• 대한건축학회논문집:계획계
• /
• 제36권4호
• /
• pp.23-29
• /
• 2020

The latest urban planning is taking advantage of the city's spatiality, and its weight is increasing. The spatiality of the city extends to the three-dimensional air space, including the underground space and the surface space, and this is the relative location of land-use situations utilizing the characteristics of the feng shui geography. In this study, the urban planning of the Suwon Department and the construction process of the Suwon Hwaseong Fortress were analyzed based on the feng shui geography, using the topography and geographical features of Paldal Mountain as the center of the data. Natural-friendly urban planning is required to adapt to natural laws and to preserve and share the ecosystem while harmonizing with the surrounding environment.

• Nuclear Engineering and Technology
• /
• 제45권5호
• /
• pp.613-624
• /
• 2013

Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.

• International Journal of Aeronautical and Space Sciences
• /
• 제17권2호
• /
• pp.204-213
• /
• 2016

A differential game theory based approach is used to develop an automated maneuver generation algorithm for Within Visual Range (WVR) air-to-air combat of unmanned combat aerial vehicles (UCAVs). The algorithm follows hierarchical decisionmaking structure and performs scoring function matrix calculation based on differential game theory to find the optimal maneuvers against dynamic and challenging combat situation. The score, implying how much air superiority the UCAV has, is computed from the predicted relative geometry, relative distance and velocity of two aircrafts. Security strategy is applied at the decision-making step. Additionally, a barrier function is implemented to keep the airplanes above the altitude lower bound. To shorten the simulation time to make the algorithm more real-time, a moving horizon method is implemented. An F-16 pseudo 6-DOF model is used for realistic simulation. The combat maneuver generation algorithm is verified through three dimensional simulations.

• 설비공학논문집
• /
• 제6권4호
• /
• pp.337-343
• /
• 1994

Numerical analysis was applied to a simplified two-dimensional Ondol heating model which consists of heating space on the top of it along with radiant and convective heating floor panel, flue channel in the midway and rectangular underground soil region at the bottom. These three components constitute a system thermally coupled at the top and bottom interfaces of the flue channel. Investigated in the present paper are effects with variations of the Reynolds numbers of 100, 200, and 300, Grashof numbers of $0.1{\times}10^6$ and $0.3{\times}10^6$ and aspect ratios of 15 and 20 on the heat transfer and fluid flow characteristics of two-dimensional Ondol heating model by computer simulation.

• 한국항공우주학회지
• /
• 제35권6호
• /
• pp.474-482
• /
• 2007

초음속 공중발사 로켓의 모선분리에 대한 유동해석을 수행하였다. 전기체 형상의 모선(F-4E Phantom)에서 분리되는 로켓주변 유동장의 정상/비정상 유동해석을 위해 압축성 Navier-Stokes 방정식이 사용되었으며, 해석결과는 모선과 로켓간의 충격파-팽창파 간섭효과를 잘 보여주고 있다. 무게중심의 변화에 따른 로켓의 거동을 예측하기 위하여 세 가지 경우에 대한 전산해석을 수행하였으며, 결과적으로 초음속 공중발사 로켓의 안전한 모선분리를 위한 설계 가이드라인을 제시하였다.

• 전자통신동향분석
• /
• 제38권3호
• /
• pp.1-10
• /
• 2023

In this study, the status of global advanced air mobility (AAM) was investigated to derive information and communications technologies (ICTs) that should be prepared according to directions of domestic AAM development. AAM is an urban air traffic system for moving from city to city by electric vertical take-off and landing or personal aircraft. It is expected to establish a three-dimensional air traffic system that can solve ground traffic congestion caused by the rapid global urbanization. With the full-scale commercialization of AAM solutions, high-density air traffic is expected, and with the advent of the personal air vehicle (PAV), the flight space usage is expected to expand. Therefore, it is necessary to develop a safe AAM service through early research on core ICTs for autonomous flight.

• 센서학회지
• /
• 제15권6호
• /
• pp.442-448
• /
• 2006

Ultrasonic anemometers using pulse envelope detection-based method are standard instruments in most meteorological studies. In this paper, a new phase measurement method is tried to achieve the enhanced resolution without changing dimensions. The measurement sensitivity, dynamic range, and measurement speed of the new instrument are 0.2 mm/s, 13.3 m/s, and 13 measurements/sec, respectively. A graphic user interface is added to show the velocity and direction of the wind with the speed of sound and temperature of the wind in the 3 dimensional space. The new anemometer could be useful for the measurement of the air speed, the flow of fluids, and even air flow inside the downtown buildings.

• 한국항공우주학회지
• /
• 제33권8호
• /
• pp.18-25
• /
• 2005

본 논문에서는 공중발사로켓의 초음속 모선 분리 현상에 관하여 기술하였다. 정상상태와 비정상상태의 해석을 위하여 3차원 Euler방정식을 수치적으로 계산하였다. 해석결과는 모선과 로켓사이의 충격파 간섭현상을 명확히 보여주고 있으며, 로켓의 분리 단계에 중요한 영향을 미치는 인자들을 해석을 통해 찾아내었다. 결과적으로 본 연구를 통하여 초음속 공중발사로켓의 설계에서의 안전한 모선분리를 위한 가이드라인을 제공하였다.

• 한국항공우주학회지
• /
• 제33권4호
• /
• pp.17-26
• /
• 2005

새로운 개념의 위성발사 방식으로 연구되고 있는 초음속 공중발사로켓의 모선분리 현상을 파악하기 위하여 모선-로켓의 단순화된 형상에 대하여 발사속도, 장착각, 수평-수직방향의 장착위치 변화에 따른 발사체의 피칭모멘트의 변화를 고찰하였다. 정상상태의 유동해석을 위하여 삼차원 Euler 방정식을 수치적으로 해석했고, 이러한 연구를 통하여 모선날개에 장착된 초음속 공중발사로켓의 모선분리에 큰 영향을 주는 장착변수를 확인하였으며 각 변수의 변화에 따른 발사체의 거동의 변화를 반응면 모델을 구성하여 도식으로 나타내었다. 본 연구를 통하여 초음속 공중발사 메커니즘에 대한 공력특성과, 비정상 모선분리를 위한 최적 장착 위치에 대한 유용한 데이터를 제공하게 되었다.

• 동력기계공학회지
• /
• 제16권5호
• /
• pp.47-54
• /
• 2012

The steady three-dimensional numerical analysis on the thermal flow using standard k-${\varepsilon}$ turbulence model was carried out to investigate the air cooling effect of a cooler on the cabin for a commercial vehicle. Here, the heat exchanging method of this cabin cooler uses the cooling effect of a thermoelectric module. In consequence, the air system resistance of a cooler within the cabin is about 12.1 Pa as a static pressure, and then the operating point of a virtual cross-flow fan considering in this study is formed in the comparatively low flowrate region. The discharging air temperature of a cooler is about $14{\sim}15^{\circ}C$. Moreover, the air cooling temperature difference obtained under the outdoor cabin temperature of $40^{\circ}C$ shows about $7{\sim}9^{\circ}C$ in a driver resting space and about $9{\sim}14^{\circ}C$ in the front of a driver's seat including the space of a driver's foot.