• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.345-346
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• 2008

본 논문은 원자력 발전소내의 기기들 중 원자로 내부 기기의 초음파 비파괴 검사를 위한 로봇의 위치 제어를 위한 방법을 설명하였다. 기존에는 레일과 같은 보조 시설물을 설치하여 검사를 하는 것이 일반적이었다. 본 논문에서는 이러한 보조 시설물 없이 카메라 영상에 의한 위치제어에 관하여 기술하였다. 여러 가지 방법 중에 정합 필터를 이용하여 로봇의 현재위치를 추정하는 방법을 사용하였다. 본 논문에서 제안된 방법을 실험한 결과 로롯의 제어를 위한 샘플링 타임은 100msec 정도로 일반석인 로봇의 제어 주기로 사용하기에는 다소 길었다. 이를 해결하기 위하여 정합필터를 병렬 계산을 이용하여 계산하도록 하고 이를 병렬언어로 널리 사용되고 있는 MPI(Message Passing Interface) 언어로 구현하였다. 다수의 컴퓨터와 이더넷을 이용할 수 있으며 최근 일반화되고 있는 멀티코어 CPU도 응용이 가능하였다.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.165-176
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• 2005

Natural gas in deep sediment may occur in three phases based on the physical and chemical conditions. If the concentration of gas in pore water is less than the solubility, gas is dissolved. If the concentration of gas is greater than its solubility (water is saturated or supersaturated with gas), gas occurs as a fee gas below the gas hydrate stability Lone (GHSZ) and is present as solid hydrate within the GHSZ. The knowledge of gas concentration in deep sediment appears critical to determine the phase of natural gases and to understand the formation and distribution of gas hydrate. However, reliable data on gas concentration are usually available only from the upper section of marine sediment by the headspace gas technique, which is widely used for sampling of gases from the sediments. The headspace gas technique represents only a fraction of gases present in situ because sediments release most of the gases during recovery and sampling. The PCS (Pressure Core Sampler) is a downhole tool developed to recover a nominal $1{\cal}m$ long, $4.32{\cal}cm$ diameter core containing $1,465cm^3$ of sediment, pore water and gas at in situ pressure up to 68.9 MPa. During Leg 204, the PCS was deployed at 6 Sites. In situ methane gas concentration and distribution of gas hydrate was measured by using PCS tool. Characteristics of methane concentration and distribution is different from site to site. Distribution of gas hydrate in the study area is closely related to characteristics of in situ gas concentration measured by PCS.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.340-342
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• 2004

Promsearch는 인간 DNA에서 코어 프로모터 영역을 예측하는 프로그램이며, PWM(position weight matrix)과 신경망을 기반으로 전사시작지점을 예측한다. 프로그램은 대량의 서열 데이터를 처리할 수 있도록 구성되었으며, 본 논문에서는 인간 염색체 22번에 대한 프로모터 예측 결과를 제시한다. Annotated된 936개의 유전자와 Promsearch가 예측한 프로모터간의 위치의 상관관계를 계산한 결과 87개에 대해 프로모터 예측 결과가 의미 있는 것으로 밝혀졌다. 예측의 민감도는 25%이며, Promsearch가 대규모 시퀀싱 프로젝트에서 나오는 대량의 서열 데이터를 1차적으로 분석하는 도구로서 사용될 수 있음을 확인하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.37-37
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• 2000

일반적으로 노즐 입구의 압력과 배압의 비가 어떤 임계값보다 큰 경우에 축소확대 노즐을 통하는 유동은 노즐목에서 초크하며, 노즐출구에서는 용이하게 초음속으로 된다. 노즐을 통하여 초음속으로 방출되는 제트유동에 관해서는 현재까지 많은 연구가 수행되었다. 이들 연구에 의하면 노즐 압력 비에 따라 노즐출구에서의 유동상태(즉 과팽창, 적정팽창, 부족팽창상태)가 결정되며, 노즐출구로부터 하류의 초음속 제트유동에서 발생하는 충격파 구조 및 위치, 제트경계의 구조 그리고 제트의 코어 등 유동의 기구가 비교적 상세하게 알려져 있다.(중략)

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1493-1504
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• 2021

Purpose This study aimed to evaluate the utility of the 16-cm axial volume scan technique for calculating the coronary artery calcium score (CACS) using non-enhanced chest CT. Materials and Methods This study prospectively enrolled 20 participants who underwent both, non-enhanced chest CT (16-cm-coverage axial volume scan technique) and calcium-score CT, with the same parameters, differing only in slice thickness (in non-enhanced chest CT = 0.625, 1.25, 2.5 mm; in calcium score CT = 2.5 mm). The CACS was calculated using the conventional Agatston method. The difference between the CACS obtained from the two CT scans was compared, and the degree of agreement for the clinical significance of the CACS was confirmed through sectional analysis. Each calcified lesion was classified by location and size, and a one-to-one comparison of non-contrast-enhanced chest CT and calcium score CT was performed. Results The correlation coefficients of the CACS obtained from the two CT scans for slice thickness of 2.5, 1.25, and 0.625 mm were 0.9850, 0.9688, and 0.9834, respectively. The mean differences between the CACS were -21.4% at 0.625 mm, -39.4% at 1.25 mm, and -76.2% at 2.5 mm slice thicknesses. Sectional analysis revealed that 16 (80%), 16 (80%), and 13 (65%) patients showed agreement for the degree of coronary artery disease at each slice interval, respectively. Inter-reader agreement was high for each slice interval. The 0.625 mm CT showed the highest sensitivity for detecting calcified lesions. Conclusion The values in the non-contrast-enhanced chest CT, using the 16-cm axial volume scan technique, were similar to those obtained using the CACS in the calcium score CT, at 0.625 mm slice thickness without electrocardiogram gating. This can ultimately help predict cardiovascular risk without additional radiation exposure.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.9
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• pp.407-415
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• 2007

