• 한국방재학회지
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• 제2권4호
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• pp.40-47
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• 2002

Since it is important to understand the bio-climatic change in Seoul for ecological city planning in the future, this paper gives an overview on bio-climate analysis of urban environments at Seoul. We analyzed its characteristics in recent years using the observations of 24 of Automatic Weather Station (AWS) by Korea Meteorological Administration (KMA). In urbanization, Seoul metropolitan area is densely populated and is concentrated with high buildings. This urban activity changes land covering, which modifies the local circulation of radiation, heat and moisture, precipitation and creating a specific climate. Urban climate is evidently manifested in the phenomena of the increase of the air temperature, called urban heat Island and in addition urban sqall line of heavy rain. Since a city has its different land cover and street structure, these form their own climate character such as climate comfort zone. The thermal fold in urban area such as the heat island is produced by the change of land use and the air pollution that provide the bio-climate change of urban eco-system. The urban wind flow is the most important climate element on dispersion of air pollution, thermal effects and heavy shower. Numerical modeling indicates that the bio-climatic transition of wind wake in urban area and the dispersion of the air pollution by the simulations of the wind variation depend on the urban land cover change. The winds are separately simulated on small and micro-scale at Seoul with two kinds of kinetic model, Witrak and MUKLIMO.

• 한국컴퓨터정보학회논문지
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• 제15권8호
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• pp.79-87
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• 2010

모바일 멀티미디어 환경에서 초고속의 서비스를 요구하는 다수의 사용자를 수용하려면 마이크로/피코 셀과 같이 셀의 크기를 더욱 줄여서 무선 자원의 재사용성을 증대시켜야 한다. 특히 멀티미디어 트래픽의 전송 중에 핸드오버가 발생한다면, 멀티미디어 트래픽의 QoS가 지연 및 손실에 의하여 영향 받기 때문에 정지 상태와 동일한 QoS를 유지하기 위하여 효율적인 자원 예약 및 할당 방안이 필요하다. 본 논문에서는 차세대 이동 통신망에서 멀티미디어 서비스의 효율적인 QoS를 제공하기 위한 방안의 하나로서, 수락 제어, 부하 제어 그리고 패킷 스케쥴러와 밀접한 관련성을 갖는 자원 할당 방법을 제안한다. 시뮬레이션을 통하여 제안된 방법의 우수성을 평가한다.

• 설비공학논문집
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• 제27권8호
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• pp.426-431
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• 2015

The advantages of a printed circuit heat exchanger (PCHE) are the compactness and efficiency derived from its heat-transfer characteristics; furthermore, a PCHE for which a diffusion bonding method was used during production can be applied to extreme environments such as a cryogenic condition. In this study, a micro-channel PCHE fabricated by diffusion bonding was investigated in a cryogenic environment regarding its thermal performance and the pressure drop. The test rig consists of an LN2 storage tank, vaporizers, heaters, and a cold box, whereby the vaporized cryogenic nitrogen flows in hot and cold streams. The overall heat-transfer coefficients were evaluated and compared with traditional correlations. Lastly, we suggested the modified heat-transfer correlations for a PCHE in a cryogenic condition.

• 한국측량학회지
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• 제38권5호
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• pp.467-476
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• 2020

Indoor space has been one of the focal points for geospatial research as various factors such as increasing demands for application and demand for adaptive response in emergencies have arisen. IndoorGML (Indoor Geography Markup Language) has provided a standardized method of representing the topological aspect of micro-scale environments, with its extensive specifications and flexible applicability. However, as more real-world problems and needs demand attention, suggestions to improve this standard, such as representing IndoorPOI (Indoor Points of Interest), have arisen. Hence, existing algorithms and functionalities that we use on perceiving these indoor spaces must also adapt to accommodate said improvements. In this study, we explore how to define spatial neighborhoods in indoor spaces represented by an integrated IndoorGML and IndoorPOI data. We revisit existing approaches to combine the aforementioned datasets and refine previous approaches to perform neighborhood spatial queries in 3D. We implement the proposed algorithm in three use cases using sample datasets representing a real-world structure to demonstrate its effectiveness for performing indoor spatial analysis.

• 한국산학기술학회논문지
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• 제8권1호
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• pp.73-81
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• 2007

본 논문에서는 마이크로 셀과 매크로 셀이 중첩된 구조를 갖는 이동통신 환경에서 핸드오버의 성능을 분석하였다. 제안한 모델에서는 고속으로 이동하는 가입자를 마이크로 셀로 핸드오버하지 않고 매크로 셀로 핸드오버하는 경우의 성능을 분석하였다. 분석의 용이함을 위해 마이크로 셀과 매크로 셀의 모양은 원형이라고 가정하였다. 마이크로 셀에는 저속의 핸드오버 호를 위하여 큐를 두는 방식과 매크로 셀에는 고속의 핸드오버 호를 위하여 예약채널 할당방식을 적용하였다 해석적인 분석결과, 제안한 방식에서 새로운 호의 블러킹 확률의 증가는 미비하면서 랜드오버 실패 확률은 중첩되지 않은 셀 구조를 갖는 시스템에 비해 상대적으로 낮음을 알 수 있었다.

