• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.41-51
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• 2018

Downwash from helicopter rotor blades and external winds from various maneuvering make an unguided rocket change its trajectory and range. For the prediction of the trajectory and range, it is essential to consider the downwash effect. In this study, an algorithm was developed to calculate 6-Degree-Of-Freedom(6 DOF) forces and moments exerting on the rocket, and total flight trajectory of a 2.75-inch unguided rocket in a helicopter downwash flow field. Using Actuator Disk Model(ADM) analysis result, the algorithm could analyze the entire trajectory in various initial launch condition such as launch angle, launch velocity, and external wind. The algorithm that considered the interference between a fuselage and external winds could predict the trajectory change more precisely than inflow model analysis. Using the developed algorithm, the attitude and trajectory change mechanism by the downwash effect were investigated analyzing the effective angle of attack change and characteristics of pitching stability of the unguided rocket. Also, the trajectory and range changes were analyzed by considering the downwash effect with external winds. As a result, it was concluded that the key factors of the rocket range change were downwash area and magnitude which effect on the rocket, and the secondary factors were the dynamic pressure of the rocket and the interference between a fuselage and external winds. In tailwind case which was much influential on the range characteristics than other wind cases, the range of the rocket rose as increasing the tailwind velocity. However, there was a limit that the range of the rocket did not increase more than the specific tailwind velocity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.173-180
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• 2022

The operation and transportation environment for an unmanned aerial vehicle will be completely different from those for the conventional air and ground transportation. The requirement for a traffic management system for its safe operation has been emerging. Accordingly, investigation is being conducted to analyze the danger that unmanned aerial vehicle may encounter during the flight and to provide the countermeasure by the simulation. When the drones operate in an urban environment, they may be affected by the wind around the building. Thus it is essential to predict the influence of the gust and analyze the resulting risk. In this paper, a method for evaluating the safety for a flight mission under the gust is suggested. By using the precise 6-degree-of-freedom flight simulation that is capable of simulating the gust condition, possible deviation from the pre-planned flight path in terms of the attitude orientation will be predicted. A method of quantifying the probability of the flight mission failure will also be presented.

• Journal of Korean Medical classics
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• v.19 no.4
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• pp.147-168
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• 2006

통과대이연화장개빈관우중풍관점적비교연구, 이급기대중풍적분류(以及基對中風的分類), 증상(證狀), 치료(治療), 예후적관점진행분석득출여하결론(豫後的觀點進行分析得出如下結論): 이연파중풍적원인분류위진중풍(李挻把中風的原因分類爲眞中風), 겸중풍(兼中風), 류중풍(類中風), 사중풍(似中風), 종이조취료구분외풍여내풍계기(從而造就了區分外風與內風契機). 대어중풍적원인(對於中風的原因), 장개빈주장배제외풍근한어내풍적관점(張介賓主張排除外風僅限於內風的觀點). 재차기초상(在此基礎上), 설기여조헌가주장진수고갈급진화허시기원인소재(薛己與趙獻可主張眞水枯褐及眞火虛是基原因所在), 대차관점(對此觀點), 장수신적"중풍각전"중, 기유찬동적(旣有贊同的), 역유지비판의견적내용(亦有持批判意見的內容). 대어중풍적증상(對於中風的證狀), 이연근거병사소재분위중장, 중부(中부), 중혈맥(中血脈), 중경등(中經等). 우기대중경증적분류(尤基對中經證的分類), 재기타의서중시무법견도적분류적표준(在基他醫書中是無法見到的分類的標準). 저가이인위(這可以認爲), 타이 "금궤요략" 위의거(爲依據), 시부합내풍적증상분류(是符合內風的症狀分類). 장개빈파비풍적증상종대적방면분위경병화장병(張介賓把非風的症狀從大的方面分爲經病和臟病), 연후재파경병세분위경증화위증(然後在把經病細分爲經證和危證), 장병세분위초경증화위증(臟病細分爲稍經證和危證). 진관경병출현어지체(盡管經病出現於肢體), 이장병출현정신이상(而臟病出現精神異常), 단시경병여장병균유경증화위증(但是經病與臟病均有經證和危證). 저일주장시흔유지이성적. 대중풍적치료(對中風的治療), 이연대체상견지료금원이전적치료방법. 기용신한혹신온거풍화담(旣用辛寒或辛溫去風化痰), 혹용신온발한(惑用辛溫發汗), 혹용고한공리등(或用苦寒攻裏等). 장개빈지출상술방법대원기쇠약적중풍부적합사용(張介賓指出上述方法對元氣衰弱的中風不適合使用), 차장수신지출차시거풍치법실제상부적합내용풍이적합어외풍적치료(且張壽신指出此時去風治法實際上不適合內風而適合於外風的治療). 장개빈인위비풍적원인시진양여진음지허이불시풍담(張介賓認爲非風的原因是眞陽與眞陰之虛而不是風痰), 진관시급성기(盡管是急性期), 여과몰유담증(如果沒有痰證), 타견결반대사용거담지법(他堅決反對使用祛痰之法). 재중풍치료상(在中風治療上), 장개빈인위한다(張介賓認爲汗多), 소변소(小便少), 시진액부족소치(是津液不足所致), 소이수유열증역불요사용삼리지법, 병지출유뇨증시신허소치적위증(幷指出遺尿症是腎虛所致的危證), 종이진일보강조료진액적중요성(從而進一步强調了津液的重要性).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.10
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• pp.639-645
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• 2011

