• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 추계 학술대회논문집
• /
• pp.149-156
• /
• 2007

A three-dimensional inviscid flow solver has been developed based on unstructured meshes for the simulation of steady and unsteady flowfields around a generic fighter aircraft and for the investigation of the aerodynamic interference between the external stores and the tail surfaces. The flow solver is based on a vertex-centered finite-volume method and an implicit point Gauss-Seidel relaxation scheme. To validate the flow solver, calculations were made for a steady flow and the computed results were compared with experimental data. An unsteady time-accurate computation of the generic fighter aircraft with external stores at transonic flight conditions showed that the external stores cause undesirable vibration on the horizontal tail surface due to the mutual interference between their wake and the horizontal tail surface. It was shown that downward deflection of the trailing edge flap significantly reduces the undesirable interference effect.

• 한국항공우주학회지
• /
• 제39권9호
• /
• pp.823-831
• /
• 2011

항공기 탑재 장비의 발달에 따라서 기존 운용 중인 항공기에 새로이 개발된 외부장착물을 추가하거나 교체하는 경우가 빈번히 발생하고 있다. 외부 장착물의 추가 및 변경은 기존 항공기의 전체적인 공력특성을 심각하게 변화시킬 수 있다. 따라서 요구되는 장착물 배열, 형상에 따른 유동 및 공탄성 현상의 파악은 항공기 개발단계 및 항공무장의 추가적인 개발 시 필수적으로 요구된다. 본 연구는 유체-공력 연계기법을 이용, 외부장착물의 형상에 따른 F-5 항공기 수평미익의 공탄성 특성변화에 대하여 검토하였다. 공기력 계산을 위하여 FLUENT 코드를, 구조 동특성 해석을 위하여 ABAQUS 코드를 사용하였으며, 전역지지 방사기저함수를 적용한 Code-bridge를 이용하여 입력 자료의 보간 및 사상을 수행하였다. 해석 결과 고려된 비행조건에서 외부장착물의 형상에 따른 수평미익의 공탄성 특성에 미소한 차이는 있었으나 플러터는 발생하지 않는 것으로 나타났다.

• 항공우주시스템공학회지
• /
• 제9권1호
• /
• pp.28-34
• /
• 2015

Armed aircraft of a basic trainer class installs external stores under wing box by using pylon and performs an operation such as weapon delivery and jettison, and should be designed to withstand all kinds of loads applied to external stores. The static strength test of pylons and wing box was performed to assess the static strength of pylon and their support structures for substantiation. Based on the test, the structures were verified to fully satisfy a given design requirement. In this paper, methods of test load generation of wing box and pylon, evaluation of test result data and design result of test set-up were presented. Comparing the FEM analysis with the same test data can lead to good match and reasonable deviation between both. Finally, based on the test and the analysis, the static strength of test article was substantiated and the reliability and effectiveness of analysis math model were obtained.

• 한국군사과학기술학회지
• /
• 제26권1호
• /
• pp.83-90
• /
• 2023

The external store fitted to the aircraft may affect the flight characteristics and flight safety of the aircraft, which requires the analyses and testing on it. The purpose of this study is to identify and analyze types of failures that can affect the flight safety of aircraft due to the installation of external stores, and to check the flight safety of aircraft through dropping tests of the external stores. After identifying the types of failures that could affect the flight safety of the aircraft, the criticality was calculated to analyze the effect on the flight safety of the aircraft. Four types of failures were selected: unintentional dropping, failure of dropping, unintentional main wing deployment, and release of tail wing restraint of the external store, which are considered to affect the flight safety of the aircraft due to the operation of the external store. As a result of the aircraft's flight safety analysis on the failure types, the criticality requirements were met. Based on this, after obtaining the airworthiness certification, the drop test was successfully performed to confirm the flight safety of the aircraft by mounting an external store on the aircraft. However, in addition to the four hazards carried out in this study, the real external stores of the military aircraft may have various factors affecting the flight safety of the aircraft, so further research will be needed.

• 한국항공우주학회지
• /
• 제36권3호
• /
• pp.211-219
• /
• 2008

본 연구에서는 삼차원 비정렬 비점성 유동 해석 코드를 이용하여 전투기 형상의 외부 장착물이 꼬리 날개에 미치는 공력 간섭효과에 대한 연구를 수행하였다. 수치적 기법으로는 격자점 중심(vertex-centered)에 기초한 유한체적법과 시간 적분을 위한 내재적인 point Gauss-Seidel 반복 계산법을 사용하였다. 해석 코드의 검증을 위해 전투기 형상에 대한 정상 유동 계산을 수행하였으며 결과를 실험 데이터와 비교하였다. 외부 장착물의 후류(wake)를 정확히 포착하기 위해 예상되는 후류 영역에 대해 국부적인 격자 조밀화를 수행하였으며 천음속 영역에서의 비정상 유동 해석을 통해 외부 장착물에서 발생하는 후류가 수평꼬리날개에 미치는 간섭효과를 확인하였다. 공력 간섭효과를 감소시키기 위한 대안으로는 뒷전 플랩 꺽임각(trailing edge flap deflection)을 고려하였으며 이에 대한 정량적인 감소효과를 제시하였다.

