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심해저 망간단괴에서 추출되는 금속가격 예측 및 적합도 분석
권석재,정선영 한국해양과학기술원 2014 Ocean and Polar Research Vol.36 No.4
The development of deep seabed manganese nodules has been carried out with the aim of commercial development in 2023. It is important to forecast the price of the four metals (copper, nickel, cobalt, and manganese) extracted from manganese nodules because price change is a criterion for investment decision. The main purpose of the study is to forecast the price of four metals using the ARIMA model and VAR model, and calculate the MAPE to compare a goodness-of-fit between the two models. The estimated results of the two models reveal statistical significance and are in keeping with economic theory. The results of MAPE for goodness-of-fit show that the VAR model is between 0.1 and 0.2, and the ARIMA model is between 0.4 and 0.6. That is, the VAR model is better than the ARIMA model in forecasting changes in the price of metals.
Status and efficiency of Wastewater sea outfalls in Korea
권석재,서일원,이중우,김영도 한국항해항만학회 2005 한국항해항만학회지 Vol.29 No.9
This study provided the status and efficiency of the domestic wastewater sea outfalls based on the previous numerical and experimental studies for the analysis of the buoyant discharges from Rosette diffuser in shallow water. The VISJET model and the hybrid model proposed by Kim (2002) can be proper models for the domestic sea outfalls. The experimental results show that the merging height for MBR and MIR depends on the riser diameter and spacing between risers, and the bending characteristics of the buoyant discharges in still ambient water have significant impacts on the dilution. The current wastewater outfall systems in Korea are not effective for the environmental aspect due to the low discharge water depth. The strategies to reduce the contamination near the domestic wastewater outfalls were found to require the sufficient discharge water depth, proper diffuser location considering the tidal currents, enough riser diameter, and sufficient spacing between risers.
Assessment of Noise Externalities by Using Hedonic Price Model
권석재,토마스 글리갈루나스,이문숙,강길모,Kwon, Suk-jae,Grigalunas, Thomas A.,Lee, Moon-Suk,Kang, Gil-Mo The Korean Society of Marine Environment and safet 2008 海洋環境安全學會誌 Vol.14 No.4
소음의 외부효과는 현대사회에서 흔히 발견되는 문제라고 할 수 있다. 소음은 재산적 피해와 같은 외부효과를 발생시키며, 따라서 소음으로 인한 재산피해를 평가하고 효과적 해결책을 찾아내는 연구는 매우 중요하다고 할 수 있다. 분석결과는 통계적 유의성이 있으며, 소음이 재산적 가치에 부정적 효과가 있음을 보여 주고 있다. 모형의 주요 결과로는 소음 단위(데시빌)당 피해액이 추정(5,000 달러${\ast}$로그(dB))되었고, 추정된 소음피해함수(잠재가격함수)는 소음의 한계효과가 감소함을 나타내고 있다. Noise externalities are a ubiquitous problem in modern societies. Research to estimate damages and potential efficient solutions therefore is important for addressing such problems. The results of a hedonic property model show that noise has a statistically significant and quantitatively important negative effect on property values. The key results for the best model show that damages (in year 2000 dollars) are - $5000 ${\ast}$ (ln dB), where dB is noise measured in decibels, allowing for the influence of other factors. Because ln(dB) is a strictly concave funaion, the "noise damage function"exhibits diminishing marginal effects with noise.
권석재,토마스 글리갈루나스,이문숙,강길모 해양환경안전학회 2008 해양환경안전학회지 Vol.14 No.4
소음의 외부효과는 현대사회에서 흔히 발견되는 문제라고 할 수 있다. 소음은 재산적 피해와 같은 외부효과를 발생시키며, 따라서 소음으로 인한 재산피해를 평가하고 효과적 해결책을 찾아내는 연구는 매우 중요하다고 할 수 있다. 분석결과는 통계적 유의성이 있으며, 소음이 재산적 가치에 부정적 효과가 있음을 보여 주고 있다. 모형의 주요 결과로는 소음 단위(데시빌)당 피해액이 추정(5,000 달러*로그(dB))되었고, 추정된 소음피해함수(잠재가격함수)는 소음의 한계효과가 감소함을 나타내고 있다. Noise externalities are a ubiquitous problem in modern societies. Research to estimate damages and potential efficient solutions therefore is important for addressing such problems. The results of a hedonic property model show that noise has a statistically significant and quantitatively important negative effect on property values. The key results for the best model show that damages (in year 2000 dollars) are - 5000 * (ln dB), where dB is noise measured in decibels, allowing for the influence of other factors. Because ln(dB) is a strictly concave funaion, the "noise damage function"exhibits diminishing marginal effects with noise.
영상강 하구언에서 저 산소 층의 제거를 위한 해양방류구의 효과
권석재,조양기,서일원 한국해안,해양공학회 2005 한국해안해양공학회 논문집 Vol.17 No.4
because the anoxic water mass caused mainly by the inflow of fresh water from the sea wall might cause themass reduction of benthos during summer. An ocean outfall system to discharge treated wastewater into seawater may be used as one of the effective and economical ways to eliminate the anoxic layer. The suitable oceanoutfall design is generally proposed for the prediction of the buoyant jet behavior in the near field. Theparameters including CTD and current data are taken into account for more reliable buoyant jet behaviortrajectorial variation of the cross-sectional salinity and DO concentration distribution the calculated buoyantjet boundary according to the tidal periods. On the basis of the results, it is sugested that the single port outfallis a useful system to eliminate the anoxic layer. Proper strategies are also proposed for achieving desirableambient conditions. 여름에기본적으로방조제내부로부터담수의유입으로발생된저산소수괴가저서생물의감소를야기시키기때문에영산강하구언에서저산소층의제거에대한관심이증폭되어왔다. 처리된하폐수를해양에 방류하는해양방류시스템이이러한저산소층을제거하는효율적이고경제적인방법으로이용되어질수있다. 본 연구에서는근역에서방류된부력제트의거동을예측하고자적절한방류구의설계가제안되었다. 신뢰할수있는 부력제트의거동에대한계산을수행하기위하여측정된 CTD 와해류자료등을포함한인자들이고려되어졌다. 조석의주기에따라계산된부력제트의경계내에염분도와용존산소의횡분포의변화를예측하고자여러수치 모형중의하나로 EPA 에의해승인된 CORMIX 1 모형을사용하였다. 수치실험의결과를기준으로볼때단공방류구가저산소층을제거하는데유용한시스템임을알수있었다. 원활한주변수의조건을만족시키기위하여 적절한전략이또한제안되어졌다.