• 항공우주기술
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• 제1권1호
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• pp.128-134
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• 2002

고속비행 중의 공력가열과 같은 외부 열전달로부터 외피 구조물과 내부 탑재물을 보호하기 위하여, KSR-III의 외피에 단열처리가 필요하였다. 일련의 시험과 분석을 통하여 선정된 단열재인 BMS 10-102는 스프레이 가공 형식의 점착성 물질로서 외피에 도포 후 경화시키며, 낮은 열전달율과 낮은 밀도와 같은 특성을 지녀 우수한 단열효과를 기대할 수 있다. 본 연구에서는 KSR-III 기본형 설계에서 대표적인 다층구조인 노즈 페어링부의 honeycomb 샌드위치 구조에 대한 단열해석을 수행하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.917-918
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• 2012

• 비파괴검사학회지
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• 제37권2호
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• pp.99-105
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• 2017

Many composite materials are used in the aerospace industry because of their excellent mechanical properties. However, the nature of aviation exposes these materials to high temperature and high moisture conditions depending on climate, location, and altitude. Therefore, the molecular arrangement chemical properties, and mechanical properties of composite materials can be changed under these conditions. As a result, surface disruptions and cracks can be created. Consequently, moisture-impregnating defects can be induced due to the crack and delamination of composite materials as they are repeatedly exposed to moisture absorption moisture release, fatigue environment, temperature changes, and fluid pressure changes. This study evaluates the possibility of detecting the moisture-impregnating defects of CFRP and GFRP honeycomb structure sandwich composite materials, which are the composite materials in the aircraft structure, by using an active infrared thermography technology among non-destructive testing methods. In all experiments, it was possible to distinguish the area and a number of CFRP composite materials more clearly than those of GFRP composite material. The highest detection rate was observed in the heating duration of 50 mHz and the low detection rate was at the heating duration of over 500 mHz. The reflection method showed a higher detection rate than the transmission method.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.55-58
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• 2005

The present study aims to design electrically and structurally effective antenna structures in order that the structural surface itself could become the antenna. The basic design concept is composite sandwich structure in which microstrip antenna is embedded and this is termed composite smart structure (CSS). The most important outstanding problem is that composite materials of structural function cannot be used without reducing antenna efficiency. Unfortunately, such materials have high electrical loss. This is a significant design problem that needs to be solved in practical applications. Therefore, the effects of composites facesheet on antenna performances are investigated in the first stage and changes in the gain of microstrip antenna due to composites facesheet have been determined. ‘Open condition’ is defined when gain is maximized and is a significant new concept for the design of high-gain antennas considering bandwidth in practical application. The open condition can be made with the outer facesheet by controlling its position. In the design of CSS, glass/epoxy composites and Nomex honeycomb were used with exploiting open condition. Experiments, confirm that the gain is improved and the bandwidth is also as wide as specified in our requirements. With the open condition, wideband antenna can be integrated with mechanical structures without reducing any electrical performances, as confirmed experimentally here.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.346-349
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• 2005

The present study aims to design electrically and structurally effective antenna structures in order that the structural surface itself could become the antenna. The basic design concept is composite sandwich structure in which microstrip antenna is embedded and this is termed composite smart structure (CSS). The most important outstanding problem is that composite materials of structural function cannot be used without reducing antenna efficiency. Unfortunately, such materials have high electrical loss. This is a significant design problem that needs to be solved in practical applications. Therefore, the effect of composites facesheet on antenna performances is studied in the first stage. Changes in the gain of microstrip antenna due to composites facesheet have been determined. 'Open condition' is defined when gain is maximized and is a significant new concept in the design of high-gain antennas considering bandwidth in practical application. The open condition can be made with any thickness of outer facesheet by controlling its position. In the design of CSS, glass/epoxy composites and Nomex honeycomb were used with exploiting open condition. Experiments, confirm that the gain is improved (over 11 dBi) and the bandwidth is also as wide as specified in our requirements (over 10% at 12.2 GHz). With the open condition, wideband antenna can be integrated with mechanical structures without reducing any electrical performances, as confirmed experimentally here.

• 한국정밀공학회지
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• 제29권3호
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• pp.313-318
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• 2012

Application of composite structures on naval ships strongly depends on the mechanical strength and collapse behavior of the T-joints of the whole structure. Because of the weight advantages over single skin composite and bolt fastening joining, three types of T-joints using both honeycomb sandwich composite and adhesive bonding were suggested to determine the effect of T-joint configuration. It was found that joining with a urethane foam block and overlaminates using the secondary co-bonding technique improves T-joint strength.