In parallel cluster computing systems, the efficiency of communication between computing nodes is one of important factors that decide overall system performance. Accordingly, many researchers have studied on high-performance inter-node communication. The recently launched multi-core processor, however. increases the importance of intra-node communication as well because the more the number of cores in a node, the more the number of parallel processes running in the same node. Though there have been studies on intra-node communications, these have limited considerations on the state-of-the-art systems. In this paper, we propose a Linux kernel module that minimizes the number of data copy by exploiting the memory mapping mechanism for high-performance intra-node communication. The proposed kernel module supports the Linux kernel version 2.6. The performance measurements over a multi-core system present that the proposed kernel module can achieve lower latency up to 62% and higher throughput up to 144% than an existing kernel module approach. In addition, the measurements reveal that the performance of intra-node communication can vary significantly based on whether the cores that run the communication processes are belong to the same processor package (i.e., sharing the L2 cache).

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.25-32
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• 2007

This study is to evaluate the effect of chemical attack on durability and deterioration of lining concrete in tunnel. Surface examination, nondestructive inspection, uniaxial compressive strength test, carbonation test, chloride diffusion test, micro-structural analysis were performed to analyze the deterioration of lining concrete in tunnel constructed 70 years ago. From surface examination results, the tunnel had been repaired and reinforced in several times. It has many cracks, water-leakage, efflorescence and exploitation. Compressive strengths obtained from nondestructive inspection and uniaxial compressive strength test have measured $17.5{\sim}34.7MPa$, and $12.8{\sim}40.3MPa$, respectively. Carbonation depth specimen cored from concrete lining has ranged from 3mm to 27mm. From chloride diffusion test, most specimens have low permeability. And the XRD analysis was able to detect ettringite and thaumasite, which were confirmed by SEM and EDS results to be the causes for the deterioration of lining concrete.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1019-1022
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• 2003

최근 이동통신 시장의 급속한 발전은 모바일 단말기를 통한 다양한 부가서비스에 대한 필요성을 증대시켰다. 특히, 친구찾기와 같은 개인의 위치추적을 위한 서비스가 새로운 Killer-application으로 인식되면서 빠른 시장성을 예측하고 있다. 이러한 서비스에 대한 기술은 일반 대중뿐만 아니라 긴급구조시스템, 재난관리시스템 등 공공 및 개인의 안전과 효율적인 자원의 관리를 위한 국가 정보 인프라로서 정보통신 기술 활용 등 사회적인 요구 증가에 부합된다. 본 연구는 무선 이동통신망을 이용하여 긴급한 환경에 처해있는 개인 가입자의 위치를 파악하고 신속히 대처 할 수 있는 무선긴급서비스를 위해 요구되는 기능 및 조건의 기술규격 설계 등에 관한 것이다. 본 논문에서는 국내외 표준을 충분히 수용한 모바일 환경에서 무선긴급서비스의 1)기술규격 범위 및 네트워크 참조 모델을 정의하고 2) 제시된 네트워크 모델의 코어 망과 긴급구조 서비스 망에 대한 기능 정의 및 요구조건에 대해 설계하고자 한다.

• Korean Journal of Optics and Photonics
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• v.33 no.6
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• pp.252-259
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• 2022

We have conducted a study to control the light-intensity distribution at the output end of a multimode optical fiber via estimating the transmission matrix. A circularly arranged Hadamard eigenmode phase distribution was implemented using a spatial light modulator, and the transmission matrix of a multimode optical fiber was experimentally obtained using a four-phase method. Based on the derived transmission matrix, the spatial phase distribution of light incident upon the optical fiber was adjusted via the spatial light modulator in advance, to focus the light at a desired position at the optical fiber output. The light could be focused with an intensity up to 359.6 times as high as that of the surrounding background signal at a specific position of the multimode fiber's output end, and the intensity of the focused beam was on average 104.6 times as large as that of the background signal, across the area of the multimode fiber's core.

• Journal of IKEEE
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• v.25 no.1
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• pp.95-100
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• 2021

If we know the location of the hull block and the welding feeder in the shipyard, we can easily obtain the location information of the worker. That data is very useful for implementing a workplace safety monitoring system. However, it is difficult to apply a fixed communication network to the workplace due to the specificity of the hull structure and welding process. In this study, inductive power line communication, which can replace dedicated communication line, was reviewed. A ferrite core was used as an inductive coupler to be installed on the power cable of the welding machine, and a nano-crystalline core was applied as a coupler to be fastened to the support rod of the metal block. In order to visualize the operating principle of the proposed couplers, 3D modeling and finite element analysis were performed with the COMSOL AC/DC module. In the communication performance test using an aluminum profile, when the communication channel was formed by the contact of the welding electrode, the bandwidth was kept above 6 Mbps.