• The Science & Technology
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• no.1 s.428
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• pp.87-92
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• 2005

1905년은 아인슈타인의 일생 가운데 가장 생산적인 해였다. 그는 그 해에 특수 상대론, 광전효과, 브라운 운동 및 E=mc² 등 네편의 주옥같은 논문을 발표했다. 한국물리학회와 과학문화진흥회는 이를 기념하기 위하여 2005년 7월 1일부터 2006년 2월말 까지 창경원 옆에 있는 서울 과학관에서 아인슈타인 100주년 기념 전시회를 갖는다. 전시회는 1)아인슈타인의 생애 2)시간과 공간 3)빛, 파동 및 물질 4)아인슈타인의 우주 5)아인슈타인과 예술 등 다섯 가지 주제를 체험위주로 기획하고 있다. 관람객들이 특수 상대론을 설명이 아니라 체험함으로써 일상생활에서는 어떻게 이용되고 있는가를 알도록 전시장을 꾸미고 있다. 각 주제별로 그 내용을 스케치해본다.

• Korean Journal of Logic
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• v.9 no.1
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• pp.31-62
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• 2006

이 논문은 포퍼의 후기 확률론인 성향적 확률론에 대한 것이다. 포퍼가 확률에 관한 성향이론을 제시한 가장 중요한 동기는 단일 사건에 확률값을 부여하기 위함이었다. 그의 성향이론은 전기와 후기로 나누어지는데, 전기의 이론은 성향을 반복가능한 조건들의 집합으로, 후기의 이론은 성향을 특정 시각에서의 우주의 상태로 설명한다. 이 글은 포퍼의 전기와 후기 성향이론이 성공적이지 않음을 논증한다. 전기 성향이론에 대해서는 가장 좁은 준거집합의 원리의 문제에 부딪혀서 단일 사건에 대하여 객관적인 확률값을 부여할 수 없기 때문이고, 후기 성향이론은 성향을 약한 인과라고 해석하는 문제와 함께 포퍼 자신의 의도와 달리 형이상학적인 이론이 되어버렸기 때문이다.

• Atmosphere
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• v.28 no.4
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• pp.443-455
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• 2018

Nowcasting algorithms using weather radar data are mostly based on extrapolating the radar echoes. We estimate the echo motion vectors that are used to extrapolate the echo properly. Therefore, understanding the general characteristics of these motion vectors is important to improve the performance of nowcasting. General characteristics of radar-based motions are analyzed for warm season precipitation over Jeju region. Three-year summer season data (June~August, 2011~2013) from two radars (GSN, SSP) in Jeju are used to obtain echo motion vectors that are retrieved by Variational Echo Tracking (VET) method which is widely used in nowcasting. The highest frequency occurs in precipitation motion toward east-northeast with the speed of $15{\sim}16m\;s^{-1}$ during the warm season. Precipitation system moves faster and eastward in June-July while it moves slower and northeastward in August. The maximum frequency of speed appears in $10{\sim}20m\;s^{-1}$ and $5{\sim}10m\;s^{-1}$ in June~July and August respectively while average speed is about $14{\sim}15m\;s^{-1}$ in June~July and $8m\;s^{-1}$ in August. In addition, the direction of precipitation motion is highly variable in time in August. The speed of motion in Lee side of the island is smaller than that of the windward side.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.12-20
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• 2024

The application of reinforcement design to ensure the structural safety of electronics in small satellites is limited by the spatial constraints of the satellite structure during launch vibrations. Additionally, a reliable evaluation approach is needed for mounting highly integrated devices that are susceptible to fatigue failure. Although the Steinberg fatigue failure theory has been used to assess the structural integrity of electronic devices, recent studies have highlighted its theoretical limitations. In this paper, we propose a structural methodology based on the critical strain theory to design the digital control unit (DCU) of the X-band SAR payload component for the small SAR technology experimental project (S-STEP), a small satellite constellation. To validate the design, we conducted modal and random analyses using simplified modeling techniques. Based on our methodology, we ultimately demonstrated the structural safety of the electronics through analysis results, safety margin derivation, and functional tests conducted both before and after the launch test.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.47-55
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• 2021

When an abnormal landing occurs, aircraft structures should be designed to guarantee occupants survivability without preventing egress. To find out fire root causes at crash, lots of fixed aircraft crash tests were conducted. Appropriate crash load factors were established with the comprehension of structural behavior based on dynamic analysis and investigation of human tolerance. Cargo restraint criteria were set up considering passengers safety and operational cost while analyzing past cargo aircraft accident data using a probabilistic approach. Reviewing results of past crash tests, current crash landing load factor was appreciated physically, medically, and economically.

