• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1275-1276
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1211-1215
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• 2003

Accurate mathematical models of spacecraft components are an essential of spacecraft attitude control system design, analysis and simulation. Gyro is one of the most important spacecraft components used for attitude propagation and control. Gyro errors may seriously degrade the accuracy of the calculated spacecraft angular rate and of attitude estimates due to inherent drift and bias errors. In order to validate this model, nominal case simulation has been performed and compared for the low range mode and high range mode, respectively. In this paper, a mathematical model of gyro containing the relationships for predicting spacecraft angular rate and disturbances is proposed.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.71-77
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• 2016

In this study, the seismic performance of connections between filled composite beam (CG beams) and forming angle composite (FAC) column was experimentally evaluated. First, the bending tests were conducted on two CG beams and the axial tests were conducted on two FAC columns. Then, based on these preliminary test results, the cyclic loading test were performed on two interior connections between CG beam and FAC column. The main difference of two specimens is the plate shape of the CG beam. The test results showed that both specimens achieved the maximum story drift capacity over 0.04 radian which is required for special moment frame.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.03a
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• pp.145-153
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• 2002

A coastwise chemical tanker sailing at full speed has capsized in calm water and whole turing. In the precious paper, we investigated reasons of the accident by demonstrating the proper correction for the free surface effect of the liquid cargo and the bow-sinkage effect. In this paper, we also carry out model experiments of a transverse pressure under the seawater and an outward heel moment according to the heel angle and rudder angle, on the basis of radius of turning circle, ship's speed and drift angle of model ship occurring in turning. It is also shown that the flooding of seawater onto the deck occurring in turning generated a significant outward heel moment and the vertical distance between the center of gravity of the ship and the renter of lateral water drag.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.964-969
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• 2014

In Super Junction MOSFET, Charge Balance is the most important issue of the trench filling Super Junction fabrication process. In order to achieve the best electrical characteristics, the N type and P type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, called Charge Balance Condition. In this paper, two methods from the fabrication process were used at the Charge Balance condition: Trench angle decreasing process and Bottom implantation process. A lower on-resistance could be achieved using a lower trench angle. And a higher breakdown voltage could be achieved using the bottom implantation process. The electrical characteristics of manufactured discrete device chips are compared with those of the devices which are designed of TCAD simulation.

• Korean Journal of Materials Research
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• v.15 no.6
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• pp.361-369
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• 2005

InP(100) crystal surface was irradiated by ion beams with low energy $(180\~225\;eV)$ and high flux $(\~10^{15}/cm^2/s)$, Self-organization process induced by ion beam was investigated by examining nano structures formed during ion beam sputtering. As an ion source, an electrostatic closed electron Hall drift thruster with a broad beam size was used. While the incident angle $(\theta)$, ion flux (J), and ion fluence $(\phi)$ were changed and InP crystal was rotated, cone-like, ripple, and anistropic nanostrucuture formed on the surface were analyzed by an atomic force microscope. The wavelength of the ripple is about 40 nm smaller than ever reported values and depends on the ion flux as $\lambda{\propto}J^{-1/2}$, which is coincident with the B-H model. As the incident angle is varied, the root mean square of the surface roughness slightly increases up to the critical angle but suddenly decreases due to the decrease of sputtering yield. By the rotation of the sample, the formation of nano dots with the size of $95\~260\;nm$ is clearly observed.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.93-100
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• 2020

In this study, structural characteristics were analyzed by combining gravity load and lateral loads such as seismic loads through static analysis of example structures, and the static characteristics of the twisted structure according to the plane rotation angle were also analyzed. Example structures were selected as regular structure, and twisted structures; 1.0, 2.0, and 3.0 degree angle of rotation per story, and static analysis was performed by the load combination case 1 and case 2. As a result the story drift ratio of the twisted-shaped structure also increased as the plane rotation angle per story increased. The eccentricity according to the load combination was the highest in the lower stories of all analysis models, and the eccentricity was found to be larger as the rotation angle decreased. The twisted-shaped structure was more responsible for the bending moment of the column than the regular structure, and the vertical member axial force of all analysis models was almost similar.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.1
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• pp.17-22
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• 2005

The movement of drifting ships on the sea is closely related to marine environmental forces such as waves, currents, winds, etc. To develop a prediction model for trajectories oi drifting ships, an experiment on the movement of drifting ships was carried out in the Southeastern Sea of Korea. Five types of ships including a lire raft and tour ships with G/T 10tons, G/T 2o tons, G/T 50 tons, and G/T 80 tons, were considered in the experiment. The G/T 50 ton class ship was used as a base ship for obtaining the currents, winds and heading angles of ship following the trajectory. The trajectory of each ship was measured by DGPS(Differential Global Positioning System) and collected using APRS(Automatic Position Reporting System) installed on the base ship. The error range in position fix of DGPS are approximately ±1 m. The drift speed of ship in the experiment was between 3％ to 5％ of wind speed and drift direction of ship was deflected by ±90° from wind direction. Also, the heading of drifting ship was normal to wind direction.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.29-37
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• 2002

The purpose of this study is to provide a fundamental data of earthquake resistant design through the estimation of the response modification factor and nonlinear displacement for moment resisting reinforced concrete frames by linear and nonlinear static analysis. The analysis models are designed in accordance with AIK code and then, estimated the response modification factor and nonlinear displacement of the buildings. The parameters such as story numbers(10, 20, 30), plan ratios(1:1, 1:2) and analysis types(2D, 3D) of building structure are chosen for use in this study. After comparing the results of linear and nonlinear static analysis, the response modification factor is obtained as the product of four factors: ductility factor, strength factor, damping factor and redundancy factor. The response modification factor are close to 3.5 in case of 2 span, 4.3 in case of 3 span and 5.0 in case 4 or more span models regardless number of stories and plan ratios. The nonlinear displacement is evaluated from the ratio of story drift angle(nonlinear drift/linear drift). The ratio of story drift angle increases as story numbers increase and the value varies from 5.85 to 9.34.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.335-343
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• 1998

Recently, new experimental criteria for reinforced concrete frame structures in high seismic regions have been reported in United States. The objective of the criteria is to get more reliable test data which are valid to compare with other test data done by different researchers. The criteria precribe test method of specimens, analysis method of test data, and limiting values needed to specimens like drift angle, energey dissipation ratio, stiffness, and strength. These criteria might be usefel to get objective conclusion. Shear wall structures, which belong to one of earthquake resisting systems, also need this kind of criteria. But, the general response of shear wall structures is a little bit different from that of frame structures since shear wall restrains the horizontal displacement caused by horizontal force and increases the stiffness and strength. The objective of this paper is to propose a criterion for limiting drift and energy dissipation ratio of shear walls based on structural testing. These are the most important values for presenting the capacity of shear walls. Limiting drift and energy dissipation ratios were examined for tests on shear walls having ductile type failures. Test data were analyzed and compared to the results for a suggested acceptance criteria that involve a limiting drift that is a function of aspect ratio and a limiting energy dissipation ratio that is a function of displacement ductility and damping.