• 제16권1호
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• pp.429-437
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• 2015

본 연구는 대학생의 스마트폰 중독 경향에 따른 신체활동량, 수면, 주의력 조절 및 자기조절학습과의 차이와 관계를 파악하기 위한 서술적 조사연구이다. 자료수집은 269명의 대학생을 대상으로 구조화된 설문지를 통해 조사하였고 SPSS 18.0 프로그램을 통해 자료를 분석하였다. 연구결과 대상자의 스마트폰 중독수준은 성별에 따라 차이가 있었고, 스마트폰 중독성향이 강할수록 성적과 자가통제력은 낮고, 스마트폰 사용 시간이 길었다. 스마트폰 중독수준과 신체활동량, 수면의 질 및 주의력 조절능력이 유의한 차이가 있었고, 스마트폰 중독정도가 높을수록 신체활동량과 자기조절학습능력 및 수면의 질이 낮은 경향이 있었고, 주의력 조절은 높게 나타나는 경향을 보였다. 이상의 결과를 통해 대학생의 스마트폰의 과다사용으로 일상적 건강과 학습능력이 저하될 수 있으며 이를 방지하기 위한 다양한 차원에서의 스마트폰 중독예방 전략이 필요함을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1261-1264
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• 1996

This paper presents the design of a neural network based PWM technique for a three level inverter of electric trains. A three-level inverter has several advantages compared with a two-level inverter in this application. In viewpoint of correcting unbalance of DC-link voltage, a novel method is developed and verified in computer simulation.

• 대한한의학방제학회지
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• 제12권1호
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• pp.195-208
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• 2004

Objective: This study was conducted to investigate the effects of Aconiti Tuber on the plasma IL-6 and $TNF-{\alpha}$ level in mice stimulated by intracerebroventricular(I.C.V.) Injection of Lipopolysaccharide(LPS). Method: 6 mice were assigned to each of the normal group, the control group, and the experimental group. In the normal group only saline was administered intragastrically, and in the control group LPS was injected intracerebro-ventricularly 1 hr after intragastric administration of saline. In the experimental groups (Aconiti Tuber 0.5g/kg, Aconiti Tuber 1.0g/kg, Aconiti Tuber 3.0g/kg) each sample was administered intragastrically to mice 1 hr prior to the stimulation by LPS I.C.V. Injection. To measure the plasma IL-6 and $TNF-{\alpha}$ level of mice, their blood samples were collected from retro-orbital plexus, immediately centrifuged at $4^{\circ}C$, and plasma was removed and stored frozen at $-83^{\circ}C$ for later determination of plasma IL-6 and $TNF-{\alpha}$. Result : 1. LPS I.C.V. Injection increased plasma IL-6 level significantly in a dose-dependent manner compared with normal group(P<0.01). The plasma IL-6 concentration reached a significant maximal level about 1 hr after LPS I.C.V. Injection(P<0.001). LPS I.C.V. Injection increased plasma $TNF-{\alpha}$ level significantly in a dose-dependent manner(P<0.05). The plasma $TNF-{\alpha}$ concentration reached a significant maximal level about 1 hr after LPS I.C.V. Injection(P<0.001). 2. Sample A group to which Aconiti Tuber(0.5g/kg) was administered intragastrically 1 hr prior to the stimulation by LPS I.C.V. Injection showed insignificant lower plasma IL-6 level in 1 hr than control group(P<0.0635), and sample B group (Aconiti Tuber 1.0g/kg) showed significant lower plasma IL-6 level in 1 hr than control group(P〈0.05), and sample C group (Aconiti Tuber 3.0g/kg) showed significant lower IL-6 plasma level in 1 hr than control group(P<0.01). 3. sample A group to which Aconiti Tuber(0.5g/kg) was administered intragastrically 1 hr prior to the stimulation by LPS I.C.V. Injection showed insignificant lower plasma $TNF-{\alpha}$ level in 1 hr than control group(P>0.05), and Both sample B(1.0g/kg) and sample C(3.0g/kg) groups showed significant lower $TNF-{\alpha}$ plasma level in 1 hr than control group(P<0.01). These data revealed that Aconiti Tuber might have the anti inflammatory effect by reducing the plasma IL-6 and $TNF-{\alpha}$ level in a dose dependent manner in mice LPS I.C.V. Injection.