하모니 검색 알고리즘을 이용한 포트홀 발생 개수 예측 모형

김도완,이상염,김동호,Kim, Dowan,Lee, Sangyum,Kim, Dongho 한국건설관리학회 2014 한국건설관리학회 논문집 Vol.15 No.4

최근 급격한 기후 변화에 관련하여 아스팔트 도로의 손상이 다발적으로 발생하고 있다. 이러한 현상을 해결 및 방지하기 위해서 세계 각국에서 다양한 연구를 수행하고 있다. 이와 관련하여, 본 연구에서는 서울시에서 발생하는 포트홀 수에 대한 예측모형을 개발하였다. 예측모델을 개발함과 동시에 다양한 독립변수 중 실제 포트홀 발생에 영향을 미치는 요소를 파악하기 위해 경험적인 방법과 통계적인 방법을 활용하였다. 예측모형은 BHS (Basic Harmony Search) 알고리즘을 이용하여 결정하였으며, 기후자료와 교통량 자료 및 포트홀 발생 자료를 기반으로 예측이 이루어진다. 하모니 검색 알고리즘을 이용하여 예측모델을 결정하는 과정에서 PAR(Pitch Adjusting Rate)과 HMCR(Harmony Memory Considering Rate)의 영향을 파악하기 위해 이 값을 변화시키며 적합성을 판단하였다. 예측모델은 Training Data(2011년, 2012년 및 2013년 자료)로 인해 구성되며, 결정된 모델의 적합성을 판단하기 위해 Testing Set에 적용하도록 하였다. 기본적인 예측모델의 적합성 판단은 RMSE(Root Mean Squared Error), MAE(Mean Absolute Error), 결정계수(Coefficient of Determination)를 이용하도록 하였다. A bunch of asphalt roads have been damaged frequently in relation to the rapid climate change. To solve and prevent this type of problems, many nationalities in the world have performed various researches. In this regard, the objective of this study is to develop prediction model as to the number of potholes occurred in seoul. At the same time, we have utilized empirical and statistical approaches in order for us to identify factors which is affecting the actual occurrence. The predictive model was determinded by using BHS (Basic Harmony Search) algorithm. Prediction was based on the weather and traffic data as well as data occurrence data of porthole. To assess the influences which are PAR(Pitch Adjusting Rate) and HMCR(Harmony Memory Considering Rate), we determined suitability by changing the values. In the process of the determining a predictive model, the predictive model composed Training data (2011, 2012 and 2013yrs data). To determine the suitability of the model, we have utilized Testing Set (2009 and 2010 yrs data). The suitability of the basic prediction model has been from RMSE(Root Mean Squared Error), MAE(Mean Absolute Error) and Coefficient of determination.

한국형 도로포장 설계 프로그램의 소석회 사용 아스팔트 혼합물 특성 적용

김도완,이상염,문성호,Kim, Dowan,Lee, Sangyum,Mun, Sungho 한국도로학회 2015 한국도로학회논문집 Vol.17 No.4

PURPOSES : The hydrated lime-modified asphalt, which improves moisture resistance, is normally used for pavements to reduce the number of potholes. However, the method of applying the material properties of the lime-modified asphalt mixture for use in pavements is not covered in the Korean Pavement Research Program (KPRP). The objective of this research is to find a method for the design application of lime-modified asphalt's material properties to the KPRP. METHODS: The section for test design is selected in some conditions which are related to the level of design regarding Annual Average Daily Traffic (AADT). To define the application methods of hydrated lime in the KPRP, the models of fatigue, rut and international roughness index (IRI) are determined based on the M-EPDG test results from some earlier research results. Moreover, it is well known that dynamic moduli of the unmodified mixture are not different from those of the lime-modified mixture. RESULTS: The performance results of hydrated lime-modified asphalt pavement were not very much different from those of the unmodified pavement, which meant the limited design regulations regarding fatigue failure, rutting deformation and IRI. CONCLUSIONS: The KPRP uses the weather model from the data for previous 10 years. It implies that the KPRP cannot predict abnormal climate changes accurately. Hence, the predictive weather data regarding the abnormal climate changes are unreliable. Secondly, the KPRP cannot apply the moisture resistance of asphalt mixtures. Therefore, a second level of design study will have to be performed to reflect the influence of moisture. It means that the influence on pavement performance can be changed by the application of hydrated lime in asphalt mixture design.

기준금리 변동에 따른 은행과 저축은행의 예대마진 전략

김도완,Kim, Dowan 한국데이터전략학회 2022 Journal of information technology applications & m Vol.29 No.2

This research confirmed whether banks and saving banks increase their deposit margin under changes in the base rate. This paper has conclusions as follows. First, when the Bank of Korea changes the base rate, deposit rate variable are significant with panel analysis in the total data set and saving banks. This result implies that changes in the base rate affect deposit margin. Second, this study confirmed whether banks and saving banks maximize their deposit margin as base rate changes. As a result, when the Bank of Korea cut the base rate, the deposit margins of banks and saving banks decreased significantly. Still, their deposit margins are not statistically significant in the opposite situation. Therefore, this paper could not find evidence that banks and saving banks behave to maximize their deposit margin. Maybe, this phenomenon can appear because these financial institutions recognize this criticism.

