• 지질공학
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• 제12권2호
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• pp.203-214
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• 2002

벤토나이트의 중금속 흡착에 대한 다양한 실험적 조건을 만족시키기 위하여 박스-벤켄(Box-Benken)의 통계적 모델을 적용하였다. 모델에 의하여 pH, 중금속의 초기농도, HCO$_3$을 변수로 하고, 각 변수에 대한 농도를 3차원으로 설정하여 벳치 실험을 실시하였다. 실험에 선택된 중금속은 Pb, Cu, Zn, Cd 4종이다. 중금속의 흡착거동에 대한 각 변수들의 영향을 표면반응 분석을 통하여 3차원으로 모델링하였다. 중금속의 흡착제거에 중금속의 초기농도와 pH가 거의 비슷한 정도로 큰 영향을 미치고 중탄산은 큰 영향을 미치지 못한다. 중금속간의 흡착경쟁은 Pb>Cu>Zn>Cd의 순서를 보인다. 아울러 pH 변화가 중금속 흡착에 미치는 영향을 실험적 및 열역학적 분석을 통하여 알아보았다. 중금속의 수산화 화합물과 탄산염 복합체의 형태로 침전이 흡착제거에 중요한 변수임이 밝혀졌다. WATEQ4F 열역학 프로그램에 의한 종분포 모델링 결과가 흡착실험결과와 다소 상이함을 보이므로 프로그램의 열역학 자료의 수정이 필요하다.

• 한국건설관리학회논문집
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• 제21권4호
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• pp.30-37
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• 2020

본 연구는 해외건설수주액을 설명하는 다양한 시계열 모형의 비교와 검증을 통해, 예측력 관점에서 가장 적합한 해외건설수주 예측모형을 선택하고(모형선택), 이를 다른 국가의 해외건설수주 예측에도 적용하여 개발된 모형의 보편성을 확인하는데(일반화 검증) 목적이 있다. 연구에는 1981년부터 2019년까지의 연도별 해외건설수주액, 두바이유가 및 국가별 환율 데이터를 활용하였다. 2016~2019년간 예측치와 실측치 간의 오차(MAPE, RMSE, MAE)가 낮고, 2018-2019년간 해외건설수주액 증감여부를 정확하게 맞추는 모형을 선택하였는데, 이러한 기준에 따라 VAR모형이 선택되었다. 이를 활용하여 중국 해외건설수주액을 예측한 결과도 실제와 부합하였다. 이러한 분석 결과는 추후 세계 건설수주 시장 전반을 분석하는 종합적 모형개발 가능성을 시사한다.

• Environmental Engineering Research
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• 제16권2호
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• pp.55-60
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• 2011

The removal of hexavalent chromium from aqueous solutions onto modified holly sawdust was studied at varying initial hexavalent chromium concentrations, adsorbent doses, pHs and contact times. The removal of hexavalent chromium from aqueous solutions increased with increasing adsorbent dosage and contact time. The percentage of hexavalent chromium removed from the aqueous solutions decreased with increasing hexavalent chromium concentration and pH of the solution. The kinetics of the adsorption of hexavalent chromium onto modified holly sawdust was analyzed using pseudo first-order and pseudo second-order models. The pseudo second-order model described the kinetics of adsorption of hexavalent chromium. The Langmuir and Freundlich isotherm models were used for modeling of the adsorption equilibrium data. The Langmuir isotherm model well described the equilibrium data for the removal of hexavalent chromium by modified holly sawdust. The obtained maximum adsorption capacity was 18.86 mg/g at pH 7. The results showed that modified holly sawdust can be used as a low cost adsorbent for the treatment of aqueous solutions containing chromium.

• 한국농공학회지
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• 제45권6호
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• pp.119-127
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• 2003

This paper documents recent efforts to validate the GIS-based hydrologic models, HEC-HMS and HEC-GeoHMS by the US Army Corps of Engineers. HMS and Geo-HMS were used to simulate storm runoff from a small rural watershed, the Balan HS#6. The watershed is 3.85 $\textrm{km}^2$ in size. The watershed topographic, soils, and land use data were processed using the GIS tool fur the models. Input parameters were retrieved and calibrated with the field data. The simulated peak runoff, time to peak, and total direct runoff fer twenty three storms were compared with the observed data. The results showed that the coefficient of determination($R^2$) for the observed peak runoff was 0.95 and an error, RMSE, 3.08 $\textrm{m}^3$/s for calibration stages. In the model verifications, $R^2$ was 0.89 and RMSE 6.79 $\textrm{m}^3$/s, which were slightly less accurate than the calibrated data. The simulated flood hydrographs were well compared to the observed. It was concluded that HMS and GeoHMS are applicable to flood analyses for rural watersheds.

