전단변형 효과를 무시하는 경우에 보존력을 받는 박벽공간뼈대구조의 자유진동 및 안정성해석을 위한 일반이론을 유도한다. 이를 위하여 비대칭 박벽단면의 임의점을 통과하는 부재축과 이와 직각을 이루는 두 개의 좌표축을 도입하여 직각좌표계를 정의하고, 이 좌표축을 기준으로 semitangential 회전의 2차항을 고려하는 변위장을 도입하여 연속체에 대한 가상일의 원리로 부터 운동에너지, 탄성변형에너지, 그리고 초기응력에 의한 포텐셜에너지를 유도한다. 이를 이용하여 선형분포하중을 받는 박벽공간뼈대구조의 자유진동 및 안정성해석을 위한 운동방정식을 제시한다. 3차 Hermitian 다항식을 변위파라미터의 형상함수로 사용하여 박벽공간뼈대부재의 질량, 탄성강성 및 기하학적 강성행렬을 산정할 뿐만 아니라, 임의의 위치에 작용하는 분포하중에 대한 하중보정강성행렬(load-correction stiffness matrix)을 제시한다. 본 이론 및 방법의 타당성을 검증하기 위하여 수치해석을 수행하고 문헌의 결과와 비교하여 정당성을 입증한다.

공간뼈대의 구조에 대하여 기하학적 비선형성이 고려될 수 있는 유한요소이론 및 해석법을 제시한다. 이를 위하여 가상일의 원리를 이용하여 대변형효과를 고려한 3차원 연소체의 평형방정식으로부터, 구속된(restrained warping)효과를 무시하고 유한한 회전각의 2차항의 효과를 포함하는 변위장을 도입하여 초기응력을 받는 공간뼈대요소의 증분평형방정식을 유도한다. 공간뼈대구조를 유한요소로 나누어 요소의 변위장을 요소변위 벡터에 관한 Hermitian다항식으로 나타내고 이를 평형방정식에 대입함으로써 탄성 및 가하학적인 강도행렬을 유도한다. 또한 updated Lagrangian co-rotational formulation에 근거하여, 증분변위로부터 강체회전변위와 순수변형성분을 분리시켜서 강체회전은 요소의 방향변화를 결정하고, 순수변형은 부재력증분을 산정하는 불평형하중 산정법을 제시한다. 공간뼈대구조의 횡-비틂좌굴 및 후좌굴 거동에 대한 예제들을 통하여 본 연구에 대한 해석결과와 문헌의 결과를 비교 검토함으로써 본 연구에서 제시된 이론 및 해석방법의 정당성을 입증한다.

The Purpose of this study was to establish the belter residential environment in Apt. complex. In this study, the management consciousness of exterior space and the degree of satisfaction were investigated and analyzed on the GI-SAN Apt. complex in Taegu city. The data were obtained through the questionnaire survey about the exterior space of Apt. complex and analyzed by the SPSS/PC. The results of this analysis are as follow; The result of the image analysis were the cleanness factor and the arrangement factor, which have great influenced in residents image of exterior space. The dissatisfaction source of the management conditions were owing to the lake of management techniques and the discord of residents. The subject of management in the residents consciousness was the management office. In additionally, the management form by the residents were highly showed the cleaning and weeding. The main issues of their dissatisfaction about the exterior space was the lake of size, quantity of plants and rest space. The place of the most demand on management was investigated the children playground which was regarded to be the most damaged.

In this work, preliminary launch opportunities from NARO Space Center to the Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points, L1 and L2 points are selected as suitable candidates for, respectively, solar and astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting problem is formulated regarding the location of NARO Space Center and relevant Target Interface Point (TIP) for each different launch date is derived including launch injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more than one year of mission orbit around the Lagrange points, is also derived as an example. Even the current work has been made under many assumptions as there are no specific mission goals currently defined yet, so results from the current work could be a good starting point to extend diversities of future Korean deep-space missions.

The Korean Institute of Technology Satellite (KITSAT-1) is the first satellite developed by the Satellite Technology Research Center and the University of Surrey. KITSAT-1 is orbiting the Earth’s orbit as space debris with a 1,320 km altitude after the planned mission. Due to its relatively small size and altitude, tracking the KITSAT-1 was a difficult task. In this research, we analyzed the tracking results of KITSAT-1 for one year using the Midland Space Radar (MSR) in Texas and the Poker Flat Incoherent Scatter Radar (PFISR) in Alaska operated by LeoLabs, Inc. The tracking results were analyzed on a weekly basis for MSR and PFISR. The observation was conducted by using both stations at an average frequency of 10 times per week. The overall corrected range measurements for MSR and PFISR by LeoLabs were under 50 m and 25 m, respectively. The ionospheric delay, the dominant error source, was confirmed with the International Reference of Ionosphere-16 model and Global Navigation Satellite System data. The weekly basis orbit determination results were compared with two-line element data. The comparison results were used to confirm the orbital consistency of the estimated orbits.