• 한국결정성장학회지
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• 제29권6호
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• pp.276-282
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• 2019

본 연구의 목적은 공기청정기의 극세필터(프로필터), 집진필터, 헤파(HAPA-High Efficiency Particulate Air)필터, 탈취필터 등을 사용하는 일반적인 필터의 구조를 분석하고 초미세먼지, 유해가스 및 살균 정화성능을 향상시킬 수 있는 새로운 형태의 공기정화 필터 디자인을 제시하는 것이다. 기존 단계적 여과 필터 형태에 광촉매 필터 시스템을 추가하는 방법으로 연구하였으며, 광촉매 필터는 좌우측의 UV-LED 설치 프레임과 광촉매 코팅 허니컴(honeycomb)프레임 3단 결합구조의 디자인으로 제안했다. 광촉매 필터의 살균소독 효과에 대해서는 향후 연구가 필요하며, 본 연구에서는 공기청정기에 광촉매 필터 적용 및 구조에 대하여 보고하고자 한다.

• 한국전기전자재료학회논문지
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• 제33권1호
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• pp.16-20
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• 2020

In this study, a patterning method using self-aligned nanostructures was introduced to fabricate GaN-based fin-gate HEMTs with normally-off operation, as opposed to high-cost, low-productivity e-beam lithography. The honeycomb-shaped fin-gate channel width is approximately 40~50 nm, which is manufactured with a fine width using a proposed method to obtain sufficient fringing field effect. As a result, the threshold voltage of the fabricated device is 0.6 V, and the maximum normalized drain current and transconductance of Gm are 136.4 mA/mm and 99.4 mS/mm, respectively. The fabricated devices exhibit a smaller sub-threshold swing and higher Gm peak compared to conventional planar devices, due to the fin structure of the honeycomb channel.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2345-2351
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• 2012

Conductive honeycomb-patterned polystyrene (PS) thin films were prepared by the formation of a polyaniline (PANI) thin layer on the surface of the patterned PS thin films using simple one-step chemical oxidative polymerization of aniline. The in situ chemical oxidation polymerization of aniline hydrochloride solution on the patterned structure of the PS films was conducted in the presence of multiwalled carbon nanotubes (MWCNT) to prepare the PANI-MWCNT/PS composite film. The concentration (wt %) of MWCNT was varied in the range of 1%-3% by weight. The dependence of surface morphology of the PANI/PS and PANI-MWCNT/PS composite film to the polymerization time was observed by scanning electron microscopy. The room temperature DC conductivity was obtained by the four-probe technique. The conductivity of the PANI-MWCNT/PS composite film was affected both by the MWCNT concentration and polymerization time. In addition, DC electrical field was loaded during the oxidative polymerization to affect the distribution of the MWCNT included in the composite film, varying the loading voltage in the range of 0.1-3.0 V. The conductivity of the PANI-MWCNT/PS composite film was increased as loading voltage rose. However, this increase stops at a voltage higher than the critical value.

• 한국산업융합학회 논문집
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• 제25권5호
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• pp.899-908
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• 2022

In this study, a study was conducted to localize a large aluminum turbo fan used for tank powerpack. The turbo fan was scanned with a 3D scanner and then 3D modeling was performed. Computational fluid dynamics (CFD) were performed from the performance conditions of the fan, and structural analysis was performed using the pressure data obtained from CFD. The fan was reduced to 1/5 size by applying the geometric similarity. A 1/5 size fan has a honeycomb structure inserted into the front shroud and back shroud to reduce the weight by 5.3%. A 1/5 size fan was printed using a PBF 3D printer, and a 1/5 size fan with honeycombs was also printed. The pressure drop of 8.67 kPa and the required power of 138.19 kW, which satisfies the performance conditions of the fan, were confirmed from the results of CFD. The values of the maximum deformation amount of 0.000788 mm and the maximum effective stress of 0.241 MPa were confirmed from the structural analysis results. The fan printed by the PBF 3D printer had the same shape as the modeling, and the shape was perfect. There are no defects anywhere in appearance. However, the condition of the outer surface of the fan's back shroud is rough compared to other locations. The fan in which the honeycomb was inserted was also perfectly output, and the shape of the honeycomb was the same as the modeling.