• 한국항공우주학회지
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• 제45권11호
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• pp.922-931
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• 2017

본 논문에서는 신규 방식의 발사관 덮개인 분리식 덮개의 설계과정과 해석 및 실험적 검증결과에 대하여 기술하였다. 발사관 덮개에 보편적으로 사용되고 있는 종래의 파열식 및 구동기 방식의 덮개의 단점을 극복하기 위하여 폭발볼트 및 스프링 레버를 이용한 분리식 덮개를 제안하였다. 분리식 덮개는 폭발볼트와 스프링 레버 구동시스템으로 단순하게 구성되어 있다. 첫 번째로, 수학적 모델에 의해 제시된 설계제원에 대하여 다물체 동역학 해석을 통하여 기계적 작동성능에 관한 검토를 실시하였다. 도출된 해석결과는 이후 초고속 카메라로 획득한 계측 결과와 잘 부합하였다. 또한 작동성능에 대한 설계인자별 영향을 파악하기 위한 경향분석이 수행되었다. 본 연구를 통해 구조적 단순성과 가격의 효율성을 보유한 신규방식의 발사관 덮개를 군수분야에 제시하는데 기여했다고 판단되며 특별히 다연장 발사관 시스템(MLRS)에 유용하게 적용될 것이라고 예상된다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제3권2호
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• pp.163-171
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• 1996

Observing that a locally weakly Lindel$\"{o}$f space is a quasi-F space if and only if it has an F-base, we show that every dense weakly Lindel$\"{o}$f subspace of an almost-p-space is C-embedded, every locally weakly Lindel$\"{o}$f space with a cocompact F-base is a locally compact and quasi-F space and that if Y is a dense weakly Lindel$\"{o}$f subspace of X which has a cocompact F-base, then $\beta$Y and X are homeomorphic. We also show that for any a separating nest generated intersection ring F on a space X, there is a separating nest generated intersection ring g on $\phi_{Y}^{-1}$(X) such that QF(w(X, F)) and ($\phi_{Y}^{-1}$(X),g) are homeomorphic and $\phi_{Y}_{x}$(g$^#$)=F$^#$.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.103-106
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• 2009

Fracture characteristics of plate shape using shock tube for glass filled ceramics was carried out. Glass filled ceramics have been considered as a promising candidate material for the dome port cover of air breathing engine. This part of the air breathing engine has an important role separating solid and liquid fuel, and needs the frangible characteristics that the fracture of a part should not affect the internal components of combustion. The objectives of this study are to evaluate the fracture pressures for various thicknesses and diameters of shock impact area. Also fracture phenomena of separated membrane using a shock tube are observed. The experimental apparatus of shock tube consists of a driver, a driven section and a dump tank. The used material is glass filled ceramic made from Corning company. Specimens are used 3, 4.5 and 6mm thickness. Also diameters of shock wave area are chosen 70, 60 and 50 mm. It is expected that the results obtained from this study can be used in the basic data for the dome port cover design of an air breathing engine.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.338-343
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• 2008

Fracture characteristics of plates and dome shapes for machinable glass ceramics using compressed shock wave. Machinable glass ceramics have been considered as a promising candidate material for the dome port cover of air breathing engine. This part of the air breathing engine has an important role separating solid and liquid fuel, and needs the frangible characteristics whereby the fracture of a part should not affect the internal components of combustion. The objective of this study are to evaluate the fracture pressure and phenomena of separated membrane using a shock tunnel. The experimental apparatus consists of driver, a driven section and a dump tank. The used material is machinable glass ceramic from Corning company. Specimens are used 3, 4.5 and 6mm thickness with plates and dome shapes. It is expected that the results obtained from this study can be used in the basic data for the dome port cover design of an air breathing engine.

• 한국지리정보학회지
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• 제24권2호
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• pp.52-63
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• 2021

기존 연구에서는 연안습지를 탐지하기 위해 위성/항공 영상의 다중분광 밴드로부터 산출한 식생지수 또는 토지피복도를 활용하였으나, 단일 센서만을 활용할 경우 토지피복정보와 지형정보를 동시에 고려하는 것에 한계가 있어 높은 정확도의 연안습지 탐지 및 대규모 연안습지 관리 업무 수행에 많은 지장을 초래하였다. 본 연구에서는 우리나라 서해안 곰소만 지역을 촬영한 Sentinel-2 위성영상의 다중분광 밴드와 디지털 지형 모델인 SRTM(Shuttle Radar Topography Mission) DEM(Digital Elevation Model)을 사용하여 서해안 곰소만의 대규모 연안습지를 다음의 과정을 통해 탐지하였다. 우선 Sentinel-2 위성영상의 Green 및 근적외선 밴드를 활용하여 정규수분지수 영상을 제작하였다. 그리고 정규수분지수 영상에서 픽셀의 밝기값 0.2를 임계치로 설정하여 물과 육지를 구분하는 이진화 영상을 제작하였으며, SRTM DEM에서 픽셀의 밝기값 0을 임계치로 설정하여 해수면 아래와 해수면 위를 구분하는 이진화 영상을 제작하였다. 최종적으로는 두 장의 이진화 영상에 중첩 분석을 적용하여 이진화 영상 기반 연안습지 지도를 제작하였다. 본 연구에서 제안한 기술을 활용하여 제작한 이진화 영상 기반 연안습지 지도의 정확도는 94%로서 매우 높은 결과를 보여주었으며, 연안습지가 아닌 내륙습지, 산지습지 등은 탐지되지 않아서 연안습지 관리 업무에 매우 효과적으로 활용될 수 있음을 확인하였다.

