• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.61-62
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• 2001

현재 연근해 어선에는 정격하중 1∼2톤의 크레인이 주로 보급, 설치되고 있는데, 이들 어선에서 사용하는 크레인은 안정성이나 동적 특성에 관한 조사, 분석이 거의 없어 크레인을 이용한 어로작업시에 많은 위험이 수반되고 있다. 따라서, 연근해에서 사용되고 있는 크레인의 진동저감 대책과 안정적이고 효율적인 사용을 위해서는 크레인의 동적응답 특성에 대한 규명이 필요하고, 또한, 향후 어로 크레인의 사용을 활성화시켜 어로작업의 효율화와 노동력 절감을 모색하기 위한 연구가 절실히 요구된다. (중략)

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.83-85
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• 2018

저전력에 사용되는 Flyback 컨버터에서는 일반적으로 트랜스포머의 보조권선을 통하여 구동 IC에 필요로 하는 전력을 공급한다. 하지만, USB PD와 같이 5~20V의 넓은 출력전압을 가지는 경우 IC Vcc 정격 전압을 위하여 Linear regulator 사용이 필수적이나, 이는 소자발열 및 시스템 효율을 저하시킨다. 따라서, 본 논문에서는 출력전압 변동에 따라 변압기의 보조권선을 변환 시키는 회로를 제안하고자 한다.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.153-160
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• 2008

The combustion behaviors of the blends of Korean anthracite, bituminous coal and their blends were studied with a thermogravimetric analyzer. Concerning the burning profiles of the anthracite-bituminous coal blends in TGA, it has been observed the independent burning of two coals without any interaction between two coals. With the blends of 50% anthracite with 50% bituminous coal in weight basis, the combustion tests in a utility boiler have been carried out for the analysis of the combustion and operational characteristics by increasing the power output from 134 MW to 197 MW. The stable combustion has been observed in a boiler. With the increase of power output, the exhaust gas temperature was exceeded the design value of $430^{\circ}C$, so the combustion air was taken from atmosphere instead of the boiler penthouse.

• Fire Science and Engineering
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• v.34 no.2
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• pp.64-71
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• 2020

In this paper, the fire risk of a single-phase induction motor under a locked-rotor condition is described. In general, motor failure occurs in the locked-rotor condition owing to poor rotation of the rotor. Large inrush current flows when a motor starts, which is approximately 2-15 times larger than the rated current. In a single-phase induction motor under the locked-rotor condition, a large current that corresponds to the inrush current flows continuously through the stator winding. Such an overcurrent rises the temperature inside the stator winding, and thus the insulating material may catch fire. In this study, the restrained operating condition of the single-phase induction motor was simulated. Further, the degree of the overcurrent and temperature rise in the stator winding was measured. The experimental results, confirmed that the overcurrent was seven times larger than the rated current and the fire commenced at a temperature of approximately 300 ℃ inside the stator winding.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.4
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• pp.327-333
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• 2015

Wind turbines, in the case of less than rated wind speed, is controlled to achieve maximum power. MPC(Maximun Power Control) method, by controlling the rotational speed of the generator, is a method to achieve maximum power but should know the wind speed. However, for several reasons, there have been proposed methods of estimating the wind speed rather than measuring wind speed. TSR(Tip Speed Ratio) is needed to know to estimate the wind speed. However, a complex interaction formula has to be solved to find a TSR. Therefore, many methods have been suggested to solve a complex interaction formula. In this paper, the new method has been proposed to simplify the complicated interaction formula by using the regression method. Matlab/Simulink is used to simulate and to verify the proposed method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.1
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• pp.23-30
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• 2017

Currently, road lightings are installed with less than 400W of existing metal halide lamps. These road lightings are being replaced by energy-saving lightings. Induction lamps are expected to be more actively replaced with targets for tunnel lighting and high ceiling lighting. Therefore, it is necessary to develop high efficiency, high power induction lamps system. In this study, the gas type & pressure, amalgam type were designed for the high power of the induction lamps. And induction lamp system was optimized through electrical, optical characteristics analysis. It is optimized to the gas pressure 300~350 [mmHg] for the discharge tube of high power induction lamp and ferrite core. The driving circuit matching was completed with a induction lamp using indium amalgam. The rated power consumption of the induction lamp was optimized with 250 W (rated ${\pm}10%$)