This paper presents at the characteristics of publications in the Journal of Astronomy and Space Sciences from 1984 to 2018. Since its first publication, a total of 1,113 papers (~35 volumes) have been published up to December 2018. While the space astronomy field has made up a large portion of the total number of papers, the number of annually published papers in this field is decreasing. In contrast, the number of papers in the space environment field has been showing an increasing trend since 2013, accounting for more than 30% of the annual publications. The participation rate of foreign researchers has been maintained at greater than 20% since 2012. Despite the decrease in the number of paper per year, there are positive developments including sustained foreign researcher participation at greater than 20% and improvements in the impact factor. We believe that JASS has the potential to enter the distinguished level of international academic journals following a welldeveloped future road map.

With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a 1-m2 radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.

게임플레이어는 게임레벨의 목표에 따라 구성된 플레이공간에서 레벨디자이너가 설정한 게임 플레이를 경험한다. 플레이어의 경험적 행동들은 게임레벨 공간구조와 구조물 배치에 영향을 받는다. 따라서 게임레벨디자인 초기단계에서 게임레벨의 공간구조를 파악하고 분석하는 것은 중요한 과정이다. 본 논문은 공간이론을 바탕으로 FPS게임레벨의 공간구조 및 구성요소를 파악 하였다. 3종의 FPS게임에서 게임레벨 204개를 대상으로 관찰실험을 진행하고 게임레벨 목표에 따른 공간 구성요소 분포의 차이를 확인하였다. 분석결과, 게임레벨의 목표에 따라 플레이공간 에서의 경험적 행동은 뚜렷한 차이를 보이며 이것을 유도하는 공간구조는 차별성을 가진다.

To create urban landscapes that take human emotion into consideration, the present study verified the psychological effects of artificial waterscape facilities on users, as these facilities significantly impact their psychological comfort. Data was collected using the SD scales and POMS of 60 male and 60 female participants after they watched a video of four waterscape facilities. Participants deemed the video clip of a fountain waterscape to be artificial and linked it with changeable images that increased their vigor. The video clip of waterfall stimulated various impressions (e.g., vital, liked, active, etc.) and changed participant’ mood states by increasing their vigor and decreasing fatigue. The video clip of the pond yielded familiar impressions, produced less free images, and decreased tension among participants. Finally, the video clip of the stream stimulated quiet and comfortable images as well as reduced negative feelings of anger, confusion, and depression among participants. Furthermore, males experienced more positive effects than females, regardless of the type of waterscape facility. The study findings indicate that the four different waterscape facilities influenced participants’ mood states. Additionally, the psychological effects differed by gender. The data suggest that landscape planners need to carefully consider their choice of waterscape facility when designing green spaces to ensure that the space is psychologically comforting to users.

This study surveyed the human thermal responses according to the green space types. Three green space type (forest trail, residential area and central building district) were set the research sites in Dongdaemun-gu, Seoul. The physical thermal environment factors were measured while the human thermal responses were investigated. The air temperature and radiant temperature showed higher in central building area where sky view factor was 0.799 than in forest trail where sky view factor was 0.651. The skin temperatures increased according to green space type and rectal temperatures showed the highest value in central building area. The thermal sensation vote and thermal comfort showed the differences only between forest trail and central building area. These results will use as base line data on the green space type management plan for thermal environment amenity.

