• 대한기계학회논문집B
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• 제38권12호
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• pp.1043-1050
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• 2014

물이 채워진 원통 용기를 회전시킨 후 배수하면 일정시간이 지난 후 공기기둥이 발생한다. 용기의 크기, 초기 회전 속도나 교반 속도, 배수구 모양 등의 배수조건에 따라 공기기둥의 발생 여부나 발생시간이 달라진다. 본 연구에서는 2 단으로 구성된 계단형 배수구를 가진 원통 용기에서 물이 배수되는 과정을 수치해석적으로 연구하였다. 하부에 위치한 배수구 1 단은 길이와 반경이 고정되어 있고, 상부에 위치한 2 단은 길이와 반경을 변화시켰다. 2 차원 격자계에 축대칭 조건을 적용하여 원통 용기 내부의 배수유동을 해석하였다. 물과 공기의 자유표면 모양을 추적하여 수위 변화를 관찰하였으며, 배수구 2단의 형상이 공기기둥 발생시간과 내부 유동구조 변화에 미치는 영향을 확인하였다.

• 한국농촌건축학회논문집
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• 제23권4호
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• pp.38-45
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• 2021

In this study, air quality conditions were identified and analyzed in real time, at the same time, living habits and ventilation methods were maintained in the daily life of residents, and thus, this present study focuses on the lifestyles of residents. Previous studies showed a difference from this study, focusing on the study on the effects of changes in indoor air quality on human health according to the indoor air quality process test standards of the Ministry of Environment. Formaldehyde concentrations exceeded all ventilation standards, but satisfied the organic standards of the Ministry of Environment when ventilation devices and air purifiers were activated. As such, it was investigated that a large amount of formaldehyde emission in the condo is initially ventilated, but a certain concentration is maintained. The change in PM2.5 concentration according to the ventilation method showed a clear difference. As a result of simulating indoor air flow during natural ventilation, the effects of wind speed and wind direction affect the flow rate of indoor air, and indoor polluted air is stagnant even in the presence of wind and is not completely discharged. When the risk assessment results are averaged on the day of measurement, the trends of change between adults and children are almost equivalent, but the results address that children are more sensitive to risk than adults.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1686-1692
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• 2012

Densities (${\rho}$), Viscosities (${\eta}$) and ultrasonic speeds (u) of pure acetophenone (AP), propiophenone (PP), $p$-methyl acetophenone ($p$-MeAP), $p$-chloroacetophenone ($p$-ClAP) and those of their binary mixtures with $N$-ethyl aniline ($N$-EA) as a common component, were measured at 303.15 K over the entire composition range. These experimental data were used to calculate the excess volume $V^E$, deviation in ultrasonic speeds ${\Delta}u$, isentropic compressibility $K_s$, intermolecular free length $L_f$, acoustic impedance Z, deviations in isentropic compressibility ${\Delta}K_s$, deviation in viscosity ${\Delta}{\eta}$ and excess Gibbs free energy of activation of viscous flow ($G^{*E}$) at all mole fractions of $N$-ethyl aniline. These parameters, especially excess functions, are found to be quite sensitive towards the intermolecular interactions between component molecules. Theoretical values of viscosity of the binary mixtures were calculated using different empirical relations and theories. The relative merits of these relations and theories were discussed. The experimental results were correlated by using the polynomial proposed by Redlich-Kister equation.

• ETRI Journal
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• 제37권2호
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• pp.406-416
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• 2015

Timing plays a key role in expressing the qualitative aspects of a character's motion; that is, conveying emotional state, personality, and character role, all potentially without changing spatial positions. Temporal editing of locomotion style is particularly difficult for a novice animator since observers are not well attuned to the sense of weight and energy displayed through motion timing; and the interface for adjusting timing is far less intuitive to use than that for adjusting pose. In this paper, we propose an editing system that effectively captures the timing variations in an example locomotion set and utilizes them for style transfer from one motion to another via both global and upper-body timing transfers. The global timing transfer focuses on matching the input motion to the body speed of the selected example motion, while the upper-body timing transfer propagates the sense of movement flow - succession - through the torso and arms. Our transfer process is based on key times detected from the example set and transferring the relative changes of angle rotation in the upper body joints from a timing source to an input target motion. We demonstrate that our approach is practical in an interactive application such that a set of short locomotion cycles can be applied to generate a longer sequence with continuously varied timings.

• 대한기계학회논문집B
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• 제22권5호
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• pp.640-650
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• 1998

Pumping performances of a helical molecular drag dump(MDP) and of a radial MDPs are numerically analyzed by using the direct simulation Monte Carlo (DSMC) method. A helical- and radial-MDP have rotating pumping channels cut on a cylinder and on a disk, respectively. For a helical MDP, the present results agree quantitatively with the previously known numerical results. For radial MDPs, both of the Type 1 (having pumping channels cut on the stationary disk) and of the Type 2 (having pumping channels cut on the rotating disk) are analyzed to predict their performances for various parameters, i.e., the radius of curvature center of the channel wall, the depth of the channel, the clearance between housing and disk, and the rotating speed. The results show that the performance of the Type 2 is superior to that of the Type 1, and that for all types the pumping efficiency decreases as the clearance increases. Also, the radial type MDP has larger leakage losses in the direction of pumping channel than does the helical one.