• 한국실내디자인학회논문집
• /
• 제25권4호
• /
• pp.23-34
• /
• 2016

The purpose of this study was to investigate the influential factors of space marketing, and then to empirically analyze how they were reflected on the facade elements of sports stores. In order to achieve such a purpose, the research was firstly based on the perspective of space marketing to extract various features into 4 types of factors, namely sensuous factors, differentiated external appearance factors, image-associating factors and story-creating factors. Secondly, this study extracted the elements of facade design for sports stores including architectural elements, visual elements and display elements. Thirdly, it clarified the correlation of the influential factors of space marketing with the external space elements of sports stores. Fourthly, the qualitative analysis method was applied to analyze eight selected cases in Busan and eight selected cases in Fukuoka, Japan in order to explore the various different methods of expression of facade design. Lastly, the study found that the stores in Busan mostly take advantage of contrasting effects to deliver a strong visual impression to customers in the sensuous factors. Besides, the facade shapes in Busan were designed to be straight in order to enhance the main doors with its distinguished formative features to maximize the effective expression of the differentiated external factors, along with other expression methods of the image associating and story creating factors. This was done to associate with the brand identity in comparison with the stores in Fukuoka.

• Structural Engineering and Mechanics
• /
• 제8권2호
• /
• pp.181-191
• /
• 1999

This paper presents an investigation of the mode localization and frequency loci veering phenomena in an aircraft with disordered external stores. Two theoretical analyses are carried out to study the occurring mechanism of the two phenomena: condensation technique in the subspace spanned by modes of interest and geometric mapping theory in the complex plane. Two simple criteria for predicting the occurrence of the mode localization and frequency loci veering are put forward. The prediction of the phenomena by our theoretically proposed criteria is in good agreement with that obtained through numerical calculations of characteristic solutions of the disordered system.

• 한국생활과학회지
• /
• 제23권1호
• /
• pp.101-122
• /
• 2014

In this study, the Pine & Gilmore(1998) and Schmitt(1999, 2003), based on previous studies. Recent trends in large department stores and distribution outlets, discount stores and large retail centers, such as the consumer's experience is divided into internal and external fashion brand stores navigation study. Fashion Brand Stores are defined as the inside of the fashion brand store of the form that sells only the products of a fashion company's brand. Meanwhile, shopping center is defined as all the places at the inside and out of the shopping center excluding the inside of the fashion brand store. Likewise, definitions are clarified as such for use. As for the research method for this study, semi-structured focus group interviews were used since they could provide many more data compared to in-depth interviews. Accordingly, data was collected while carrying out free discussions while two to three subjects listened to each other's opinion regarding the key words raised by the interviewer and while thinking about their experience at the inside and outside of the fashion brand stores. As for the subjects, female consumers between the ages of 20 and 50 were targeted, and the interviews conducted with four, seven, four and three women in their 20s, 30s, 40s and 50s, were used, respectively. Likewise, there were a total of 18 subjects. Exploratory Study of Customer Experience area was classified into integration of significance and categorization. In particular, the contents were classified into elements of experience inside the fashion brand stores and fashion brand stores outsider experience in the shopping center elements and the elements of the common experience of fashion stores and shopping centers based on the results concerning the key contents identified in-depth from the customer aspect. The key experience elements at the inside of fashion brand stores were identified as VMD experience, emotional experience, and experience of the service provided by sales representatives. As for the key experience elements at the shopping center which is at the outside of the fashion brand store, they included service scape experience, cultural event experience, playful behavior experience. Meanwhile, elements of common experience included educational experience and exclusivity experience and human respect experience, which demonstrated some difference in terms of the contents.

• 한국군사과학기술학회지
• /
• 제10권4호
• /
• pp.73-80
• /
• 2007

Modern aircraft are required to carry various external stores mounted at different locations on the wing. Sometimes the attachment of stores to an aircraft wing leads to flutter speed reduction, which is a very severe aeroelastic problem. In order to suppress structural vibration and expand the flutter boundary of the aircraft with stores, it is necessary to investigate the main problems and characteristics of them. In addition, active vibration control may be required because passive vibration isolators show limited capabilities for the various wing/store configuration. In this paper, therefore, the flutter stability to the various wing/store configurations was investigated and active vibration control of wing/store model was performed using a piezoelectric actuator.

• 한국군사과학기술학회지
• /
• 제16권1호
• /
• pp.74-80
• /
• 2013

In this paper, we have proposed a vapor cycle refrigeration system as a cooling system to provide cooling air to the aircraft external reconnaissance stores. In the proposed vapor cycle system, receiver which prevents refrigerant from subcooling was eliminated and thermal expansion valve was replaced with electronic expansion valve. The vapor cycle refrigeration system is aimed to provide cooling air to the reconnaissance stores which is added to the aircraft in the form of external store. The wide temperature range of ambient air from the flight conditions can decrease the cooling performance and can make the refrigeration system unstable in low ambient temperature. Performance characteristics of the vapor cycle refrigeration system has been experimented under air conditions which is derived from the flight envelope. From the experiments, the vapor cycle refrigeration system has been proved to provide enough cooling air to the reconnaissance equipment and to be stable under all the flight conditions.