The object of this study is to analyze and evaluate outdoor wind pressure effect in a high-rise residential building when seasonal wind blow on coast area. The target building consists of 3 tower buildings over 250m in height. For the evaluation of the outdoor wind effect, CFD simulation was performed. The results of the simulations are as follows : 1) In that case of high-rise building, horizontal stream is more affected than vertical stream. 2) In case of summer season northeasterly wind, building pressure distributions are unstable and surface pressures of outside are effected respectively. 3) In case of winter season westerly wind, building preassure differentiations are not so much because of screening effects of the B, and the C buildings. 4) In case of winter season northwesterly wind, front wind affects on the A building directly because of no obstacles.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.489-496
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• 2004

The effect of airconditioning and heating system when aircurtains installed in subway electrical rolling stock at entrance door. It blocks cold/hot air of outside. It is good for health with its blocking effect against dusts exhaust fumes, odor bugs and smoke from outside. It always maintains clean and pleasant atmosphere inside. It helps you to have health with its ever-equal temperature distribution at inside. It saves lots of maintenance cost for heating/cooling (about 86$\%$) since it cuts the loss of hot air under heating as well as of cold air under air-conditionin. Customers can feel pleasant go in and out (better than before) with the door. It is an indispensable product for the employers to cut the cost. It makes customers feel pleasant near doors, since it isnt influenced by temperature difference of cold/hot air when the door opens/closes. In electrical rolling stock passenger temperature is a lot different from that the door opens/closes. One of the main aims is to create an acceptable thermal environment without draught problem. Temperature, gradients when aircurtains installed in subway electrical rolling stock at entrance door have been studied. And the temperature measured at 0.1, 0.5, 1.3, 1.7m above the floor. It has been found that temperature, with large fluctuations caused more draught influence.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.47-53
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• 2011

The Electric Multiple Unit (EMU) has many types of door system such as sliding door, plug door etc.al. according to customer's requirements. The sliding door is widely used in Korea but has weak point in the noise problem. In the low operation speed, the noise coming from outer side of the EMU is not an important factor. As the speed is higher than before, noise is increased and make a problem. The main cause of noise is the imperfect air tightness in the EMU. The plug door system has advantages for the noise reduction characteristic in the high speed area. We have been developing electric plug-in door. The door is controlled by Door Control Unit(DCU) following the order of Automatic Train Protection (ATP) that is a kind of train signalling system. DCU has to simultaneously open and close the doors and the operation of it is related to the passengers safety. So DCU is a safety device that is important to reliability and safety. DCU is composed of several devices of control, motor driving, Input/Output, communication and power. In this paper, we will describe the functions, characteristic, requirement, subsystem and test results of DCU used for the electric plug-in door.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1095-1102
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• 2016