• 보존과학연구
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• 통권16호
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• pp.59-111
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• 1995

Chemical composion and crystal form of Corrosion products found on archaeological iron objects were analyzed using X-ray fluorescence analysis, micro-X-ray powder diffraction analysis and ion chromatographic technique. The nature and behavior of the corrosion products were studied in order to aid in the conservation and restoration of burial iron objects. Twenty-two samples analyzed in this study were collected from iron object found in Korea and Japan. The corrosion products of iron objects from burial mounds contain $\alpha$-FeOOH, $\beta$-FeOOH, $\gamma$-FeOOH, $Fe_3O_4$and amorphous iron hydroxides. The content of $\alpha$-HeOOH is the greatest. Because, Ageing for long period should change the amorphous iron hydroxides is considerably less than that in usual atmospheric corrosion products. The concentration of chlorine and sulfine is remarkably variable ($Cl^-$ : 100- 30,000ppm, $SO_4^-2$ : 20-10,000ppm),but the reasons are unclear. The presence of generally high concentrations of chlorine and sulfine the corrosion products of iron objects seem to be influenced by the marine climatic condition. The presence of high chlorine and sulfine concentrations in the corrosion products of iron objects seem to be influenced by the marine burial environments.

• 한국전자통신학회논문지
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• 제16권2호
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• pp.363-370
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• 2021

외곽 침입감지 시스템은 물리 보안에 있어서 중요한 비중을 차지하고 있다. 본 연구에서는 외곽 침입감지를 위해 IoT 환경에서 적용할 수 있는 MEMS 센서를 활용한 초소형 스마트 디바이스를 개발하고 그 성능을 평가하였다. 본 연구에서 개발한 스마트 디바이스를 적용한 외곽 침입감지 시스템은 다양한 재질, 형태의 철조망이 도심, 바닷가, 산속 등 다양한 설치환경에 설치되어 외부의 침입과 그 위치를 감지할 수 있을 뿐 아니라, 오경보율과 구축비용 등을 최소화할 수 있는 스마트 센서로 국가 및 민간 주요 시설의 외각 침입 감지 위해 활용될 수 있을 것으로 기대한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.3862-3879
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• 2019

More and more problems for public security have occurred due to the limited solutions for drone detection especially for micro-drone in long range conditions. This paper aims at dealing with drones detection using a radar system. The radio frequency (RF) signals emitted by a controller can be acquired using the radar, which are usually too weak to extract. To detect the drone successfully, the static clutters and linear trend terms are suppressed based on the background estimation algorithm and linear trend suppression. The principal component analysis technique is used to classify the noises and effective RF signals. The automatic gain control technique is used to enhance the signal to noise ratios (SNR) of RF signals. Meanwhile, the empirical mode decomposition (EMD) based wavelet transform (WT) is developed to decrease the influences of the Gaussian white noises. Then, both the azimuth information between the drone and radar and the bandwidth of the RF signals are acquired based on the statistical analysis algorithm developed in this paper. Meanwhile, the proposed accumulation algorithm can also provide the bandwidth estimation, which can be used to make a decision accurately whether there are drones or not in the detection environments based on the probability theory. The detection performance is validated with several experiments conducted outdoors with strong interferences.

• 한국건축시공학회지
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• 제20권6호
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• pp.577-584
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• 2020

Construction automation and robotics have been widely adopted in the construction industry as a promising solution to such issues like a shortage of skilled labor and the difficulties workers face in harsh working environments. The analysis of the knowledge structure and its evolution from the existing articles helps identify essential knowledge elements and possible future research directions. This study attempts to (1) construct keyword networks from the papers published in the International Symposium on Automation and Robotics in Construction (ISARC), (2) investigate how keywords and keyword communities are associated with each other, and (3) examine the changes in the crucial keywords over time. Through cluster analysis, 79 keywords were categorized into four groups (BIM, Building construction, Sensing, and GPS as representative keywords) with similar structural positions. Research trends show that research themes related to Infrastructure, Construction equipment, and 3D have consistently received a large amount of attention, regardless of geographical region. Research on as-built status model utilization through BIM and Laser scanning and improving Energy performance is taking place more frequently. In contrast, research studies related to problem-solving based on Neural networks are not as common as previously. This study provides useful insights into the construction automation field, at both the macro and micro levels.

• 한국분말재료학회지
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• 제27권6호
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• pp.477-483
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• 2020

Metal-organic frameworks (MOFs) are of significant interest because of their high porosity, which facilitates their utilization in gas storage and catalysis. To enhance their current properties in these applications, it is necessary to elucidate the interactions between molecules in a confined environment that differ from those in bulk conditions. Herein, we study the confined molecular interaction by investigating the solvent-dependent photophysical properties of two different-sized molecules inside MOF-5. Ruthenium tris-bipyridine (Rubpy) and coumarin 153 (C153) are encapsulated in MOF-5. Rubpy with MOF-5 (Rubpy@MOF) is prepared by building MOF-5 around it, resulting in limited space for solvent molecules in the pores. The smaller C153 is encapsulated in the preformed MOF-5 (C153@MOF) by simply soaking the MOF in a concentrated C153 solution. C153@MOF permits more space for solvent molecules in the pore. Their characteristic absorption and emission spectra are examined to elucidate the confined molecular interactions. Rubpy@MOF and C153@MOF exhibit different spectral shifts compared to the guest molecules under bulk conditions. This discrepancy is attributed to the different micro-environments inside the pores, derived from confined host-guest interactions in the interplay of solvent molecules.