• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.98-103
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• 1992

The dynamic and static torque characteristics of a three dimensional control panel installed behind a guide panel were investigated in a wind tunnel. The panel was tested for various wind speeds, angles of attack and positions of the panel. The effects of the rotational speed and the amplitude of the sinusoidal motion were also studied. The increasing rate of torque coefficients with the angular position of the panel is small when the panel remains in the wake region, but is linear when it reaches the external stream. In case of a sinusoidal motion of the pannel, a hysterisis appears in the dynamic torque. The hysterisis becomes strong as the wind speed and the angular speed of the panel increase. The unsteady torque is considered quasi-steady when the angular speed is less than 5.5rad/s, i.e. the reduced frequency is less than 0.035.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.557-563
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• 2007

Rain-wind induced cable vibration can cause serious problems in cable-stayed bridge. External dampers attached to the cables have become widely accepted as an effective means for stay-cable vibration suppression. For very long stay-cables, however, such damper systems are rendered ineffective, as the dampers need be attached near the end of cables for aesthetic reasons. A recent study by the authors proposed that a movable anchorage system is replaced direct fixed support of the cable with a support through a bearing and damper. This paper extends the previous work by adding active control system to mitigate the cable vibration. The response of a cable with the proposed active control system is obtained and then compared to those of the cable with and without an external passive damper. The results show that the active control system can provide superior protection than the passive control system for a cable vibration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.539-549
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• 2017

In this paper, experimental studies on the shroud separation were performed to investigate characteristics of the shroud separation at mach 3. Shroud separation tests were carried out in the vertical free-jet wind tunnel that is capable of testing separable structures. A shroud model was miniaturized to meet test objectives and test section dimensions of the wind tunnel. Pneumatic Locking and separation mechanisms were designed considering external force due to free stream. High speed cameras were used to record the shroud motion and unsteady shock patterns over the deploying shrouds during the shroud separation process. Also, unsteady pressures on the nose surface were measured by using the pressure sensors. Through the tests, the measurement data necessary for researches on the shroud separation technology were obtained. Shroud separation behaviors and characteristics of unsteady pressure on the nose surface for each external flow conditions were analyzed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1145-1158
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• 1994

A three-dimensional, finite difference, numerical model with free surface was developed on ${\sigma}$-coordinate. A semi-implicit numerical scheme in time has been adopted for computational efficiency. The scheme is essentially independent of the stringent stability criteria (CFL condition) for explicit schemes of external surface gravity wave. Implicit algorithm was applied for vertical shear stress, Coriolis force and pressure gradient terms. The reliability of the model with vertically variable grid system was checked by the comparison of simulation results with analytic solution of wind-driven currents in a one-dimensional channel. Sensitivity analysis of differencing parameters was carried out by applying the model to the calculation of wind-driven currents in a square lake.

• Fire Science and Engineering
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• v.30 no.1
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• pp.6-11
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• 2016

This study analyzed the performance of smoke exhaustion installed to secure the life safety from the smoke each opening modes, as performing the simulation on the Jeju regions generating to strong windy using CONTAM. We assessed the effectiveness of the system under conditions of high external winds as well as an ambient wind conditions. It also assessed the relative effectiveness of opening all vents versus opening only those vents which served rooms in which the fire was located. This study revealed external winds exerted a substantial impact on the performance of the smoke ventilation system. It was found that opening the ventilation system in the room containing the fire resulted in a greater performance than opening vents in both fire in all rooms. The reduced performance of the smoke ventilation system upon the opening of all vents is thought to be due to the intrusion of outside air, and the establishment of unfavorable air circulation, caused by the negative pressure generated in the building.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.644-648
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• 2004

In the present study were examined numerically and experimentally the off-design performance characteristics on an axisymmetric plug nozzle with variable throat area. In this nozzle concept, its throat area can be changed by translating the plug into the axial direction. First, a mixed-expansion plug nozzle, in which two expansion parts are arranged both inside and outside, was designed by means of the method of characteristics. Second, the CFD analysis was verified by the cold-flow wind tunnel test. Third, its performance characteristics were evaluated over a wide range of pressure ratio from half to double throat area through the design point, using the CFD code verified by the wind tunnel tests. It was made clear from the study that not so critical thrust efficiency losses were found and the maximum thrust efficiency loss was at most approximately 5 % under off-design conditions without external flow. This result shows that a plug nozzle can give the altitude compensation even under off-design geometry operations. However, shock waves were observed in the inner expansion part under the doubled throat area operation and thus some thermal problems may be caused on the plug surface. Furthermore, collapse of cell structure on the plug surface was observed with external flow (around Mach number 2.0) as it became lower pressure ratio below the design point and the fact may result in big efficiency loss regardless of geometrical configuration.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.4
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• pp.159-168
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• 2018

In recent, mobile augmented reality game which has been attracting high attention is considered to be an good approach to increase immersion. In conventional augmented reality-based games that recognize target objects using a mobile camera and show the matching game characters, touch-based interaction is mainly used. In this paper, we propose an intuitive interaction method which manipulates a deformable game object by moving a target image of augmented reality in order to enhacne the immersion of the game. In the proposed method, the deformable object is intuitively manipulated by calculating the distance and direction between the target images and by adjusting the external force applied to the deformable object using them. In this paper, we focus on the cloth deformable object which is widely used for natural object animation in game contents and implement natural cloth simulation interacting with game objects represented by wind and rigid objects. In the experiments, we compare the previous commercial cloth model with the proposed method and show the proposed method can represent cloth animation more realistically.