This study tried to compare and analyze the thermal comfort index according to GVZ of school green space. For the analysis, this study performed a correlation analysis with weather elements by measuring and calculating UTCI, PMV, and WBGT according to GVZ. GVZ was in the order of Type 3 (5.68 m3/m2) > Type 2 (4.71 m3/m2) > Type 1 (3.37 m3/m2). The average temperature and solar radiation, surface temperature, globe temperature among weather characteristics was in the order of Type 1> Type 2 > Type 3. The UTCI in the school green space was in the order of Type 1 (33.95°C) > Type 2 (33.68°C) > Type 3 (32.73°C). At Type 3 that the GVZ is higher than other Types, it is belongs to range of 26~33°C which gets normal heat stress, and other Types belong to range of 33~38°C which gets strong heat stress. The PMV was in the order of Type 1 > Type 2 > Type 3, and the estimated rate of unsatisfaction was appeared as 100%, so it is uncomfortable even in the school green space that it requires measure on heat wave. The WBGT was in the order of Type 1 > Type 2 > Type 3. The result of the correlation analysis according to the heat comfort index shows that, the higher the green ratio and GVZ are, the UTCI has negative relationship, and PMV and WBGT were analyzed as have no relationship according to green characteristics, but this result was considered as measured at green space when the temperature was at its highest so the uncomfortable feeling was also highest. The result of correlation analysis of green characteristics and the weather elements shows that GVZ and insolation, temperature has negative relationship, so it is considered that the higher the GVZ is, the solar radiation and the temperature are decreased.

본 연구에서는 대공간에서의 연기유동을 해석하기 위한 방안으로 전산유체역학을 바탕으로 하는 수치해석 기법을 적용하였으며, 구체적으로는 정확성과 타당성이 검증되어 열·유동 해석문제에 널리 적용되고 있는 3차원 범용프로그램인 CFX14를 사용하였다. 수치해석 대상은 스페인에서 수행된 Murcia Atrium Fire Tests의 대공간을 선정하였다. 대상 대공간은 19.5 m × 19.5m × 20.0m 의 전체적인 크기를 갖는다. 천장에는 4개의 배연 송풍기가 설치되어 있고, 벽의 하단부에 8개의 그릴형 흡입구가 설치되어 있다. 수치해석 조건은 상기의 실규모 실험 Test 1과 동일하게 열방출율과 흡입구의 개방방식 조건을 적용하였다. 열방출율이 1.35 MW이고 흡입구는 모두 개방하는 조건이 적용되었다. 한편 배연용 송풍기는 모든 송풍기가 가동되는 조건이며 기준온도는 실험시의 외부기온이 적용되었다. 수치해석 결과에 대한 분석은 다음과 같다. 우선 수치해석 대상 대공간의 중앙 단면에서의 시간별 온도분포를 살펴보면 중앙 화염원에서 고온의 연기가 생성되어 천장까지 상승해서 천장의 배기구로 배출되며 일부는 천장을 타가 측면으로 퍼져서 벽면을 타고 아래로 하강하는 것을 알 수 있다. 시간이 지나면서 차차 연기가 공간의 상층부에 축적되고 일부는 하층부로 하강하면서 전체적인 공간내 온도가 상승하는 것을 알 수 있다. 실규모 실험과 수치해석의 결과를 비교하여 분석해 보면 실규모 실험과 수치해석 결과가 비교적 유사한 추이를 보이고 있으며, 이로부터 본 연구에서 설정한 수치해석 방안이 대공간 건축물의 연기유동 해석과 효과적인 연기제어 시스템 개발에 적용될 수 있을 것으로 판단된다.

We have designed a 30 cm cryogenic space infrared telescope for astronomical observation. The telescope is designed to observe in the wavelength range of 0.5~2.1 μm, when it is cooled down to 77 K. The result of the preliminary design of the support structure and support method of the mirror of a 30 cm cryogenic space infrared telescope is shown in this paper. As a Cassegrain prescription, the optical system of a 30 cm cryogenic space infrared telescope has a focal ratio of f/3.1 with a 300 mm primary mirror (M-1) and 113 mm secondary mirror (M-2). The material of the whole structure including mirrors is aluminum alloy (Al6061-T6). Flexures that can withstand random vibration were designed, and it was validated through opto-mechanical analysis that both primary and secondary mirrors, which are assembled in the support structure, meet the requirement of root mean square wavefront error <λ/8 for all gravity direction. Additionally, when the M-1 and flexures are assembled by bolts, the effect of thermal stress occurring from a stainless steel bolt when cooled and bolt torque on the M-1 was analyzed.

We conducted thermal analyses and cooling tests of the space observation camera (SOC) of the multi-purpose infrared imaging system (MIRIS) to verify passive cooling. The thermal analyses were conducted with NX 7.0 TMG for two cases of attitude of the MIRIS: for the worst hot case and normal case. Through the thermal analyses of the flight model, it was found that even in the worst case the telescope could be cooled to less than 206°K. This is similar to the results of the passive cooling test (~200.2°K). For the normal attitude case of the analysis, on the other hand, the SOC telescope was cooled to about 160°K in 10 days. Based on the results of these analyses and the test, it was determined that the telescope of the MIRIS SOC could be successfully cooled to below 200°K with passive cooling. The SOC is, therefore, expected to have optimal performance under cooled conditions in orbit.

