• 정보보호학회논문지
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• 제25권4호
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• pp.817-827
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• 2015

현대인은 스마트폰과 매우 밀접한 관계를 가지고 있으며 이로 인한 수 많은 보안 위협에 노출되어 있다. 실제로 해커들은 스마트폰에 악성 프로그램을 은밀하게 설치하여 장치 이용 제한 및 개인정보 유출 등의 보안 위협을 야기하고 있다. 그리고 그러한 악성 프로그램은 일반적인 프로그램과 다르게 필요 이상의 권한을 요구한다. 본 논문에서는 이 같은 문제를 바탕으로 사용되는 안드로이드 기반 앱들이 요구하는 권한 데이터를 이용하여 주성분 분석(Principle Component Analysis:PCA)과 확률적 K-인접 이웃(Probabilistic K-Nearest Neighbor:PKNN) 방식을 사용하여 효과적으로 악성 프로그램과 일반 프로그램을 분류하고자 한다. 이뿐 아니라 이를 k-묶음 교차 검증(K-fold Croos Validation)을 통해 PKNN의 정확도를 측정하였다. 그리고 일반적으로 사용되는 K-인접 이웃(K-Nearest Neighbor:KNN) 방식과 비교하여, KNN이 분류하기 힘든 부분을 확률적으로 해결하는 PKNN방법을 제안한다. 최종적으로 제안한 방식을 최적화하는 ${\kappa}$와 ${\beta}$ 파라미터를 구하는 것을 목표로 한다. 본 논문에서 사용된 악성 앱 샘플은 Contagio에 요청하여 이용하였다.

• 전산구조공학
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• 제5권3호
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• pp.105-112
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• 1992

원자로 내부구조물의 설계시 필요한 동적응답해석을 위하여 각 구조물의 정확한 진동특성을 파악할 필요가 있다. 한국 표준형 원자력발전소를 위하여 설계된 제어봉집합체 보호구조물은 기존의 설계로 부터 많은 설계변경이 있었고, 또 이 구조물은 튜우브와 얇은 판이 사각격자 형태로 이루어져 있고 연결봉에 의해 고정되는 등 매우 복잡한 형태로 구성되어 있어서 해석과 시험에 의한 진동측정 프로그램을 수행할 필요성이 대두되었다. 따라서 본 논문에서는 진동측정 프로그램의 첫 단계로서 범용구조해석코드인 ANSYS를 이용하여 시험전 해석을 수행하였다. 또 자유도의 수와 얇은 판에 있는 구멍 및 연결봉의 pre-load가 구조물의 자유진동수에 미치는 영향을 검토하였다. 이로부터 결정된 유한요소모델에 대하여 모우드해석을 수행하여 구조물의 고유진동수와 모우드형상을 구하였고, 조화운동해석(Harmonic Analysis)을 행하여 주요모우드에 대한 응답을 측정함으로써 추후에 수행될 진동측정 시험조건 즉 응답측정부위, 측정위치의 수, 측정진동수의 범위 및 가진력의 크기 등을 결정하였다.

• 사상체질의학회지
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• 제8권1호
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• pp.101-186
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• 1996

1. 연구배경 : 사상의학의 가장 중요한 요점은 체질진단이다. 그간 다양한 체질변증에 관한 연구가 있었지만 신체 각부의 형태학적인 연구, 특히 얼굴을 대상으로 한 연구는 거의 전무하였다. 저자들은 그 동안 전일적이고 직관적으로 표현된 동의수세보원의 형태적 묘사를 정량화하여 정리하고, 이 자료를 체질진단의 근거자료로 삼고자 하는 연구의 일환으로 먼저 두안부(頭顔部)의 형태를 태음인 소음인 소양인 별로 그 형상적 특징을 찾아내고자 하였다. 2. 방법 : 1995년 7월부터 1995년 12월까지 경희의료원 부속한방병원 외래환자 및 직원을 대상으로 설문지 및 임상적 치료 경과를 통하여 체질적 경향성이 뚜렷한 대상자를 선별하고 동일촬영 조건을 통하여 얻은 얼굴 사진 중 형태특이자를 제외한 170례의 고경(전두고외 26항목) 방사경(두최대장외 22항목) 및 폭경(안최대폭외 18항목)등 총 69항목을 측정한 후 이를 분석하여 체질별 상이점을 도출하였다. 3. 결과 : 체질별 두면부의 형태학적인 특징을 수치화하여 설명할 수 있게 되었고, 나아가 직관적이고 전일적인 형태를 구체화시킬 수 있는 특징을 도출할 수 있었다. 4. 결론 : 이상의 결과를 이용하여 체질별 각 부분의 형태를 계량화하여 비교 설명하고, 이를 이용하여 체질판별공식을 만들었다.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제4권1호
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• pp.10-21
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• 2001

A new method of laser remote sensing is proposed, based on sensing the sea surface by a narrow laser beam (2-3cm) and analyzing statistically specular reflections. Construction of the angular dependency of the average density of specks versus the aircraft flight horizontal azimuth allows calculation of both intensity and azimuthal properties of the sea surface spectrum. The paper contains the experimental setup and technique, the field measurement data taken onboard an aircraft and the examples of calculated main statistical parameters of sea waves. Their energy-carrying component velocity is found by the mean velocity of an ensemble of specular points at the random sea surface. The surface wave nonlinearity is shown to affect substantially the statistical characteristics measured: mean numbers of specular areas with th given elevation and given slope, arranged along the line of crossing the sea surface by the scanning laser beam. Experimental measurement of a variance in the number of these areas yields a principal possibility to calculate the correlation function of the sea surface without its preliminary modeling.

