• 대한기계학회논문집B
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• 제25권2호
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• pp.187-194
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• 2001

Spray impingement and fuel film formation models were developed and incorporated into the computational fluid dynamics code. STAR-CD. The spray/wall interaction process was modeled by considering the change of behaviour with surface temperature conditions and the fuel film formation. We divided the behaviour of fuel droplets after impingement into rebound, spread and splash using the Weber number and the parameter K. The Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. The fuel film formation model was developed by integrating the continuity, Navier-Stokes and energy equations along the direction of fuel film thickness. Validation of the models was conducted using previous diesel spray experimental data and the present experimental results for the gasoline spray impingement. In all the cases, the prediction compared reasonably well with the experimental results. The spray impingement and fuel film formation models have been applied to the spray/wall impingement in high speed direct injection diesel engines.

• 상하수도학회지
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• 제23권2호
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• pp.223-230
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• 2009

Most urban water management systems are becoming vulnerable to flooding and drought due to the climate change (CC), urbanization and energy shortage. Despite of poor water management circumstances caused by extremely uneven annual rainfall and hilly terrain, traditionally we have made a sound and sustainable life based on our own philosophy and technologies which copes with our rigid environment. In this study a new paradigm of rainwater management is suggested and multipurpose and creative rainwater harvesting and management (RWHM) systems are introduced providing several case studies such as rainfall storage drainage (RSD) system, rainwater infiltration facilities and star city RWHM system. This new RWHM paradigm leads Seoul Metropolitan Government (SMG) in the Republic of Korea to change regulations and politics for the integrated RWHM. Finally, RWHM is expected to improve the safety, efficiency, energy consumption of urban water infrastructure, to reduce urban heat island phenomenon and, furthermore, to contribute in finding solutions for worldwide water issues and to adapt CC.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.567-570
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• 2006

A numerical study has been carried out for a solar water heater which consists of double skin solar vacuum tubes. Water is heated as it flows through the coaxial fluid conduit inserted in each tube. The space between the exterior of the fluid conduit and the glass tube is tilled with antifreeze solution. This is to facilitate heat transfer from the solar heated absorber surface to water and to prevent the functional problems due to freezing in frigid weather conditions. A one-dimensional steady state model is fully described which will be used to develop three-dimensional model using STAR-CD. These models could be used efficiently in designing double skin solar collector tubes with different geometrical parameters other than those considered in the present analysis. Results show a good agreement when compared with other experimental data demonstrating the reliability of the one-dimensional model employed.

• 신재생에너지
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• 제8권4호
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• pp.13-20
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• 2012

This paper describes a transformerless static synchronous campensator (STATCOM) system based on cascade H-bridge multilevel inverter with star configuration. It is designed not only for the dynamic and continuous compensation of the reactive power but also for the improvement of power quality of existing wind power plant. Especially, when the induction generator of wind turbine is directly connected to the grid, reactive power are occurred by exiting current. so a reactive power compensation system based on the cascade H-bridge multilevel STATCOM is proposed because the output power quality and controllability of reactive power are required by grid code in many different countries. Using various The proposed reactive power control strategy using a STATCOM is compared with the conventional scheme using fixed-size of capacitor bank through various simulation results.

• 보건의료산업학회지
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• 제5권2호
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• pp.199-208
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• 2011

The purpose of this study is to investigate the strategies and the experiences of 3 university hospitals relevant to environmentally-friendly strategy in their hospitals and to find out the implication for spreading the environmentally-friendly hospital management to other Korean hospitals. The study was progressed from October to November 2010 through the in depth interview with middle manager of the hospitals. Interview items about environmentally-friendly hospital management were selected from ISO 14001, Korean Green Management Certification Scheme, Green Guide Operation Version 2.2 of GGHC, Eco-ChecklistTM, Self-Assessment Tool of "Practice Greenhealth" and some accreditation credits of LEED, BREEAM, GreenStar. The case study result implies that the following strategies are so critical to settle environmentally-friendly hospitals in Korea: 1)understanding about fundamental concept of environmentally-friendly hospital, 2)organizing green teams, 3)purchasing environmentally-friendly goods, 4)benchmarking other successful hospitals, 5)adopting easy & reasonable policy first, 6)managing accumulated data & performance about energy efficiency, and 7)educating the employee about environmentally-friendly hospitals strategies. Hospitals have to keep in pace with the change in government policy and scheme like as GHG & Energy Target Management System, Korean Green Management Certification Scheme, ESCO, and so on for achieving the successful environmentally-friendly hospitals.

• 대한조선학회논문집
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• 제59권6호
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• pp.338-344
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• 2022

Roll moment usually is ignored when analyzing the maneuverability of surface ships. However, it is well known that the influence of roll moment on maneuverability is significant for ships with small metacentric height such as container ships, passenger ships, etc. In this study, a pure roll test is performed to determine the hydrodynamic derivatives with respect to roll motion as added mass and damping. The target ship is an autonomous surface ship designed to carry containers with a small drift and large freeboard. The commercial code of STAR CCM+ software is applied as a specialized tool in naval hydrodynamic based on RANS equation for simulating the pure roll of the ship. The numerical uncertainty analysis is conducted to verify the numerical accuracy. By distinguishing the in-phase and out-of-phase from hydrodynamic forces and moments due to roll motion, added mass derivatives and damping derivatives relative to roll angular velocity are obtained.

