• 융합보안논문지
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• 제10권1호
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• pp.9-17
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• 2010

인트라넷의 네트워크는 악성트래픽의 확산과 분산을 차단하는 역할이 수행되는 영역이다. 네트워크 구조상에서는 트래픽 소통경로상에서 악성코드 침투와 보안차단기능이 수행된다. 네트워크보안 아키텍쳐란 침투와 보안차단기능이 수행되는 네트워크 구조상에서의 트래픽처리 영역과 그룹을 차별화하여 구분시키는 개념이다. 인트라넷 네트워크 아키텍쳐는 보안도메인은 영역과 가능을 기준으로 차별화가 가능하고 따라서 도메인별로 차별화된 보안 메커니즘이 개발되고 적용되어야한다. 본 논문는 네트워크 아키텍쳐의 보안 취약성을 진단하고 네트워크는 구조적으로 어떤 가준으로 보안 도메인이 설정되어야하는가에 대한 방법론 개발을 위해 네트워크 형상(Topology) 결정 요소, 보안 아키텍쳐 설정기준, 구조도 선택기준, 차단위치 결정, 경로 방역망 구성기준을 도출한다. 설계된 방법론을 적용할 경우 전통적인 네트워크 구조상에서보다 바이러스 차단 효율이 증대되고 있음이 실험을 통해 입증한다. 따라서 아키텍쳐 영역기준에 따라 차별화된 차단기능이 필요하며 보안 메커니즘 개발이 요구되고 있음을 본 연구를 통해 제시하고자한다.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.193-212
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• 2009

The resilience of a city confronted with a terrorist bomb attack is the background of the paper. The resilience strongly depends on vital infrastructure and the physical protection of people. The protection buildings provide in case of an external explosion is one of the important elements in safety assessment. Besides the aspect of protection, buildings facilitate and enable many functions, e.g., offices, data storage, -handling and -transfer, energy supply, banks, shopping malls etc. When a building is damaged, the loss of functions is directly related to the location, amount of damage and the damage level. At TNO Defence, Security and Safety methods are developed to quantify the resilience of city infrastructure systems (Weerheijm et al. 2007b). In this framework, the dynamic response, damage levels and residual bearing capacity of multi-storey RC buildings is studied. The current paper addresses the aspects of dynamic response and progressive collapse, as well as the proposed method to relate the structural damage to a volume-damage parameter, which can be linked to the loss of functionality. After a general introduction to the research programme and progressive collapse, the study of the dynamic response and damage due to blast loading for a single RC element is described. Shock tube experiments on plates are used as a reference to study the possibilities of engineering methods and an explicit finite element code to quantify the response and residual bearing capacity. Next the dynamic response and progressive collapse of a multi storey RC building is studied numerically, using a number of models. Conclusions are drawn on the ability to predict initial blast damage and progressive collapse. Finally the link between the structural damage of a building and its loss of functionality is described, which is essential input for the envisaged method to quantify the resilience of city infrastructure.

• 대한전자공학회논문지TC
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• 제44권6호
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• pp.1-8
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• 2007

한정된 배터리 전원을 사용하는 무선 센서 네트워크에서 노드의 수명유지를 위해 전력 소모량은 매우 중요한 문제이다. 전력소모를 줄이기 위해 저전력 RF 통신을 사용함으로써 무선 센서 네트워크의 에러 발생률이 증가하게 된다. 본 논문에서는 무선 센서 네트워크의 오류 정정 부호 사용과 그에 따른 전력 소모량을 분석하였다. 오류 정정 부호는 변 복조 과정에서 소모되는 저려 소모가 있지만, 부호화 이득을 통해 전송 에너지를 절약할 수 있다. 센서 노드의 특성상 전송 에너지는 프로세서의 계사에 소모되는 에너지보다 큰 비중을 차지하고 있다. 본 논문에서는 낮은 전송 전력으로 전송한 데이터를 짧은 구속장의 Viterbi 알고리즘을 적용하여 오류 정정을 할 경우 단순한 ARQ(Auto Repeat Request) 방식을 사용할 경우보다 최대 20%의 재전송 횟수의 감소와 18%의 전력 소모의 감소를 분석하였다.