• 한국정보전자통신기술학회논문지
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• 제14권2호
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• pp.109-114
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• 2021

네트워크 환경에서 다양한 사용자가 증가하면서 송수신되는 민감한 비밀 정보를 공격자로부터 보호하는 것은 어렵다. 이미지에 비트화된 비밀 자료를 LSB 기법으로 은닉하는 것은 공격에 매우 취약할 수 있다. 이를 해결하기 위해 암호화와 정보은닉이 결합하는 하이브리드 방법이 활용된다. 이용자가 비밀 메시지를 안전하게 보호하고, 비밀 통신을 구현하기 위한 효과적인 방법이 요구되고 있다. 즉, 이미지 품질을 보장하기 위해 보안성과 인식 불가능성을 향상시키기 위한 새로운 접근법이 필요하다. 이 논문에서 MSB와 LSB를 기반하여 커버 이미지에 한글 메시지를 은닉하는 LSB 스테가노 그래피 기법을 제안한다. 이때 한글을 초성, 중성, 종성으로 분리한 후, 비밀 자료는 선택된 MSB에 따라 Exclusive-OR 혹은 Exclusive-NOR 연산을 적용한다. 또한 계산된 비밀 자료는 피보나치 기법에 의해 변환된 커버 이미지의 LSB n개 비트에 은닉한다. 적용된 결과의 효율성을 확인하기 위해 PSNR을 이용하였다. 허용되는 결과로서 적합한 41.517(dB)가 확인되었다.

• 한국농공학회논문집
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• 제53권6호
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• pp.145-152
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• 2011

In order to heat greenhouse nearby river channel, riverbank filtration water source heat pump was developed for getting plenty of heat flux from geothermal energy. Recharging well, thermal storage tank with separating insulation plate and filtering tank for eliminating iron, manganese were mainly developed for making the coefficient of performance (COP) of heat pump higher. Heating system using riverbank filtration water source heat pump was installed at a paprika greenhouse in the Jinju region where a single fold of vinyl cover and 2 layers of horizontal thermal curtain were installed as a part of temperature keeping and heat insulation with a greenhouse area of 3,185 $m^2$. 320,000 kcal/h was supplied for performing a site application tests. A greenhouse heating test was performed from Feb. 1, 2011 to Apr. 30, 2011. As the result of that, COPh of the heat pump was measured in the range of 4.0~4.5, while COPS of the system was represented as 2.9~3.3. COP measured of the heat pump was very good and well responded to indoor heating temperature of the environment control system of a greenhouse.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1424-1429
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• 2004

Distillation is one of many processes that can be used for the purification of water. It requires an energy input such as heat and solar radiation is a possible source of energy. In this process, water is evaporated, thus separating water vapor from the solute. The vapor is then condensed to pure water. The temperature of the water, the cavity of the enclosure and the surface of the glass was measured everyday. Fifteen points were chosen for the temperature measure using a thermocouple. The inner wall and the bottom of each still was painted black for good absorption of heat. The enforced glass was used for the cover for the entering of solar energy. The size of all of the water baths was the same, but the glass of the rectangular form had a tilted angle. In the case of fine or general weather, the volume of condensed water produced by $45^{\circ}$ and $60^{\circ}$ is very irregular compared to that of $15^{\circ}$ and $30^{\circ}$, In case of a rainy day, the occurrence of the volume of condensed water was similar to that of $15^{\circ}$ and $30^{\circ}$, but the volume of condensed water produced by $30^{\circ}$ was the highest.

• 한국군사과학기술학회지
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• 제18권4호
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• pp.350-357
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• 2015

Many countries have been developing and operating an underwater surveillance system in order to protect their oceanic environment from infiltrating hostile marine forces which intend to lay mines, conduct reconnaissance and destroy friendly ships anchored at the harbor. One of the most efficient methods to detect unidentified submarine approaching harbor is sensing variation of magnetism of target by magnetic sensors. This measurement system has an advantage of high possibility of detection and low probability of false alarm, compared to acoustic sensors, although it has relatively decreased detection range. The contents of this paper mainly cover the analysis of possible effectiveness of magnetic sensors. First of all, environmental characteristics of surveillance area and magnetic information of simulated targets has been analyzed. Subsequently, a signal processing method of separating target from geomagnetic field and methods of estimating target location has been proposed.

• Archives of Plastic Surgery
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• 제48권4호
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• pp.378-383
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• 2021

Conjoined twins are rare, and each set of conjoined twins has a unique conjoined anatomy. It is necessary to perform separation to increase the chance of patient survival. Tissue expansion is an advanced technique for providing sufficient soft tissue and skin for wound closure. We report the successful application of rapid tissue expansion in 10-month-old xipho-omphalopagus conjoined twins in Vietnam. A tissue expander was placed on the anterior body between the sternum and umbilicus with a baseline of 70 mL sterile saline (0.9% NaCl). The first injection into the tissue expander began on the 6th day after expander insertion, and injections continued every 2 days with approximately 30-70 mL per injection according to the expansion of the skin. The expander reached 335 mL after six injections and within 10 days. In order to prepare for surgical separation, expansion was completed on the 15th day after insertion. The expanded skin area was estimated to be 180 cm², which was sufficient to cover both patients' skin deficiencies. The twins presented for surgical separation 6 days following the completion of tissue expansion. Both babies were discharged in good health 1 month after separation.