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.34-38
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• 2016

Recently, electric propulsion systems are been increasingly used in large cruise ships and merchant vessels. When abnormal electrical conditions occur in the motor of an electric propulsion ship, they can cause serious damage to the motor and propeller shaft. Research on abnormal conditions of propulsion motors used in electric propulsion vessels and electric ships difficult to find. In this study, a mathematical model of the electric propulsion system is proposed to analyze transient phenomena that occur in the case of electric propulsion motor or propeller shaft malfunction. A synchronous motor was used in the MATLAB computer simulation of this study. In the event of electrical malfunction of the electric propulsion motor at rated operation, over current occurs in the condition of 1 phase ground, over torque occurs at 3 and 2 phases ground and over current and torque occur when exciting power fails at rated operation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.407-414
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• 2016

As wind turbines are getting larger in size with multi-MW capacity, the blades are getting longer, over 40 m, and hence the asymmetric loads produced during the rotation of the rotor blades are increasing. Some factors such as wind shear, tower shadow, and turbulence have an effect on the asymmetric loads on the blades. This paper focuses on a method of modeling the dynamic load acting on a blade because of thrust variation under wind shear. A method that uses thrust coefficient is presented. For this purpose, "wind shear coefficient of thrust variation" is defined and introduced. Further, we calculate the values of the "wind shear coefficient of thrust variation" for a 2 MW on-shore wind turbine, and analyze them for speeds below the rated wind speed. Then, we implement a dynamic model that represents the thrust variation under wind shear on a blade, using MATLAB/Simulink. It is shown that it is possible to express thrust variations on three blades under wind shear by using both thrust coefficient and "wind shear coefficient of thrust variation."

• Korean Journal of Acupuncture
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• v.28 no.3
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• pp.25-32
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• 2011

Objectives : The purpose of this study is to find parameters to compare the effects of Sa-Am acupuncture with stomach-tonification (ST) and Sa-Am acupuncture with spleen-tonification (SP) on radial pulse. Methods : Forty healthy subjects participated in this study. Radial pulse was measured using 3 dimensional pulse imaging system (DMP-3000) before, right after, 30 minutes after, and 60 minutes after acupuncture. Results : 1. The parameters analysed in this study were changed in the same direction with different degrees by ST and SP. 2. In males, SP manipulation showed significantly increased pulse period and (T-T4)/T, and significantly decreased T1/T, T4/T, T4/(T-T4), and F1~F3 frequencies compared to ST. 3. In females, ST manipulation showed significantly increased (T-T4)/T, and significantly decreased F1~F3 frequencies compared to SP. Conclusions : The parameters analysed in this study may be used to differentiate the effects between ST and SP on radial pulse. These parameters are more strongly affected by SP than ST in males whereas more strongly affected by ST than SP in females.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.225-230
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• 2017

The Sijo provides dynamic rated therapeutic activities in our life. This study aims to search for the literary therapeutic function secreted from the Sijo that ends with a noun. As a result, the noun used at the final sentence secretes a predicative function. This kind of Sijo functions as twelve sound steps, even though it is condensed of just eleven sound steps with one sound step omitted. This functional secretion of Sijo is therapeutic predicate concerned with encoding of literary therapy. Thus it become possible to activate the therapeutic encoding in Sijo or a language by uttering only noun, instead of the predicate. That's because the noun in the last sentence of Sijo permeated in the human body and is done subject, and neuron of the body becomes a predicate, so that the Sijo's subject and the neuron's predicate are fused into a sentence. During the course the human body seems to recognize that the neuron's nucleus analyzes the information of the noun and makes a new sentence. This recognition might also be regarded as a process of encoding that has therapeutic functions secreted from the human body.