• 산경연구논집
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• 제8권2호
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• pp.5-10
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• 2017

Purpose - The purpose of this paper was to analyze the Chinese government's announcement of the RMB's appreciation on July 1, 2010, and its aim was to ascertain whether the appreciation has affected Chinese export prices by empirically measuring the degree of the exchange rate pass-tough on those prices. Research design, data, and methodology - Using 73 HS trade categories with cross-industry and time-series data, the panel estimation of a fixed-effects model has been applied to measure the degree and stability of any exchange rate pass-through effects. The estimation results show that the export prices of most trade categories were affected by the exchange rate changes. The pass-through effect was generally small, at about -0.485, and statistically significant in most export prices. Results - The empirical results indicate that China would lose its advantage and competitiveness in export if the RMB were appreciated continuously and rapidly because its export goods would no longer operate under strong monopolistic competition. Conclusions - The implications for China's exchange rate policy suggest that it would be better for the RMB to appreciate slowly and gradually rather than radically. It is clear that it would be allow the capital free flow in Chinese overall economic interest to reduce the continuous appreciation pressure on the currency and pave the way for improvements in export distribution competitiveness.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1534-1538
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• 2005

In this paper, we propose a method to detect contours of a face, eyes, and a mouth of a person in the color image in order to make an avatar automatically. First, we use the HSI color model to exclude the effect of various light conditions, and find skin regions in the input image by using the skin color defined on HS-plane. And then, we use deformable templates and genetic algorithm (GA) to detect contours of a face, eyes, and a mouth. Deformable templates consist of B-spline curves and control point vectors. Those represent various shapes of a face, eyes and a mouth. GA is a very useful search algorithm based on the principals of natural selection and genetics. Second, the avatar is automatically created by using GA-detected contours and Fuzzy C-Means clustering (FCM). FCM is used to reduce the number of face colors. In result, we could create avatars which look like handmade caricatures representing user's identity. Our approach differs from those generated by existing methods.

• 한국정보처리학회논문지
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• 제5권5호
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• pp.1083-1097
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• 1998

기존의 GIS(Geographic Information System)는 실세계에 존재하는 지형객체의 속성정보와 공간정보를 취급하는 소프트웨어이다. 이 시스템은 고정된 데이터를 다루기 때문에 시간변이 정보를 저장 관리하여 사용자에게 제공할 수 없으며 제공한다 하더라도 제한적이며 질의 표현과 처리에 많은 어려움을 갖는다. 따라서 이 논문에서는 시간지원 지리정보 시스템을 계층적 접근 방법을 기반으로 기존의 지리정보 시스템이 제공하는 공간에 시간 개념을 확장하여 시간에 따라 변화하는 공간객체의 이력을 지원하는 시공간 통합 데이터 모델을 연구하였다. 즉, 시공간 데이터베이스 구조의 변화에 대한 데이터 구조를 설계하고, 시간변이 공간연산과 이에 따른 시간지원 공간연산자를 제안한다.

• 한국항만경제학회지
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• 제31권3호
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• pp.187-201
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• 2015

본 연구의 목적은 FTA 발효효과가 제89류 교역량 증대에 미치는 영향을 분석하여 조선 산업에 FTA가 미친 영향을 살펴보고자 함에 있다. 이를 위해 HS 89류 교역량 자료를 패널중력모형으로 분석하였다. 분석 결과 종속변수인 제89류 교역량은 FTA 발효효과와 정비례 관계를 나타내었다. 이러한 분석 결과는 FTA 발효 효과 그 자체는 조선 산업의 수출과 수입을 늘리는데 영향을 미쳤다고 볼 수 있다. 우리나라의 조선 산업은 2012년 이후 약화된 경쟁력으로 인하여 선박 수출이 계속해서 감소하고 있다. 이러한 조선 산업은 국가경제에 큰 이바지를 하는 기간산업이자 우리의 주력 수출산업이다. 이러한 조선 산업의 침체를 막고 수출을 증대시키기 위해서는 조선 산업 자체의 경쟁력을 높이기 위한 노력과 함께 FTA를 적극적으로 활용할 수 있는 토대를 마련하는 것이 중요하다.

• Computers and Concrete
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• 제15권1호
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• pp.55-71
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• 2015

This paper presents a novel harmony search (HS)-based data-driven single input rule modules (SIRMs)-connected fuzzy inference system (FIS) for the prediction of stress in externally prestressed tendon. The proposed method attempts to extract causal relationship of a system from an input-output pairs of data even without knowing the complete physical knowledge of the system. The monotonicity property is then exploited as an additional qualitative information to obtain a meaningful SIRMs-connected FIS model. This method is then validated using results from test data of the literature. Several parameters, such as initial tendon depth to beam ratio; deviators spacing to the initial tendon depth ratio; and distance of a concentrated load from the nearest support to the effective beam span are considered. A computer simulation for estimating the stress increase in externally prestressed tendon, ${\Delta}f_{ps}$, is then reported. The contributions of this paper is two folds; (i) it contributes towards a new monotonicity-preserving data-driven FIS model in fuzzy modeling and (ii) it provides a novel solution for estimating the ${\Delta}f_{ps}$ even without a complete physical knowledge of unbonded tendons.

• 무역학회지
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• 제44권3호
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• pp.289-305
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• 2019

Recently, each country has been using non-tariff barriers (Non-Tariff Barriers, NTB) as a new protection trade policy. In particular, TBT lies at the center of NTB. In this context, we examine the impact of Technical Barriers to Trade (TBT) on Korea's exports to ASEAN. Using 10-year statistics from 2007 to 2016 that came into effect with the ASEAN FTA, we analyze the impact of TBT on the Korean exports in the electrical machinery industry (HS85), which accounts for more than 30 percent of Korea's total exports to ASEAN. The results of the empirical analysis using a gravity model showed significant and positive effects in the variables of GDP and real effective exchange rate in each ASEAN country on Korea's exports to ASEAN. As expected, the tariff rate has a negative effect. As for TBT, the key variable of this study, the results are as follows. Although many previous studies reported that TBT has negative impacts on exports, this study could not find any significant impact of TBT and found that Korea's exports of electrical machinery to ASEAN countries are not affected by TBT. Various implications of these results are suggested.