• 대한전자공학회논문지TC
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• 제45권8호
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• pp.75-81
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• 2008

본 논문에서는 MPIC를 적용한 다중코드 CDMA 시스템에서 보다 정확인 BER 성능 분석 기법을 다중경로 페이딩 채널이 대하여 제안한다. 이를 위해 MPIC를 적용한 기존의 성능 분석 기법들의 문제점을 설명한다. 즉 기존의 성능분석 결과가 MPIC를 적용하지 않은 경우에 대해서도 모의실험 결과와 일치하지 않음을 보인다. 이러한 불일치는 MPIC를 적용한 경우에 대해서도 성능 불일치를 야기하기 때문에 MPIC를 적용하지 않은 경우에 대한 성능 불일치를 야기하는 이론적 원인을 밝히는 것이 반드시 선행되어야만 한다. 본 논문에서는 기존의 성능 분석 결과와 모의실험 결과의 차이가 CDMA 시스템 성능분석에서 사용된 일반적인 가우시안 근사화가 아니라 이에 더하여 가정되는 부가적인 가우시안 근사화에 의해 야기됨을 확인하였다. 이를 바탕으로 본 논문에서는 부가적 가우시안 근사화를 사용하지 않는 보다 정확한 성능 분석 기법을 제안하고 이를 모의실험을 통해 검증하였다. 뿐만 아니라 제안된 기법이 MPIC의 적용을 통하여 얻을 수 있는 시스템의 이론적 성능한계를 나타냄을 확인하였다.

• Nuclear Engineering and Technology
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• 제36권6호
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• pp.528-539
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• 2004

It is essential in commercial reactors that the safety limits imposed on the fuel pellets and fuel clad barriers, such as the linear power density (LPD) and the departure from nucleate boiling ratio (DNBR), are not violated during reactor operations. In order to accurately monitor the safety limits of current reactor states, a detailed three-dimensional (3D) core power distribution should be estimated from the in-core detector signals. In this paper, we propose a calculation methodology for detailed 3D core power distribution, using in-core detector signals and core monitoring constants such as the 3D Coupling Coefficients (3DCC), node power fraction, and pin-to-node factors. Also, the calculation method for several core safety parameters is introduced. The core monitoring constants for the real core state are promptly provided by the core design code and on-line MASTER (Multi-purpose Analyzer for Static and Transient Effects of Reactors), coupled with the core monitoring program. through the plant computer, core state variables, which include reactor thermal power, control rod bank position, boron concentration, inlet moderator temperature, and flow rate, are supplied as input data for MASTER. MASTER performs the core calculation based on the neutron balance equation and generates several core monitoring constants corresponding to the real core state in addition to the expected core power distribution. The accuracy of the developed method is verified through a comparison with the current CECOR method. Because in all the verification calculation cases the proposed method shows a more conservative value than the best estimated value and a less conservative one than the current CECOR and COLSS methods, it is also confirmed that this method secures a greater operating margin through the simulation of the YGN-3 Cycle-1 core from the viewpoint of the power peaking factor for the LPD and the pseudo hot pin axial power distribution for the DNBR calculation.

• 한국수자원학회논문집
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• 제44권6호
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• pp.439-447
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• 2011

This study aims to test the feasibility of combined use of EFDC (Environmental Fluid Dynamics Code) hydrodynamic model and WASP7.3 (Water Quality Analysis Program) model to improve accuracy of water quality predictions of the Yongdam Lake, Korea. The orthogonal curvilinear grid system was used for EFDC model to represent riverine shape of the study area. Relationship between volume, surface and elevation results were checked to verify if the grid system represents morphology of the lake properly. Monthly average boundary water quality conditions were estimated using the monthly monitored water quality data from Korean Ministry of Environment DB system. Monthly tributary flow rates were back-routed using dam discharge data and allocated in proportion to each basin area as direct measurements were not available. The optimum number of grid system was determined to be 372 horizontal cells and 10 vertical layers of the site for 1 year simulation of hydrodynamics and water quality out of iterative trials. Monthly observed BOD, TN, TP and Chl-a concentrations inside the lake were used for calibration of WASP7.3 model. This study shows that EFDC and WASP can be used in series successfully to improve accuracy in water quality modeling. However, it was observed that the amount of data to develop inflow water quality and flow rate boundary conditions and water quality data inside lake for calibration were not enough for accurate modeling. It is suggested that object-oriented data collection systems would be necessary to ensure accuracy of EFDC-WASP model application and thus for efficient lake water quality management strategy development.

• 한국임상약학회지
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• 제24권4호
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• pp.255-264
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• 2014

