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오피스 임대료 하락기 및 상승기의 임대료 결정모형 회귀모수의 변화 - 서울시 강남과 도심권역을 중심으로 -
최종근,김서경,Choi, Jonggeun,Kim, Suhkyong 한국지역학회 2018 지역연구 Vol.34 No.1
본 논문은 임대료시장의 주기변화에 따른 헤도닉 모형의 임대료 결정요인의 영향력 변화를 분석하였다. 임대료지수를 구축하여 분석한 결과 금융위기가 전환점이 되어 서울시 임대료 시장이 하락기와 상승기로 구분됨을 밝혔으며 주기에 따른 헤도닉 모형의 특성변수의 회귀모수 변화를 고찰하였다. 분석은 강남오피스와 도심오피스로 구분하여 실시하였으며 권역에 상관없이 일관된 변화를 보인 개별회귀모수로서는 토지가격, 지하철역에서의 거리, 건물규모, 건물연한 및 전환이율로 밝혀졌다. 상승기에는 건물의 규모가 클수록 임대료가 높아지는 경향이 있으며 건물이 오래될수록 임대료 하락요인으로의 영향이 커지는 경향이 있는 것으로 나타났다. 전환이율 역시 임대료에서 차지하는 비중이 상승기에 높아짐을 보여준다. 토지가격의 영향은 줄어들고 교통편의성의 장점은 약해지고 있어 상승기에는 지리적 이점의 영향력이 감소하고 건물 특성의 영향력이 상대적으로 커지는 실증적 증거를 제시하였다. This paper empirically investigates time-varying regression parameter of hedonic price model for Seoul office rental market in distinct periods of a market cycle. Office rental index is constructed and the index indicates that the global financial crisis differentiates the analysis period into decline stage and recovery stage. Pre-crisis period is classified into decline stage and post-crisis is classified into recovery stage. Structural break-point test suggests structural change of hedonic model of rent determinants occurred in 2008. Evidence indicates that individual regression parameters of hedonic price model for decline stage are significantly different from those for recovery stage. Changes in the regression parameters of land price, distance to metro, building size, building age, and conversion rate are consistent. In recovery stage, the effect of locational advantage on office rent decreases whereas the effect of building characteristics on the rent increases.
여울-소 출현 복원을 통한 다양한 어종의 서식처 변화 연구
최흥식(Heung Sik Choi),최종근(Jonggeun Choi),최병웅(Byungwoong Choi) 응용생태공학회 2020 Ecology and resilient infrastructure Vol.7 No.1
본 연구는 복원기법을 다양하게 조성하였을 때 어류의 서식처의 변화를 파악하기 위하여 물리서식처 모의를 수행하였다. 대상 구간은 원주천이며, 대상 어종은 돌고기, 피라미, 참갈겨니를 대상으로 하였다. 흐름 분석은 2차원 모형인 River2D 모형을 사용하였으며, 서식처 분석은 서식처 적합도 곡선을 이용하여 서식처의 양과 질을 산정하는 서식처 적합도 모형을 사용하였다. 생태학적으로 적합한 여울-소 출현에 따른 서식처의 변화를 확인하기 위하여 조성 구간을 50 m, 100 m, 200 m, 300 m으로 설정하였다. 그 결과 대상 어종별로 약간의 차이는 발생하였지만, 여울-소 복원기법을 200 m 구간으로 설정하였을 때 서식처가 현상태와 비교하였을 때 가중가용면적이 약 53% 향상되는 것으로 나타났다. The present study aimed to investigate the impact of the restoration of the restoration technique on fish habitat using a physical habitat simulation in the Wonju-cheon Stream, Korea. The target species were Pungtungia herzi, Zacco platypus, and Zacco Koreanus, a dominant and sub-dominant species in the Wonju-cheon Stream. The River2D model was used for the computation of the flow and the habitat suitability index model was used to estimate the quality and quantity of habitat using habitat suitability curve. To assess the impact of pool-riffle sequence on change of fish habitat, this present study conducted using the each representative distance, namely, 50 m, 100 m, 200 m, and 300 m. Simulation results indicated that the pool-reffle sequence significantly increased the habitats for the target species than the result without considering pool-riffle sequence. On average, 53% of the Weighted Usable Area (WUA) increased due to pool-riffle sequence in the study area.
SI 엔진의 스로틀 밸브에서 유동장 특성에 대한 실험해석
김성초,김철,최종근,이석정,Kim, Sungcho,Kim, Cheol,Choi, Jonggeun,Lee, Seokjeong 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.7
Experimental investigations on the flow characteristics of downstream region of a butterfly valve, which is used in SI engine, have been conducted according to Reynolds number and valve angle. Measurement programs of the flowfield using x-type of hotwire anemometry include the mean and fluctuating velocity, turbulnet intensity, shear stress, power spectrum and pressure loss coefficient. Experimental results show that flow characteristics and independent of relatively high Reynolds number; 60,000 and 80,000. It is also seen that streamwise mean velocities have relatively large velocity gradient around the butterfly valve with increasing the valve opening angle and this trend appears even in the far downstream region. The distributions of turbulent intensity and shear stress show irregular behavior regardless of the valve opening angle and those of the case of the valve opening angle of 45°are the largest. The pressure loss coefficient of the body surface of the throttle valve increases mildly with the increase of Reynolds number and increases rapidly with the reduction of the valve opening angle.
해저생산플랜트 설계를 위한 흐름 견실성 문제에 대한 소고
조경남(Gyungnam Jo),이성근(Sung Geun Lee),장광필(Kwang Pil Chang),최종근(Jonggeun Choe),김윤호(Yunho Kim),최항순(Hang S. Choi) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
Design and operating guidelines for subsea O&G (oil & gas) production systems have been developed to ensure the control of hydrates, wax and other solids, which may impede flow. System designs are primarily driven by the need to avoid the formation of a hydrate plug in any portion of the system. Remediation of hydrate plugs may require system shut-down for weeks or even months. The design and operating guidelines for controlling of solids and hydro-dynamic slugging in the subsea systems are aimed to secure the flow assurance process.
조경남(Gyungnam Jo),이성근(Sung Geun Lee),장광필(Kwang Pil Chang),최종근(Jonggeun Choe),김윤호(YunhoKim),최항순(HangS.Choi) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
AbstractHydrocarbon processing on the seabed rather than on offshore platforms is an innovative and challenging concept as the water depth of offshore oil fields increases. The recent achievement of subsea technology enables the development of marginal fields in harsh circumstances - long offsets, deepwater, HP/HT, and small reservoir pockets. However, there are still many problems to be solved. On the near horizon, for example, one of important issue is how to improve the well recovery and how to replace the wet-tree production systems. Future challenges include new production systems in ultra-deep water under harsh environment and in ecologically sensitive regions with few local host facilities.