• Archives of Plastic Surgery
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• 제41권2호
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• pp.163-170
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• 2014

Background The septal cartilage is the most useful donor site for autologous cartilage graft material in rhinoplasty. For successful nasal surgery, it is necessary to understand the developmental process of the nasal septum and to predict the amount of harvestable septal cartilage before surgery. Methods One hundred twenty-three Korean patients who underwent three-dimensional (3D) facial bone computed tomography (CT) were selected for evaluation of the midsagittal view of the nasal septum. Multiple parameters such as the area of each component of the nasal septum and the amount of harvestable septal cartilage were measured using Digimizer software. Results The area of the total nasal septum showed rapid growth until the teenage years, but thereafter no significant change throughout the lifetime. However, the development of the septal cartilage showed a gradual decline due to ossification changes with aging after puberty in spite of a lack of change in the total septal area. The area of harvestable septal cartilage in young adults was $549.84{\pm}151.26mm^2$ and decreased thereafter with age. Conclusions A 3D facial bone CT scan can provide valuable information on the septal cartilage graft before rhinoplasty. Considering the developmental process of the septal cartilage identified in this study, septal surgery should not be performed until puberty due to the risk of nasal growth impairment. Furthermore, in elderly patients who show a decreased cartilage area due to ossification changes, septal cartilage harvesting should be performed carefully due to the risk of saddle nose deformity.

• 환경영향평가
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• 제21권3호
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• pp.391-407
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• 2012

The loss of connectivity and fragmentation of forest landscapes are seriously hindering dispersal of many forest-dwelling species, which may be critical for their viability and conservation by decreasing habitat area and increasing distance among habitats. For understanding their environmental impacts, numerous spatial models exist to measure landscape connectivity. However, general relationships between functional connectivity and landscape structure are lacking, there is a need to develop landscape metrics that more accurately measure landscape connectivity in whole landscape and individual patches. We reviewed functional and structural definition of landscape connectivity, explained their mathematical connotations, and applied representative 13 indices in 3 districts of Seoul having fragmented forest patches with tits, the threshold distance was applied 500m by considering the dispersal of tits. Results of correlation and principal component analysis showed that connectivity indices could be divided by measurement methods whether they contain the area attribute with distance or not. Betweenness centrality(BC), a representative index measuring distance and distribution among patches, appreciated highly stepping stone forest patches, and difference of probability of connectivity(dPC), an index measuring including area information, estimated integrated connectivity of patches. Therefore, for evaluating landscape connectivity, it is need to consider not only general information of a region and species' characteristics but also various measuring methods of landscape connectivity.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.176-183
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• 2005

The exhaust noise of auxiliary engine in ships is directly transmitted to bridge wing with only distance attenuation. It is not easy to find out practical treatment to be applied between exhaust pipe and bridge wing to reduce the transmission of the exhaust noise. In general, therefore, a silencer is fitted to reduce the exhaust noise and correspondingly noise of bridge wing. The silencer should be properly designed under the consideration of the frequency component of the exhaust noise and the required performance such as noise reduction or insertion loss. In general, the gas inside the exhaust pipe flows with high temperature and speed and thus onboard test condition is more adverse than the standard atmospheric condition. In this study, the test method to evaluate silencer performance using a probe microphone is introduced.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.423-433
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• 2004

A large eddy simulation (LES) is performed for turbulent flow in a combustion device. The combustion device is simplified as a cylindrical chamber with sudden expansion. A flame holder is attached inside a cylindrical chamber in order to promote turbulent mixing and to accommodate flame stability. The turbulent sub-grid scale models are applied and validated. Emphasis is placed on the evaluation of turbulent model for the LES of complex geometry. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The calculated Reynolds number is 5000 based on the bulk velocity and the diameter of inlet pipe. The predicted turbulent statistics are evaluated by comparing with the LDV measurement data. The Smagorinsky model coefficients are estimated and the utility of dynamic SGS models are confirmed in the LES of complex geometry.

• 대한기계학회논문집B
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• 제25권7호
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• pp.885-894
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• 2001

A large eddy simulation(LES) is performed for turbulent flow in a combustion device. The combustion device is simplified as a cylinder with sudden expansion. To promote turbulent mixing and to accommodate flame stability, a flame holder is attached inside the combustion chamber. Emphasis is placed on the flow details with different geometries of the flame holder. The subgrid scale models are applied and validated. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The calculated Reynolds numbers are 5000 and 50000 based on the bulk velocity and the diameter of inlet pipe. The predicted turbulent statistics are evaluated by comparing with the LDV measurement data. The agreement of LES with the experimental data is shown to be satisfactory.

• 한국정밀공학회지
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• 제17권5호
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• pp.100-107
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• 2000

The hydraulic couplings have been widely used in industries, automobile, and power-station drives including ships. A mathematical analysis by which the design and application of hydraulic couplings are made is used in conventional design formulae and general roto-dynamic theories. The fluid flow of hydraulic couplings can be considered to have two component, one circumferentially about the coupling axis, and the other passing fluid from the pump to the turbine in the plane of the coupling axis. Tests have been carried out on the full-scale production coupling. The performance test consists of taking measurement of torque of the fluid coupling for three different amount of working fluid inside with various loads to the output shaft. The purpose of this research is to construct the experimental test equipments and to establish a series of performance test for the domestically developed hydraulic couplings, and to obtain experimental results which can be used to improve the performance of the hydraulic coupling and to solve the practical problems confronted in operation.