Objective: The aims of this study are to investigate the total volume of prescribed medicines against Alzheimer's disease (AD) and the trends of usage by analyzing the claims-data from the Korea National Health Insurance Service. Method: The demographic and claims-data were included the major AD treating medicines such as donepezil, galantamine, rivastigmine and memantine, and analyzed during the period of 2010~2012. The assessing criteria were gender, age, habitation, types of medical institution, code of ingredients, outcomes of treatment, volume and amount of claims, and the numbers of patients with dementias. After trimming the data, it were analyzed by the market size, demographic traits, characteristics of medical service, characteristics of each anti-AD medicine, etc. Results: Among the chosen 4 medicines, donepezil had the top prescription volumes. Most prevalent prescribing preparations of donepezil were conventional types. However, among the non-conventional types, oro-dispersible formulation is the fast increasing one in both volume and growth rate. This specialized preparations to improve both toleration and adherence, tend to being prescribed generally at the tertiary medical institutions. While the younger patients with mild-to-moderate AD mostly treated by expensive medicines in resident at the tertiary hospitals, the rest older patients with severe AD have been treated non-expensive one at long-term care facilities. Conclusion: AD is a chronic illness therefore, long-term use of therapeutic medications are highly important. If an anti-AD treatment was applied steadily in the earlier stages, it would be achieved not only improving the quality of life of patient but also reducing the expenses in the medical and nursing cares. As the socioeconomical impacts of AD is expanding, healthcare professionals need to aware the importance of pharmacotherapy and to improve sociopolitical fundamentals.

• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.11-19
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• 2010

The performance of the crossover system of a centrifugal compressor stage consisting of static components of $180^{\circ}$ U-bend, return channel vanes and exit ducting with a $90^{\circ}$ bend is investigated. This study is confined to the assessment of performance of the crossover system by varying the shape of the return channel vanes. For this purpose two different types of Return Channel Vanes (RCV1 and RCV2) were experimentally investigated. The performance of the crossover system is discussed in terms of total pressure loss coefficient, static pressure recovery coefficient and vane surface pressure distribution. The experimentation was carried out on a test setup in which static swirl vanes were used to simulate the flow at the exit of an actual centrifugal compressor impeller with a design flow coefficient of 0.053. The swirl vanes are connected to a mechanism with which the flow angle at the inlet of U-bend could be altered. The measurements were taken at five different operating conditions varying from 70% to 120% of design flow rate. On an overall assessment RCV1 is found to give better performance in comparison to RCV2 for different U-bend inlet flow angles. The performance of RCV2 was verified using numerical studies with the help of a CFD Code. Three dimensional sector models were used for simulating the flow through the crossover system. The turbulence was predicted with standard k-$\varepsilon$, 2-equation model. The iso-Mach contour plots on different planes and development of secondary flows were visualized through this study.

• KIEAE Journal
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• 제16권4호
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• pp.71-77
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• 2016

Purpose : The energy saving in a residential building (apartment) sector is known as one of the effective solution of energy reduction. In South Korea, the government has recently reinforced regulations associated with the energy performance of buildings. However, there is a lack of research on the methods for the energy performance diagnosis that is used to analyze the wall thermal performance of the existing apartments. Because a reliable diagnosis is necessary to save the building energy, this study analyzed wall thermal performance of an existing apartment in Seoul. Method : This paper applied two methods for analysis of the thermal insulation performance; HFM(Heat Flow Meter) method and ASTR(Air-Surface Temperature Ratio) method. The HFM method is suggested by ISO9869-1 code to measure the thermal performance. The ASTR method is proposed by this study for the simplified In-situ measurement and it uses three temperature data (interior wall surface, interior and exterior air) and the overall heat transfer coefficient. This study conducted the experiment of an existing apartment in Seoul using these methods and analyzed the results. Furthermore, the energy simulation tool of the building was used to suggest retrofit of the building based on the results of measurements. Result : The error rate of HFM method and ASTR method was analyzed in about 17 to 20%. As the results of comparison between the initial design values of the wall and the measured values, the 26% degradation of insulation thermal performance was measured. Lastly, the energy simulation tool of the building shows 10.8% energy savings in accordance with the construction of suggested retrofit.

• 한국통신학회논문지
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• 제27권6C호
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• pp.625-631
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• 2002

본 논문에서는 유한 필드 GF(2")상에서 모듈러 곱셈 A(x)B(x) mod G(x)를 수행하는 MSB 우선 디지트 시리얼곱셈기를 설계하였다. 이를 위하여 GF(2")상에서 MSB 우선 곱셈 알고리즘으로부터 자료 의존 그래프를 구하고, 이를 이용하여 효율적인 디지트 시리얼 시스톨릭 곱셈기를 설계한다. 설계된 곱셈기에 대한 VHDL 코드를 구하고 시뮬레이션을 거친 후 FPGA 로 구현한다. 구현된 곱셈기는 디지트의 크기를 L로 설정했을 경우 연속적인 입력 데이터에 대해 [m/L) 클럭 사이클 비율로 곱셈의 결과를 출력한다. 본 연구에서 구현된 곱셈기를 기존의 곱셈기와 비교 분석한 결과 시간 및 공간 복잡도가 감소되었으며, 간단한 구조로서 데이터 처리 지연시간을 줄일 수 있다. 또한 본 연구에서 제안한 구조는 단 방향의 신호 흐름 특성을 가지고 있으며, 매우 규칙적이기 때문에 m과 L에 대해 높은 확장성을 가진다.