This paper presents the results of the design, fabrication and tether test for a gross weight 20 kg tilt-duct VTOL aerial robot. The tilt-duct vehicle, a tri-ducts air-vehicle, which composed of two main tilt ducts for thrust and an aft-fan for pitch attitude control, has been developed as an aerial platform. The research on the air vehicle has been focused on the hover characteristics and controllability to improve the thrust and stability. The tether test for measuring various performance of vehicle and evaluating controllability have been carried out to figure out effects of modified main-prop linkage, actuator, duct configuration and control surfaces.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.341-347
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• 2005

본 논문은 터널에서 화재 발생 시, 시간에 따른 연기거동에 대해 실물실험과 3차원 수치해석을 수행하고 각각의 결과를 비교,검토하였다. 실물실험을 위하여 8.8 kW의 열원과 901iter/h의 연기 발생이 가능한 연기발생장치를 자체 제작하였으며, 대상터널은 길이 570m, 단면적 $64.6m^2,$ 그리고 약 $2\%$의 구배를 가지고 있다. 실험은 외풍의 영향을 줄이기 위해 터널 입,출구에 차단막을 설치하였으며 연기발생장치로부터 20m 간격의 위치에서 20초 간격으로 연기전파, 속도 그리고 온도를 측정하였다. 연기는 60초 경과 후, 연기발생장치로부터 20m 떨어진 위치에 도달하였으며 140초, 180초 및 260초 경과 후, 각각 40m, 60m 및 80m 위치에 도달하였다. 3차원 수치해석의 결과는 터널벽면을 매끈한 표면으로 처리하였을 때, $26.3\~49.5\%$정도 과대 예측하였다. 또한 터널벽면을 일정 조도를 갖는 거친 표면으로 처리한 경우는 $-2.7\~17.6\%$ 오차로 실험결과에 보다 근접하는 결과를 보였다. 따라서 터널 내 연기거동에 대한 3차원 수치해석을 수행할 때에는 벽면조도에 대한 고려가 필요하리라 판단된다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.7
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• pp.586-594
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• 2003

The performance of the condenser installed in the air-conditioning plant room of a high-rise building was studied numerically. The effect of the draft direction on the performance of an air-conditioner was analyzed. The on-coil temperature of the condenser was investigated by varying the arrangement and location o( the condenser in the air-conditioning plant room. The performance of an air-conditioner was also evaluated by using COP (coefficient of performance) and CGPI (condenser group performance indicator). The condenser in an air-conditioning plant room should be arranged in such a manner that the fan of the condenser is facing the outside of the building to exhaust the hot air directly, The model by which the condenser is located at the lower-left end of an air-conditioning plant room can prevent the hot air from reentering, and allow indrafting of fresh air. When the direction of draft is to the frontal face of the building, the performance of the condenser above 30th floor is degraded.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.828-835
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• 2011

The purpose of this study is to analyze and evaluate the 3 types of indoor ventilation methods such as natural, mechanical, and hybrid ventilation in high-rise building which is affected by stack effect and outdoor air pressure. For the evaluation of the ventilation capacity, CFD simulation was performed in a typical high-rise residential building. The results of the simulations are as follows: 1) Natural ventilation method is not enough to the regulation. 2) In case of mechanical ventilation, congested area is occurred but meets the regulation. 3) In case of hybrid ventilation with stack effect, all the areas of indoor meet the regulation and congested area is reduced. 4) In case of high-rise building, the differences of ventilation rate among houses in the building are not large because the mechanical ventilation is main factor.