This study intended to collect data for evaluating the meteorological value of Upo Wetland which is the largest wetland in the downstream of Nakdong River. The observations were conducted in summer at the Upo Wetland and its surrounding paddy field that is the converted areas from a wetland to a paddy field. The following results are obtained: 1) The temperature of Upo Wetland area was 1˚C lower than the surrounding area during the day while it was a little higher during the night.; 2) The maximum wind speed in the Upo Wetland area was 3.5 m/s which is stronger than 1.6 m/s of its surrounding area. The south wind was observed in the farmland for most of the day while north winds and south winds alternated between day and night in Upo Wetland.; 3) In heat budget analysis, Upo Wetland was wasted in the form of latent heat rather than sensible heat in daytime.

Mesoscale low is often observed over the downstream region of the East Sea (or, northwest coast off the Japan Islands) during East-Asia winter monsoon. The low system causes a heavy snowfall at the region. A series of numerical experiments were conducted with the aid of a regional model (MM5 ver. 3.5) to examine the formation mechanism of the mesoscale low. The following results were obtained: 1) A well-developed mesoscale low was simulated by the regional model under real topography, NCEP reanalysis, and OISST; 2) The mesoscale low was simulated under a zonally averaged SST without topography. This implies that the meridional gradient of SST is the main factor in the formation of a mesoscale low; 3) A thermal contrast (>10˚C) of land-sea and topography-induced disturbance served as the second important factor for the formation; 4) Paektu Mountain caused the surface wind to decelerate downstream, which created a more favorable environment for thermodynamic modification than that was found in a flat topography; and 5) The types of cumulus parameterizations did not affect the development of the mesoscale low.

잠열과 관련된 지표면 증발산량은 지표 온도를 결정하는 중요한 요인이며, 이를 정확히 산정하는 것은 중규모 순환장 예보의 정확도와 밀접하게 관련된다. 본 연구에서는 고해상도인 LANDSAT 5 TM 자료를 이용하여 대구광역시의 상대 증발산 효율을 추정하였다. 증발산 효율 추정은 복사 온도/식생 지수의 관계식을 이용하였다. 식생 지수는 대구광역시의 실제 토지 이용도와 일치하였다. 도시 지역내의 공원 지역의 경우 낮은 복사 온도를 나타내었다. 이것은 두류공원과 같은 도심내 공원 지역의 고증발산에 기인한 것이다. 그러나 전체적인 도심지는 저증발산이 두드러졌다. 그리고 지표면 구성특징에 의하여 도심지 내 공단 지역과 주거 지역은 상대적인 증발산 분포에서 차이가 나타났다.

본 연구는 21세기 기후변화에 대한 적응전략을 해수면 상승 관점에서 검토하였다. 해수면 상승에 취약한 것으로 알려진 연안역에 대한 적응책을 고려하는 경우 적응이 필요한 장소, 적응방법, 적응시기에 대한 검토가 필요하다. 연안역에 대한 적응 능력 평가는 영향 및 적응 잠재력에 대한 이해를 필요로 한다. 해수면 상승에 대한 적응방법에는 관리적 이주, 순응, 방어가 있으며, 이들의 적용에는 취약지대 토지이용 상황, 취약성 정도, 경제성 분석 등의 검토를 통한 대응 방안의 조합이 요구된다. 적응시기에 대하여는 예측적 적응과 반응적 적응으로 구분할 수가 있으며, 이들을 함께 고려하는 것이 효과적이다. 기후변화 대응은 과학적 불확실성 하에서 이루어지는 과정으로 대응정책 결정은 정보와 인식 구축, 계획 및 정책 구상, 실행, 모니터링 및 평가의 단계로 이루어져야 한다.

The concept of the satellite formation flight is area where it is actively study with expandability and safety compare to existing satellite. For execution of duty with more safety issue, it needs to consider hot topic of space debris for operation of formation flight. In this paper, it suggests heuristic algorithm to have avoidance maneuver for space debris towards operating flight formation. Indeed it covers, using common software, operating simulation to nearest space environment and not only to have goal of avoidance but also minimizing the usage of fuel and finding optimization for maximizing cycle of formation flight. For improvement on convergence speed of existing heuristic algorithm, it substitute to hybrid heuristic algorithm, PSOGSA, and the result of simulation, it represents the satisfaction of minimum range for successful avoidance maneuver and compare to not using avoidance maneuver, it keeps more than three times of formation maintenance performance. From these, it is meaningful results of showing several success goals like simple avoidance collision and fuel usage and decreasing number of times of maintaining formation maneuver.