• 천문학회보
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• 제45권1호
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• pp.37.1-37.1
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• 2020

Cosmic-ray protons (CRp) are efficiently produced at starburst galaxies (SBGs), where the star formation rate (SFR) rate is high. In this talk, we present estimates of gamma-ray and neutrino emissions from nearby SBGs, M82, NGC253, and Arp220. Inside the starburst nucleus (SBN), CRp are accelerated at supernova remnant (SNR) shocks as well as at stellar wind (SW) termination shocks, and their transport is governed by the advection due to starburst-driven wind and diffusion mediated by turbulence. We here model the momentum distributions of SNR and SW-produced CRp with single or a double power-law forms. We also employ two different diffusion models, where CRp are resonantly scattered off large-scale turbulence in SBN or self-excited waves driven by CR streaming instability. We then calculate gamma-ray/neutrino fluxes. The observed gamma-ray fluxes by Fermi-LAT, Veritas, and H.E.S.S are well reproduced with double power-law distribution for SNR-produced CRp and the CRp diffusion by self-excited turbulence. The estimated neutrino fluxes are <~10-3 of the atmospheric neutrino flux in the energy range of Eneutrino <~100 GeV and <~10-1 of the IceCube point source sensitivity in the energy range of Eneutrino >~60 TeV.

• 한국콘텐츠학회논문지
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• 제8권12호
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• pp.131-140
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• 2008

<쉬리> 이후 주류 한국영화의 특징으로 나타나는 남성중심적 서사에 대한 비판은 영화비평의 한 의제를 구성해왔다. 이러한 서사는 사회적 모순에 대한 상상적 해결책으로 시대적 변화에 대한 반응이다. 본고는 남성중심적 서사의 핵심인 남성정체성 구성을 조건 짓는 토대로서 르페브르의 개념인 '일상'을 제시하고, 일상의 재발견을 통해 정체성 재구성을 모색하고 있는 이준익의 <라디오 스타>와 <즐거운 인생>을 분석한다. 분석의 결과는 양가적이다. 미시사적 개념인 ‘이름없는 사람’, 80년대에 대한 개인적 기억, 일상의 재발견이 정체성 재구성의 가능성을 보여주는 반면 여성의 일상은 서사의 주변부로 밀려나 성별관계를 고착시키기 때문이다. 그러나 기존의 남성중심적 서사와 차별되는 새로운 남성의 서사를 구축하려는 시도의 의미는 시대적 연관성 속에서의 지속적인 탐구를 요구한다.

• 천문학논총
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• 제27권4호
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• pp.311-316
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• 2012

Lyman break Galaxies are galaxies selected in the rest-frame ultraviolet. But, one important and missing information for these Lyman break galaxies is the amount of dust attenuation. This is crucial to estimate the total star formation rate of this class of objects and, ultimately, the cosmic star formation density. AKARI, Spitzer and Herschel are therefore the major facilities that could provide us with this information. As part of the Herschel Multi-tiered Extragalactic Survey, we have began investigating the rest-frame far-infrared properties of a sample of more than 4,800 Lyman Break Galaxies in the GOODS-North fiels. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z <1.6 and one object at z = 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. We have analysed their UV-to-FIR spectral energy distributions using the code cigale to estimate their physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. They also appear to be located in a triangle-shaped region in the $A_{FUV}$ vs. $logL_{FUV}$ diagram limited by $A_{FUV}$ = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. In a second step, we move to the larger COSMOS field where we have been able to detect 80 Lyman break galaxies (out of ~ 15,600) in the far infrared. They form the largest sample of Lyman break galaxies at z > 2.5 detected in the far-infrared. We tentatively name them Submillimeter Lyman break galaxies (S-LBGs).

• 천문학논총
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• 제32권1호
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• pp.245-249
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• 2017

We selected 47 DOGs at z ~ 1.5 using optical R (or r'), AKARI $18{\mu}m$, and $24{\mu}m$ color in the AKARI North Ecliptic Pole (NEP) Deep survey field. Using the colors among 3, 4, 7, and 9µm, we classified them into 3 groups; bump DOGs (23 sources), power-law DOGs (16 sources), and unknown DOGs (8 sources). We built spectral energy distributions (SEDs) with optical to far-infrared photometric data and investigated their properties using SED fitting method. We found that AGN activity such as a AGN contribution to the infrared luminosity and a Chandra detection rate for bump and power-law DOGs are significantly different, while stellar component properties like a stellar mass and a star-formation rate are similar to each other. A specific star-formation rate range of power-law DOGs is slightly higher than that of bump DOGs with wide overlap. Herschel/PACS detection rates are almost the same between bump and power-law DOGs. On the other hand SPIRE detection rates show large differences between bump and power-law DOGs. These results might be explained by differences in dust temperatures. Both groups of DOGs host hot and/or warm dust (~ 50 Kelvin), and many bump DOGs contain cooler dust (${\leq}30$ Kelvin).