• 한국항행학회논문지
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• 제26권4호
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• pp.195-204
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• 2022

본 논문에서는 경사 고각 발사 시스템에서 활용하기 위한 발사체 항법장치의 급속 초기정렬기법에 대해 다룬다. 급속초기정렬기법 중 하나인 원샷(One-shot) 정렬기법은 발사대에 장착된 항법장치의 정보를 활용하므로 수 초 내에 정렬이 가능하지만, 수직 발사체계에서만 적용되어 경사 고각에서의 성능이 검증되지 않았다. 따라서 본 논문에서는 원샷 정렬기법을 경사 고각 발사 시스템으로 적용 시 발생하는 오차 요소에 대해 분석하였고, 이를 최소화하여 정렬 성능을 개선하기 위한 방안을 소개하였다. 추가로, 제시한 원샷 정렬기법에 대해 성능시험을 수행함으로써, 실 항법장치를 운용하는 환경에서도 유효한 효과가 있음을 확인하였다.

• 한국자동차공학회논문집
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• 제19권5호
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• pp.82-91
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• 2011

In this paper, a planar model for mechanics of a vehicle/pedestrian collision incorporating road gradient is derived to evaluate the pre-collision speed of vehicle. It takes into account a few physical variables and parameters of popular wrap and forward projection collisions, which include horizontal distance traveled between primary and secondary impacts with the vehicle, launch angle, center-of-gravity height at launch, distance from launch to rest, pedestrian-ground drag factor, the pre-collision vehicle speed and road gradient. The model including road gradient is derived analytically for reconstruction of pedestrian collision accidents, and evaluates the vehicle speed from the pedestrian throw distance. The model coefficients have physical interpretations and are determined through direct calculation. This work shows that the road gradient has a significant effect on the evaluation of the vehicle speed and must be considered in accident cases with inclined road. In additions, foreign/domestic empirical cases and multibody dynamic simulation results are used to construct a least-squares fitted model that has the same structure of the analytical one that provides an estimate of the vehicle speed based on the pedestrian throw distance and the band within which the vehicle speed would be expected to be in 95% of cases.

• 한국항공우주학회지
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• 제45권11호
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• pp.914-921
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• 2017

우주발사체 고공환경모사의 실험적 연구는 우주발사체 발사 및 임무완수에 대한 독자적 기술력 확보를 위해 중요하다. 본 연구는 한국형발사체(Korean Space Launch Vehicle; KSLV-II)의 발사 후 마하수 6을 돌파하는 고도 65 km 조건을 선정하였다. 지상시험장비중 하나인 충격파 터널을 이용하여 고공환경모사를 수행하였다. 유동발달 이후 공기열역학적 특성과 수직 및 경사충격파 확인을 위해 선두부 모델의 정체 압력과 정체 열 유량, 그리고 반구형상 모델의 충격파 이탈거리 측정을 통해 유동검증을 수행하였다. 추가적으로 발사체 측면과 저부면 현상연구에 사용되는 시험모델의 자유류 회복을 위한 충격파 상쇄 기법을 개발 및 검증하였다. 세 가지 유동검증 결과를 통해 이론값과 약 ${\pm}3%$ 이내의 오차를 갖는 정확한 유동이 발달되었음을 확인하였다. 그리고 충격파 상쇄기법을 갖는 천이구간 축소 모델의 경사충격파 경사각과 수평 평판모델의 경사각, 그리고 모델 측면 정압력의 실험값과 이론값의 오차가 각각 2%, 그리고 1% 으로 확인되었으며, 이를 통해 해당 충격파 상쇄 기법의 합리적인 효과가 검증되었다.

• 한국추진공학회지
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• 제3권4호
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• pp.67-74
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• 1999

고체 물체 표면이나 지표면에 초음속 제트가 충돌할 때 발생되는 문제들은 다단 로켓의 분리, 우주공간에서의 도킹, 수직 이/착륙기, 제트 엔진의 배기가스, 가스터빈 블레이드, 지상 로켓 발사 등의 다양한 상황에서 일어나며 이러한 충돌제트의 유동은 아음속과 초음속 혼합영역, 충격파가 교차하는 영역, 팽창파, 난류 전단층 등의 매우 복잡한 구조를 이루고 있는 것으로 알려져 있다. 본 연구에서는 출구마하수 2, 축소-확대형 초음속 노즐을 통해 과소 팽창된 제트가 수직, 경사평판에 부딪힐 때 형성되는 표면압력분포 및 유동가시화 등을 초음속 유동시험장치를 이용하여 연구하였다. 평판에서의 최대압력은 수직일 경우보다 경사졌을 때 훨씬 더 컸으며, 이는 여러 충격파를 통한 압력 회복 때문이다. 또한, 평판이 자유제트의 첫 번째 충격파 셀 내에 위치할 때 과소 팽창비에 따른 표면압력분포는 서로 유사한 경향을 보여주었다.