• Journal of Korean Medical classics
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• v.35 no.2
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• pp.99-120
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• 2022

Objectives : To analyze symptoms of olfactory dysfunction caused by COVID-19 from a Korean Medical Perspective. Methods : Previous studies dealing with olfactory dysfunction accompanying COVID-19 were studied and analyzed for general characterization. Physiology and pathology of olfactory functions within the classical texts of Korean Medicine were collected and analyzed, through which symptoms of olfactory dysfunction in COVID-19 were examined. Results : Olfactory dysfunction manifested in high ratios in the early stages of confirmed COVID-19 cases, at times independent of other nasal symptoms such as blockage or discharge. There was a high chance of loss of taste being accompanied, while mental problems such as a tendency to have difficulty concentrating were present as well. In most cases, recovery took one to two weeks. From a Korean Medical perspective, physiology of olfactory function is closely linked to the Lungs, Ancetral Qi[宗氣], and the Heart, while its dysfunction could be explained by pathological factors such as Wind-Cold, Fire stagnation, Qi deficiency, Wind stroke, etc. Conclusions : In the context of external contraction disease[外感病], olfactory dysfunction could be caused by problems in the Lungs and Stomach that are responsible for breathing, or the Heart which is involved in recognizing and differentiating scent. General characteristics of COVID-19 imply it to be closely related to the Heart. In clinical application, overall symptoms need to be considered in diagnosis and treatment planning, after which further approaches could made to determine the problem to be of the Lung and Stomach, or of the Heart.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.230-240
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• 2022

In general, a high tension on the anchor and chain is placed when a ship at anchor is subjected to heavy weather. Mariners have to pay attention to whether dragging anchor occurs to keep the safety of the ship at anchorage since it is difficult to maintain the stable motion of ship and it causes collisions with other ships nearby. In this paper, the ship motion against the external forces was shown to obtain the fundamental data about characteristic of holding power due to nature of seabed at anchor, so practical trials were carried out in rocky area and muddy area using a trial ship around coastal area of South Korea. In muddy seabed, holding power showed reasonable tension values depending on the distance from anchor position of continuing swing motions of a ship corresponding to wind force. Meanwhile in rocky seabed, tension values on the chain appeared very high occasionally regardless of the distance from the anchor position and seemed to exceed its holding power to be the breaking strain of the chain although weather was not in a severe condition. Therefore, some of the cables laid on the seabed were presumed to be caught in a crack on the rock. It is assumed that even a small amount of external force may cause the chain to break in a moment in rocky seabed. Additionally, wind and current forces had a somewhat contradictory effect on holding power of the ship between them.

• Journal of Korean Medical classics
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• v.36 no.4
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• pp.93-108
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• 2023

Objectives : This paper aims to study the characteristics of zhongfeng treatment by examining the eight principles of zhongfeng treatment in the Zhongfeng Jiaoquan of Zhang Shanlei along with Zhang Bolong's treatment of 'Yangxu Leizhongfeng[Yang deficiency pseudo Wind damage]' which is missing from the eight principles. Methods : The treatment methods in the Zhongfeng Jiaoquan was organized in the order of cause, characteristic, symptom, treatment, and precautions, in order to analyze features that were emphasized by Zhang in zhongfeng treatment. Results : First, treatment for bizheng is to 'open and close', then apply methods of 'qianyang jiangqi(潛陽降氣)' and 'zhenni huatan(鎭逆化痰)' while that for tuozheng is to 'lianyin yiye(戀陰益液)' accompanied by medicinals that 'qianzhen xutang(潛鎭虛陽)'. Second, treatment for ganyang shangnizheng is to 'qianzhen rougan', while for tanzian yongsezheng, one must 'dangdi(蕩滌)' for those who are strong in qi, 'xiehua(泄化)' for those who are weak in qi, while for those who have qinizheng[qi reverse syndrome] to 'shunqi(順氣).' Third, for deficiency in xinye and ganyin, one must 'yuyin yangxue[育陰養血]', while for deficiency in shenyin, one must first 'qianjiang shena[潛降攝納]' then slowly apply the method of 'ziyang shenyin[滋養腎陰]' if there is no phlegm turbidity. Fourth, in order to communicate the meridians and unfold collaterals, if the pathogen is external, apply the method of 'yangxue tongluo[養血通絡]', while if the pathogen is internal, calm by doing 'qianyang zhenni[潛陽鎭逆].' Fifth, in order to treat pseudo zhongfeng caused by yang deficiency, one must 'lianyin gutuo[戀陰固脫]' while using medicinals that 'jiangxiang[潛降]'. Conclusions : Treatment of zhongfeng in the Zhongfeng Jiaoquan diverged from 'wenjing sanhan', the usual approach to zhongfeng which sees it as external, and established the 'qianjiang zhenshe [潛降鎭攝]' treatment method based on the internal wind theory. It suggests a new Korean Medical pathology based on theories of Western medicine, and introduces eight principles in treating zhongfeng, which would influence the treatment of zhongfeng in the future.