• 한국컴퓨터정보학회논문지
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• 제25권8호
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• pp.151-157
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• 2020

소년 범죄를 예방 하는 방안으로는 범죄자를 처벌하는 방안을 우선 고려할 수 있다. 그러나 범죄자 처벌이 능사는 아니다. 더구나 판단력이 부족한 특성이 있는 소년기의 특성을 고려하면 처벌 위주 보다는 개선 교육을 제공함으로써 당사자로 하여금 범죄자에게 사회가 가하는 낙인을 피할 수 있게 할 수 있으며 사회 복귀를 통해서 사회적 기술도 터득할 수 있을 뿐만 아니라 사회 발전에 기여할 수 있는 직업 능력을 계발할 수 있는 기회를 상실하지 않을 수 있을 것이다. 소년범죄예방을 위한 해외사례를 종합해보면 미국의 종합전략프로그램 중 배치 매트릭스를 통해서 소년의 요보호성 정도와 위험 노출 정도를 종합적으로 평가하고 범죄 경력의 진행을 고려하여 그에 상응하는 제재를 가하고 그 제재의 정도를 세분화해서 적용하고 있다. 청소년 범죄 예방의 주체로는 사법기관의 독자적인 업무로 보기보다는 가정·학교·지역사회·사법기관 공동으로 청소년 범죄 예방의 주체가 되어야 할 것이다.

• International Journal of Fluid Machinery and Systems
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• 제8권3호
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• pp.209-219
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• 2015

A robust multi-fidelity optimization methodology has been developed, focusing on efficiently handling industrial runner design of hydraulic Francis turbines. The computational task is split between low- and high-fidelity phases in order to properly balance the CFD cost and required accuracy in different design stages. In the low-fidelity phase, a physics-based surrogate optimization loop manages a large number of iterative optimization evaluations. Two derivative-free optimization methods use an inviscid flow solver as a physics-based surrogate to obtain the main characteristics of a good design in a relatively fast iterative process. The case study of a runner design for a low-head Francis turbine indicates advantages of integrating two derivative-free optimization algorithms with different local- and global search capabilities.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.604-615
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• 2019

Single-user spectrum sensing is susceptible to multipath effects, shadow effects, hidden terminals and other unfavorable factors, leading to misjudgment of perceived results. In order to increase the detection accuracy and reduce spectrum sensing cost, we propose an adaptive cooperative sensing strategy based on an estimated signal-to-noise ratio (SNR). Which can adaptive select different sensing strategy during the local sensing phase. When the estimated SNR is higher than the selection threshold, adaptive double threshold energy detector (ED) is implemented, otherwise cyclostationary feature detector is performed. Due to the fact that only a better sensing strategy is implemented in a period, the detection accuracy is improved under the condition of low SNR with low complexity. The local sensing node transmits the perceived results through the control channel to the fusion center (FC), and uses voting rule to make the hard decision. Thus the transmission bandwidth is effectively saved. Simulation results show that the proposed scheme can effectively improve the system detection probability, shorten the average sensing time, and has better robustness without largely increasing the costs of sensing system.

• 대한기계학회논문집B
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• 제27권12호
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• pp.1667-1672
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• 2003

In contrast to the high demand for MEMS devices, microflow analysis is not feasible even for single-phase flow with conventional Navier-Stokes equation because of non-continuum effect when characteristic dimension is comparable with local mean free path. DSMC is one of particle based DNS(Direct Numerical Simulation) methods that uses no continuum assumption. In this paper, gas flow in microchannel is studied using DSMC. Interfacial shear and flow characteristics are observed and compared with the results of gas flow that is in contact with liquid case and solid wall case. The simulation is limited to the case of equilibrium steady state and evaporation/condensation coefficient is assumed to be the same and unity. System temperature remains constant and the interfacial shear appears to be small compared to the result with solid wall. This is because particles evaporated and reflected from the liquid surface form high density layer near the interface with liquid flow.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.13-20
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• 1995

Effects of thermal annealing on the dielectric/piezoelectric properties of $Pb(Zn, Mg)_{1/3}Nb_{2/3}O_3-PbTiO_3$ ceramics (PZMNPT) with Zn/Mg=6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Both the relative dielectric permittivity ($\varepsilon$r)and the piezoelectric constant($d_33$)/electromechanical coupling constant ($k_p$)were increased by thermal annealing ($800^{\circ}$~$900^{\circ}C$) after sintering at $1150^{\circ}C$ for 1 hr. Based on the dielectric analysis using the series mixing model and the concept of a random distribution of the local Curie points, the observed improvements in the dielectric and piezoelectric properties of PZMN-PT were interpreted in terms of the elimination of PbO-rich amorphous intergranular layers(~1nm) induced by thermal annealing. A concrete evidence of the presence of amorphous grain-boundary layers in the unannealed (as-sintered) specimen was obtained by examining the structure of intergranular region using a TEM.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1528-1535
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• 2009