• 대한기계학회논문집B
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• 제21권1호
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• pp.125-131
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• 1997

The extinction of premixed flames under the influence of stretch is studied numerically. A wide range of fuel (hydrogen, ethylene, acetylene, methane, propane and methanol) and air mixtures are established in an opposed jet and their flame properties such as flame speed, flame thickness, thermal diffusivity, and stretch rate at extinction are computed. Computations are made using several chemical kinetic mechanism (Smooke, Kee et al. and Peters). The major result is that, in contrast to the various previous claims of extinction Karlovitz number varying over three orders of magnitude, it is found to be constant around two for all of the mixtures tested. That is, premixed flames are extinguished when the physical flow time decreases (due to increased stretch rate) to the point where it approximately equals the chemical reaction time. Here the relevant chemical reaction time is not the one computed using the one-dimensional flame properties as originally suggested in the formulation of Karlovitz number, but rather it is the one obtained using the stretched flame properties which fully reflect the effect of straining on the flame structure.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1317-1323
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• 2001

The circumstance is giving the blow against fishermen with the incoming-decreasing and the difficulty of crew's supply & demand and management. In addition, the depression of the external situation like the departure of WTO system and the plan of EEZ proclaim is forcing fishery into improving their fishing condition. By this international and domestic circumstance, development of the sea water cooling apparatus for fish hold storage is demanded sincerely. First of all, we Investigated load characteristics which based on development of sea water cooling system and optimum fish hold storage. The experimental results is as follows. In creasing the speed of compressor and mass blew rate of refrigerant, the temperature of NaCl solution is low. And the load characteristics experiment on fish hold storage outlet is as fellows. As time goes by, increasing the mass flow rate of NaCl solution, temperature difference between inlet and outlet is small in a model of fish hold storage. These results provide many useful informations applicable to an actual design of sea water cooling system and optimum fish hold storage.

• Ocean and Polar Research
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• 제23권4호
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• pp.323-335
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• 2001

Distribution features of foulers attached on 28 ships of 6 main shipping routes (SR) of the Far East Sea Basin were analyzed using various statistical methods. Collections obtained during 1976-1990 in the expeditions by the Institute of Marine Biology were used for the analyses. Samples were taken from the ships during anchorage by SCUBA diving and from dry-docks of Vladivostok ship-repairing yard. In all cases, the distribution patterns of most animals and algal species showed clear contagious patterns. Total biomass of fouling organisms and biomass of attached animals frequently increased along the horizontal direction of ship hulls, from the stem to the sternpost. Animal and algal species were usually located at different sites of the hulls. According to the increasing floating speed, there was, a clear tendency of the displacement in main fouling biomass from the stem to the stem. Any generalizations and deductions concerning the distribution patterns of the foulers from the same SR ships are not always substantiated, but one may see some similarities of the fouler distributions in many cases. Micro-scale turbulence generated by water flow around a ship hull for the distribution of fouling organisms is discussed.

• 산업경영시스템학회지
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• 제17권32호
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• pp.243-253
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• 1994

Work environments have been changed with the advent of new technologies, such as computer technology. The newer technologies, the more changes in our work conditions. However, human cognitive limits can't keep up with the change of work environments. Mental workload has been an important factors in designing modem work environments such as human-computer interaction. Designing man-machine systems requires knowledge and evaluation of the human cognitive processes which control information flow workload. Futhermore, under an urgent situation, human operator may suffer the work stress, work error, and resultant deleterious work performance. To describe the work performance in the urgent work situations, with time stress and dynamic event occurence, a new concept of information density was introduced. For a series of experiments performed for this study, three independent variables(information amount system processing time, information density) were evaluated using such dependent variables as reaction time, number of error, and number of failure. The results of statistical anlysiss indicate that the amount of information effected on all of five dependent measure. Number of failure and number of secondary task score were effected by both amount of information and operational speed of system, but reaction time of secondary task were effected by both amount of information and information density.

• 한국지능시스템학회논문지
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• 제26권5호
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• pp.351-360
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• 2016

Rapid population growth with high living standards and high electronics use for personal comfort has raised the electricity demand exponentially. To fulfill this elevated demand, conventional energy sources are shifting towards low production cost and long term usable alternative energy sources. Hybrid renewable energy systems (HRES) are becoming popular as stand-alone power systems for providing electricity in remote areas due to advancement in renewable energy technologies and subsequent rise in prices of petroleum products. Wind and solar power are considered feasible replacement to fossil fuels as the prediction of the fuel shortage in the near future, forced all operators involved in energy production to explore this new and clean source of power. Presented paper proposes fuzzy logic based Energy Management System (EMS) for Wind Turbine (WT), Photo Voltaic (PV) and Diesel Generator (DG) hybrid micro-grid configuration. Battery backup system is introduced for worst environmental conditions or high load demands. Dump load along with dump load controller is implemented for over voltage and over speed protection. Fuzzy logic based supervisory control system performs the power flow control between different scenarios such as battery charging, battery backup, dump load activation and DG backup in most intellectual way.