• 한국군사과학기술학회지
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• 제5권2호
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• pp.37-49
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• 2002

In this paper, flyout stability of missile that is launched in inclined launcher using sabots is analyzed. To include missile bending motion during flyout, FEA model of missile is converted into eight concentrated mass and equivalent stiffness matrix. Six d.o.f ship motion that have influence on flyout stability is modeled and missile firing time is modeled as probability variable to take arbitrary ship attitude into account. Gap between missile and sabot is modeled as normal distribution probability variable and Monte Carlo simulation is performed. As results, the coriolis acceleration effects by ship motion are analyed and statistical results of missile pitch rate are shown.

• 한국군사과학기술학회지
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• 제23권5호
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• pp.459-465
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• 2020

In this paper, a compact antenna assembly for an amplitude comparison direction-finding(DF) method for a small flight vehicle is presented. Designed antenna assembly consists of four antennas and it is mounted on a radius of 1.45 λ_c where λ_c corresponds to the wavelength of the center frequency. To achieve compactness and robustness of the assembly, the elements are fed by end-launch feeding method and have modified aperture shapes of E- or H-sectoral horns. The feeding part consists of SMA connector, stepped impedance matching structure, and square waveguide of 0.6 λ_c × 0.6 λ_c. To achieve different main beam directions for every antenna which is required condition for amplitude comparison DF method, all apertures of the antennas are inclined and it makes the main beam direction of each antenna to top, bottom, left, and right with respect to the axis of the platform. To verify the validation of DF performance of the presented antenna assembly, amplitude comparison curves using measurement results are presented. The bandwidth of the antennas are above 3.2 % in Ku-band(VSWR ≤ 2:1).

• 우주기술과 응용
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• 제2권2호
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• pp.146-168
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• 2022

미·중간 패권경쟁과 최근 미·러간 동유럽(우크라이나)에서의 군사적 경쟁에서 증명한 것처럼, 대부분의 안보 전문가들은 21세기 미국의 가장 큰 안보위협은 강대국간 경쟁의 복원이라고 평가하고 있다. 상기 강대국간 패권경쟁의 핵심수단은 군사력이며, 이러한 군사력 운용의 효율과 효과성을 극대화하는 수단은 단연 우주력(space power)이다. 이를 반영하듯 최근 미국과 중·러간 우주패권경쟁이 전(全) 분야로 확대되고 있다. 상기한 전략환경하에서 우리나라도 우주에서의 국익을 보호하고 국민의 생명과 재산을 보호하기 위해 도약적인 국가 우주력 발전이 필요하다. 우리나라는 2021년 6월 한·미 미사일 지침 해제 및 한국의 '아르테미스' 프로젝트 참가 결정을 계기로 도약적 우주력 발전을 위한 계기가 마련되었다. 반면, 한반도의 지정학적 위치의 제한으로 현(現) '나로' 우주센터에서 우주 발사체를 활용하여 우주자산을 궤도에 올려놓는 것은 많은 제한사항이 존재한다. 발사방향 제한, 충분한 안전공간확보 불가 및 지원시설 구축 제한 등 선진국 우주센터와 비교해 많은 제한사항이 존재한다. 본고에서는 현(現) '나로' 우주센터 입지조건을 선진국 우주센터와 비교하고 제한사항을 식별하고, 이를 상쇄할 수 있는 국내 후보지를 제시하는 데 있다.