최근 기후변화의 영향에 따른 대형화된 폭우로 인해 도시홍수 및 산사태가 발생하여 많은 인명과 재산피해가 발생하고 있다. 이러한 폭우재해에 대한 기존의 대응에는 하천, 하수도 등 전통적인 방재시설이 중요한 역할을 해왔으나, 기존의 방재시설만으로 도시 전체의 방재성능을 향상시키는 것은 경제적, 도시 환경적, 물리적으로 한계에 이르게 되었다. 따라서 도시전체의 재해영향을 비방재적 도시계획시설에 부분적으로 부담시켜 경제적이고 효과적인 도시방재가 이루어지도록 해야 할 필요성이 대두되었다. 특히 서울의 경우 공원녹지면적은 177.78㎢로 서울 전체면적의 29.37%에 이르고 있으므로 이를 지역적 방재성능 향상에 활용한다면 대형 방재시설 이상의 재해저감적응 효과를 발휘할 수 있을 것으로 예상된다. 따라서 생태저류 등과 같이 공원녹지에 유출저감기능을 부가시켜 일정용량의 재해방지역할을 수행하도록 하는 새로운 도시방재수법의 도입이 필요하다. 또한 도시를 실질적으로 폭우재해에 안전한 도시로 조성하기 위해서는 법제도 정비를 통해 그 기반을 확립해야 한다. 특히 도시계획시설인 공원녹지는 법제도 기반위에 결정되고, 설치되기 때문에 그 필요성이 크다. 따라서 본 연구에서는 폭우재해 저감적응을 위한 공원녹지 관련 법제도 개선 방안을 마련하고자 한다. 이를 위해, 국내외의 공원녹지 계획 및 설계와 관련된 법제도의 검토 및 비교분석을 통해 국내 법제도의 문제점을 도출하였다. 그리고 국외의 선진사례의 적용을 통한 국내의 폭우재해 저감적응을 위한 공원녹지 관련 법제도의 개선 방안을 마련하였다. 본 연구의 결과는 기후변화 및 방재적 측면을 강화하기 위한 도시계획 관련 법제도의 개선 자료로 활용 가능하며, 도시홍수의 대비 등 재해관련 정책 참고자료로 활용이 가능하다.

This study has intended to evaluate rural subjective landscape through participation of residents and visitors according to space types, and to perform comparative analysis of evaluation results between residents and visitors. This study has employed a survey method for which 58 residents of 8 villages within Seondong region at Gochang-gun and 70 visitors to Green Barley Field Festival in the target region have participated. 42 landscape view points were selected according to landscape scopes and space types, and then the preference was evaluated using landscape adjectives after showing pictures already taken for each landscape view point. This study has found the following results. First, whereas residents gave high points to natural landscape and artificial one at the historical culture areas in comparison with other landscape scopes, visitors gave them low points on the other hand. Second, visitors evaluated the cultivated area among space types of mixed landscapes with high value. Third, based on t-test for comparative analysis, the statistically significant differences of evaluation results appeared at 6 places among 8 natural landscapes, 3 places among 12 artificial landscapes, and 3 places among mixed landscapes.

본 연구는 소셜네트워크와 활발하게 연계되고 있는 스마트폰 플랫폼을 기반으로 한 농장경영 게임의 특성을 파악하기 위하여, 게임 내의 소셜 네트워크 플레이 경험이 스마트폰 플랫폼에서 보여지는 농장경영게임의 공간과 어떻게 연관되는가를 분석하고자 하였다. 스마트폰 플랫폼을 기반으로 한 SNS 농장경영게임의 플레이 경험은 주로 세 개의 모듈, 정작 모듈, 환경 배치 모듈, 공간 확장 모듈을 중심으로 이루어진다. 본 연구에서는 농장경영게임의 특성을 분석하기 위하여 공간경험이론을 바탕으로 외적 투시공간, 내부조망 공간, 상징적 기획 공간으로 나누어 각 공간에서 일어나는 플레이 경험을 중심으로 살펴보았다. 농장경영게임에서 플레이어는 고정된 시정을 통해 공간을 인식하고, 모듈을 재해석하여 재배치하는 데 있어 자신의 공간을 소셜 네트워크의 기본단위로 삼게 된다. 이러한 과정에서 공간은 단순한 배정이 아닌, 소셜 네트워크 게임에서 필수적인 협력 플레이를 일으키도록 하는 주체적 역할을 수행한다.