Due to the continuous space development by mankind, the number of space objects including space debris in orbits around the Earth has increased, and accordingly, difficulties of space development and activities are expected in the near future. In this study, among the stages for space debris removal, the implementation of a vision-based approach technique for approaching space debris from a far-range rendezvous state to a proximity state, and the ground test performance results were described. For the vision-based object tracking, the CAM-shift algorithm with high speed and strong performance, and the Kalman filter were combined and utilized. For measuring the distance to a tracking object, a stereo camera was used. For the construction of a low-cost space environment simulation test bed, a sun simulator was used, and in the case of the platform for approaching, a two-dimensional mobile robot was used. The tracking status was examined while changing the position of the sun simulator, and the results indicated that the CAM-shift showed a tracking rate of about 87% and the relative distance could be measured down to 0.9 m. In addition, considerations for future space environment simulation tests were proposed.

In this paper, the authors introduced a new approach to find the optimal collision avoidance maneuver considering multi threatening objects within short period, while satisfying constraints on the fuel limit and the acceptable collision probability. A preliminary effort in applying a genetic algorithm (GA) to those kinds of problems has also been demon\-strated through a simulation study with a simple case problem and various fitness functions. And then, GA is applied to the complex case problem including multi-threatening objects. Two distinct collision avoidance maneuvers are dealt with: the first is in-track direction of collision avoidance maneuver. The second considers radial, in-track, cross-track direction maneuver. The results show that the first case violates the collision probability threshold, while the second case does not violate the threshold with satisfaction of all conditions. Various factors for analyzing and planning the optimal collision avoidance maneuver are also presented.

To prepare for a future Korean lunar orbiter mission, semi-optimal lunar capture orbits using finite thrust are designed and analyzed. Finite burn delta-V losses during lunar capture sequence are also analyzed by comparing those with values derived with impulsive thrusts in previous research. To design a hypothetical lunar capture sequence, two different intermediate capture orbits having orbital periods of about 12 hours and 3.5 hours are assumed, and final mission operation orbit around the Moon is assumed to be 100 km altitude with 90 degree of inclination. For the performance of the on-board thruster, three different performances (150 N with Isp of 200 seconds, 300 N with Isp of 250 seconds, 450 N with Isp of 300 seconds) are assumed, to provide a broad range of estimates of delta-V losses. As expected, it is found that the finite burn-arc sweeps almost symmetric orbital portions with respect to the perilune vector to minimize the delta-Vs required to achieve the final orbit. In addition, a difference of up to about 2% delta-V can occur during the lunar capture sequences with the use of assumed engine configurations, compared to scenarios with impulsive thrust. However, these delta-V losses will differ for every assumed lunar explorer's on-board thrust capability. Therefore, at the early stage of mission planning, careful consideration must be made while estimating mission budgets, particularly if the preliminary mission studies were assumed using impulsive thrust. The results provided in this paper are expected to lead to further progress in the design field of Korea’s lunar orbiter mission, particularly the lunar capture sequences using finite thrust.

다층 변위 매핑 기법은 여러 층으로 구성된 변위 맵들을 사용하여 단층의 변위 맵으로 표현할 수 없는 복잡한 형태를 재현할 수 있으며, 영화와 게임 등의 디지털 콘텐츠에서 보다 사실적인 표현을 저비용으로 제공할 수 있다. 하지만 다층 변위 맵 자료 구조의 특성상 표현을 자세히 할수록 여러 층의 변위 맵이 필요해지고 하단부의 변위 맵일수록 변위 정보를 저장하고 있지 않은 공간이 많이 생긴다. 본 논문에서는 저장 공간을 비효율적으로 사용하는 다층 변위맵을 비손실 압축하고 렌더링하는 방법을 제안한다. 제안하는 렌더링 방법은 비손실 압축 변위맵 정보를 사용하기 때문에 원본 변위 맵의 렌더링 결과와 동일한 화질을 보장한다.