Characteristics of R-22 and R-134a two-phase vaporization in horizontal small tubes were investigated experimentally. In order to obtain the local heat transfer coefficients, the test was ran under heat flux range of 10 to $40\;kW/m^2$, mass flux range of 200 to $600\;kg/m^2s$, saturation temperature range of 5 to $10^{\circ}C$, and quality up to 1.0. The test section, which was made of stainless steel tube and heated uniformly by applying an electric current to the tube directly, have inner tube diameters of 0.5, 1.5 and 3.0 mm, and lengths of 0.33 and 2.0 m. The effects on heat transfer coefficient of mass flux, heat flux and inner tube diameter were presented. The experimental heat transfer coefficients were compared with the predictions using existing heat transfer coefficient correlations. A new boiling heat transfer coefficient correlation based on the superposition model, with considering the laminar flow, was developed.

• 설비공학논문집
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• 제21권9호
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• pp.483-495
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• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed downstream of the high pressure turbine extraction stream line-inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes operation of experience and numerical analysis composed similar condition with real high pressure feedwater heater. This study applied squared, curved and new type impingement baffle plates to feedwater heater same as previous study. In addition, it shows difference of pressure distribution and value between single phase and two phase based on experience and numerical analysis.

• Applied Microscopy
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• 제52권
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• pp.14.1-14.10
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• 2022

An electron probe X-ray microanalyzer (EPMA) is an essential tool for studying chemical composition distribution in the microstructure. Quantifying chemical composition using standard specimens is commonly used to determine the composition of individual phases. However, the local difference in chemical composition in the standard specimens brings the deviation of the quantified composition from the actual one. This study introduces how to overcome the error of quantification in EPMA in the practical aspect. The obtained results are applied to evaluate the chemical com position of retained austenite in multi-phase steel. Film-type austenite shows higher carbon content than blocky-type one. The measured carbon contents of the retained austenite show good coherency with the calculated value from the X-ray diffraction.

• 한국실내디자인학회논문집
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• 제19권5호
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• pp.95-104
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• 2010

One of 21st century's main paradigms is a 'Culture', and people started to express their 'cultural desires and demands' regarding public environments. Accordingly central and local governments are paying attention to these demands from their citizens and trying to establish the policies to meet these needs. This research is done to suggest the strategy programming model to support the executions of culture-centered public designs which are based on the local resources and identities. The entire research contains three sub-topics. First topic is setting the prototype phases of strategy programming. Second topic is analyzing the associated indices for each prototype phase. Third topic is suggesting Matrix Model in which the prototype phases and their associated indices are linked. Among three topics, this paper deals with the first one - the prototype phases of strategy programming. It studies this subject in relation with Place Marketing which emphasizes the local resources and identities. The prototype phases are comprised of 3 steps for Place Strategy and 4 steps for Marketing Strategy. Place Strategy should be considered prior to Marketing Strategy because in culture-centered public design, locality has priority over other concerns. The phases for Place Strategy includes 'Resource_analyzing of local resources', 'Mission_setting a purpose', and 'Targeting_segmenting target groups'. The phases for Marketing Strategy involves 'Organization_instituting the main body and/or partnership', 'Image Positioning_setting an unique local image', 'Point_realizing the product', and 'Channel_deciding the sales promotion tools'.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1867-1870
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• 2005

The celestial navigation is one of alternatives to GPS system and can be used as a backup of GPS. In the celestial navigation system using more than two star trackers, the vehicle's ground position can be solved based on the star trackers' attitude information if the vehicle's local vertical or horizontal angle is given. In order to determine accurate ground position of flight vehicle, the high accurate local vertical angle measurement is one of the most important factors for navigation performance. In this paper, the Earth geophysical deflection was analyzed in the assumption of using the modern electrolyte tilt sensor as a local vertical sensor for celestial navigation system. According to the tilt sensor principle, the sensor measures the tilt angle from gravity direction which depends on the Earth geoid surface at a given position. In order to determine the local vertical angle from tilt sensor measurement, the relationship between the direction of gravity and the direction of the Earth center should be analyzed. Using a precision orbit determination software which includes the JGM-3 Earth geoid model, the direction of the Earth center and the direction of gravity are extracted and analyzed. Appling vector inner product and cross product to the both extracted vectors, the magnitude and phase of deflection angle between the direction of gravity and the direction of the Earth center are achieved successfully. And the result shows that the angle differences vary as a function of latitude and altitude. The maximum 0.094$^{circ}$angle difference occurs at 45$^{circ}$latitude in case of 1000 Km altitude condition.