• 대한예방한의학회지
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• 제9권2호
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• pp.1-16
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• 2005

The present study is designed to provide basic data for the future health promotion projects to be aimed at improving quality of life for the elderly people in the increasingly aging society of Korea by investigating factors related to the yangseng of old people in rural areas. The results of this study are intended to serve as fundamental for efficient approach toward health promotion projects for the elderly in rural communities. For this purpose, a survey by questionnaires was conducted to rural inhabitants from May to June 2004. The replies were analyzed from the perspective of Oriental medicine for yangseng. 1. The average points of health care appeared to be 3.24. In details by sub-areas, morality was 3.79, followed by 3.74 for activities and rest, 3.73 for sleeping, 3.29 for diet, 3.25 for mind, 2.88 for season, 2.12 for exercise and 1.95 for sexual life in sequence, showing that the yangseng of morality was scored highest while the area of sexual life were rated lowest. 2. As for the extent of health care depending on the characters of the subjects, spoused ones, married couples living alone, while the higher educated and the more leisure is utilized, the more the care is paid for yangseng. 3. Concerning the extent of yangseng depending on the general characters of the subjects, men showed more yangseng in activities and rest. The group aged 70 to 74 acquired the highest points in mind yangseng. The group with spouse featured higher concern for yangseng in the categories of morality, diet, activities and rest, sleeping and sexual life. Married couples who are living with no other family members recorded the highest points in the areas of morality, diet, sleeping and sexual life(P<0.05). 4. In terms of socioeconomic characters, the more one is educated, the more he/she is tended to take yangseng in the exercise, sleeping and sexual life. The group with occupation is inclined to take more yangseng in the activities and rest and sleeping. When people have to work for their keep, they usually showed to have highest yangseng for sleeping. People who enjoy leisure showed higher yangseng in all areas except for morality. In case man has religion, he showed more yangseng in the activities and rest, exercise and sleeping(P<0.05). 5. Those who reply they are confident with health showed higher yangseng. No significant difference was found in all areas except for sexual life in which high care is taken for yangseng, as far as one has no disease. Those who are confident with health had highest yangseng in all areas except for season yangseng(P<0.05). As seen above, extents of yangseng by the old people in the rural area are found to have difference depending on the individual and socioeconomic characters, factors which should be seriously considered in the local health promotion projects and projects for the health of the elderly. Particularly important is to launch health promotion programs and to analyze their effects to promote health care particularly in the areas of sexual life, exercise and season yangseng that turned out to be lowest by taking into account of yangseng in each sub-area.

• 대한의료기공학회지
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• 제8권1호
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• pp.96-114
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• 2005

This study was carried out to provide essential data for the future health promotion projects to be aimed at improving quality of life for the elderly people in the increasingly aging society of Korea by investigating factors related to the yangseng of old people in urban areas. The results of this study are to be used as basis for efficient approach toward health promotion projects for the elderly in urban communities. For the purpose, a survey by questionnaires was conducted to urbanites from May th June 2004. The collected replies were analyzed from the viewpoints of Oriental Medicine for yangseng. 1. The average points of health care were 3.24. In details by sub-areas, 3.78 was rated for morality yangseng, 3.29 for mind, 3.30 for diet, 3.79 for activity and rest, 2.32 for exercise, 3.72 for sleeping, 2.95 for season and 1.81 for sexual life, which showed that the area of activity and rest yangseng was scored highest while the area of sexual life yangseng was rated lowest. 2. As for the extent of health care depending on the characters of subjects, higher scores were rated by men than women, younger ones than aged and spoused ones than singles. Married couples living without other family members were found to yangseng most, while more yangseng was taken by the educated, job holders and those who utilize leisure and have religion in order. 3. Men exercised more yangseng than women in the diet, exercise and sleeping. By age, the group aged 65 to 69, the more yangseng in the exercise and sexual life. The group with spouse featured higher concern for yangseng in all categories except for season. Married couples who are living with no other family members recorded the highest point in all areas except for exercise. 4. The more one is educated, the more he/she is tended to take yangseng in the sub-areas of exercise and sexual life. The group with occupation is also inclined to take more yangseng in the same sub-areas as those of the highly educated. When they pay living cost together with offspring, they appeared to be the most yangseng in season and sexual life. People who enjoy leisure showed higher yangseng in all areas except for season. Religion had a significant influence in all areas except for activity and rest yangseng. 5. Those who reply that they are confident with health and have no disease proved to have higher yangseng. Depending on whether one has disease or not, higher yangseng was confirmed in such sub-categories as mind and sleeping. Those who replied they are confident with health had higher yangseng in all areas except for season. As seen above, yangseng of the old people in the urban area is found to have different extent depending on the individual and socioeconomic characters, factors which should be seriously considered in the local health promotion projects and projects for the health of the elderly. It seems therefore necessary to launch health promotion programs and to analyze their effects to promote health care particularly in the areas of sexual life, exercise and season yangseng that featured lowest grade of yangseng in each sub-area.