• Journal of Science and Technology Studies
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• v.9 no.2
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• pp.29-49
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• 2009

This study not only suggests a methodology of science planning different from technology planning, but also applies the methodology to the case of astronomy and space science project. Throughout the analysis on this practice, we have provided logical tools for science project planning, and have identified a decision making process in science which has been regarded to be in a 'black box'. Therefore, this science planning technique can contribute to a more rationalized allocation of scientific resource at a project level as well as at a national level. In particular, catch-up countries in a transition to post catch-up stage such as Korea can establish a more efficient national R&D system by application of science planning concept to an emerging technology area.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.783-789
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• 2020

This paper proposes a new method for vision-based navigation using semantically segmented aerial images. Vision-based navigation can reinforce the vulnerability of the GPS/INS integrated navigation system. However, due to the visual and temporal difference between the aerial image and the database image, the existing image matching algorithms have difficulties being applied to aerial navigation problems. For this reason, this paper proposes a suitable matching method for the flight composed of navigational feature extraction through semantic segmentation followed by template matching. The proposed method shows excellent performance in simulation and even flight situations.

• Korean Journal of Construction Engineering and Management
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• v.24 no.3
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• pp.31-41
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• 2023

This study is a study to develop a configuration management methodology for efficient and systematic management in the event of configuration changes such as deformation, explosion, and remodeling of launch vehicle development test facilities, which are emerging as important national facilities in the era of full-scale space competition. Through the analysis of international standards for configuration management, a configuration management process framework to be applied to launch vehicle development test facilities is extracted, a survey was conducted on experts who performed life cycle engineering of launch vehicle development test facilities, and a configuration management methodology optimized for operation/management of domestic launch vehicle development test facilities was proposed. Identify the configuration for launch vehicle development test facilities, the configuration management manager, configuration management organization, and configuration management board approve/process the configuration changes, and after construction is completed according to design requirements, launch vehicle development test facilities try to manage the configuration in a controlled state.

• Publications of The Korean Astronomical Society
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• v.6 no.1
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• pp.27-37
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• 1991

두 스칼라장 $\phi_1$, $\phi_2$를 사용한 원시 검은 구멍 생성모형을 살펴보았다. $\phi_1$은 Linde의 혼돈 인플레이션장을, 그리고 $\phi_2$는 SU(5) 대통일 이론의 Higgs장을 사용하였다. 인플레이션은 $\phi_1$에 의해서 일어난다고 가정하였는데, 재가열(reheating) 온도가 $\phi_2$장의 임계온도(${\sim}1.31{\times}10^{14}GeV$)보다 높을 경우 재가열 직후에 검은 구멍이 생성됨을 알 수 있었다. 재가열 온도가 $1.48{\times}10^{14}GeV$정도 되면, 질량이 1kg쯤인 검은 구멍이 생성되는데, 현재의 지평선에 해당되는 당시의 영역 내에서 생성되었던 검은 구멍들의 총 질량이 ${\sim}10^{55}g$($\approx$현재 우주의 지평선 질량)이 되어, 그 증발과정이 우주론적으로 중요해질 수 있다.

• Bulletin of the Korean Space Science Society
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• 1993.04a
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• pp.7.1-7
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• 1993

위성의 정밀 거리 결정을 위해 1993년 9월 5일부터 IS일간 중국의 상해 천문대 Sheshan관측소와 장춘 인공위성 관측소에서 LAGEOS 11 (Laser Geodynamics Satellite II)에 대한 SLR (Satellite Laser Ranging) 관측을 수행하였다. SLR 관측에서는 지상의 관측소에서 발사한 LASER 펄스 (pulse)가 반사경들(retroflectors)로 둘러싸인 인공위성에 반사되어 돌아오는 RTT (Round Trip Time)를 측정하여 위성까지의 거리를 결정하는데, 관측된 시간과 거리 자료는 많은 잡음(noise)를 포함하고 있기 때문에 정확한 자료를 얻기 위해서는 많은 보정이 필요하다. 관측된 시간, 거리 자료를 지상 목표물 조준(ground target ranging )에 의한 system보정, 원자시계와 GPS에서 수신된 시간과의 시간 비교, 측정된 온도, 기압, 상대 습도에 따른 대기 영향의 보정 등을 통해 오차를 줄이고 다시 LASERF beam의 대기 굴절에 따른 거리 변화 보정, 위성의 질량 중심 거리(offset) 보정, 조석력에 의한 변화값 보정, 전자기적 지연(electromagnetic delay)에 의한 상대론적 보정등을 통해서 정밀한 거리 자료를 얻었다.