비파괴 충격파 시험을 통한 소석회 첨가 투수성 가열 아스팔트 혼합물의 수분민감성 평가

김도완,문성호,Kim, Dowan,Mun, Sungho 한국도로학회 2015 한국도로학회논문집 Vol.17 No.4

PURPOSES: It is theoretically well known all over the world, that porous hot mixed asphalt (HMA) with hydrated Lime improves moisture and rutting resistance, and reduces pothole occurrence frequency, as well as the life cycle cost (LCC). METHODS : Addictive in the two different formations of the liquid anti-stripping Agent and powder Hydrated-Lime was applied in this investigation in order to obtain relatively clear results according to their types and conditions. Firstly, the moisture conditions were set, and applied to the porous HMA mixtures with hydrated lime (anti-stripping agent). Next, it was followed by a non-destructive test with the application of three freeze-thaw cycles, which were individually carried out thrice to compare the results of the dynamic moduli. Lastly, the hydrated lime effect related to moisture sensibility to porous HMA has been verified through the analysis of the modulus results regarding the change rate of dynamic modulus per n-cycle. RESULTS: It is clear from this investigation, that the dynamic modulus is inversely proportional to the change in temperature, as the graph representing the rigidity of the thermorheologically simple (TRS) material showed gradual decline of the dynamic modulus with the increase in temperature. CONCLUSIONS: The porous HMA mixture with the anti-stripping agent (hydrated Lime) has been found to be more moisture resistant to freezing and thawing than the normal porous HMA mixture. It is clear that the hydrated lime helps the HMA mixture to improve its fatigue resistance.

10KW급 저온수성가스 반응기 특성에 대한 연구

김도완(Dowan Kim),주현철(Hyunchul Ju),김재동(Jeadong Kim),김봉규(Bongkyu Kim),김진욱(Jinwook Kim),손성효(Seunghyo Son),박상현(Sanghyon Park),박달영(Dalyung Park) 한국신재생에너지학회 2014 한국신재생에너지학회 학술대회논문집 Vol.2014 No.11

현대제 170kV GIS DS 조작 Mechanism부 부분방전 발생에 따른 내부점검

김영수(Youngsoo Kim),문병선(Byongseon Moon),김도완(Dowan Kim),한철인(Chulin Han),김대현(Daehyun Kim),김유진(Youjin Kim),김진호(Jinho Kim),이건주(Keonjoo Lee),백동순(Dongsoon Baek),김덕기(Deokgee Kim) 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.7

산화그래핀이 포함된 폴리(N-이소프로필아크릴아미드) 하이드로젤의 기계적, 열적 특성 연구

김도완(Dowan Kim),왕상훈(Sanghoon Wang),이헌상(Heon Sang Lee),윤진환(Jinhwan Yoon) 한국고분자학회 2015 폴리머 Vol.39 No.5

본 연구에서는 산화그래핀(graphene oxide, GO)을 포함하는 폴리(N-이소프로필아크릴아미드)(poly(N-isopropylacrylamide), PNIPAm) 하이드로젤의 기계적 물성을 측정하고, 이를 GO의 분산상태와 다공성 구조의 변화를 통해 설명하였다. 유동계를 이용하여 GO의 함량에 따른 저장탄성률을 측정한 결과, 3 중량%의 GO를 포함할 때 가장 높은 값을 보였다. 주사전자현미경을 통해 3 중량%의 GO를 포함한 시료가 가장 작은 공극을 가지며 다공성 구조가 조밀하게 배열된 것을 확인하였다. 온도에 따른 저장탄성률을 팽윤비와 비교한 결과, PNIPAm/GO 시료가 상변화를 거치며 저장탄성률이 급격하게 증가하는 것을 확인하였고 이를 내부구조의 변화와 연관지어 설명하였다. 본 연구를 통해 GO가 포함된 하이드로젤의 기계적 강도 향상을 확인하였고, 이를 GO의 분산상태에 따른 다공성 내부구조의 변화와 밀접한 관련이 있음을 결론지었다. In this study, we have prepared poly(N-isopropylacrylamide) (PNIPAm) hydrogel containing graphene oxide (GO) by a simple mixing of a solution containing the monomers and aqueous GO through radical polymerization. Mechanical property of the PNIPAm/GO was investigated by measuring storage modulus using a rheometer. PNIPAm containing 3 wt% of GO showed the highest storage modulus among the samples of various GO contents. In this GO content, the exfoliated GO sheets were well dispersed in the hydrogel matrix, enhacing the mechanical property of the hydrogel. We found that the dense porous structure consisted of small channels was formed in the PNIPAm containing 3 wt% of GO. The storage moduli of the PNIPAm/GO hydrogels were rapidly increased near the lower critical solution temperature of the PNIPAm during heating. We concluded that the mechanical property of PNIPAm/GO was closely related to the porous structure of the hydrogels that was affected by the dispersion state of GO in the matrix.

옵션 거래 승수 인상에 따른 유동성 및 프리미엄의 변화

김도완(Dowan Kim),김배호(Baeho Kim) 한국증권학회 2017 한국증권학회지 Vol.46 No.5

한국거래소에서 거래되는 KOSPI200 지수 옵션은 한때 거래량 기준으로 세계 1위 규모를 보이던 금융상품이었으나, 2012년 7월 만기 옵션 거래 승수가 1포인트당 10만 원에서 50만 원으로 상향되면서 거래가 큰 폭으로 위축되었다. 본 연구에서는 이러한 거래 승수 변화로 인해 옵션가격에 반영된 유동성 위험 프리미엄 효과가 실제로 변화하였는지 분석하였다. 실증 분석 결과 다음의 두 가지 결론을 도출하였다. 첫째, 옵션의 내재변동성과 EGARCH 모형으로 추정된 실현변동성의 차이로 정의된 변동성 스프레드의 움직임을 기존 문헌에 보고된 비유동성 변수가 유의하게 설명하는 것으로 나타나 옵션가격에 유동성위험 프리미엄 효과가 반영되어 있음을 확인하였다. 둘째, 변동성 스프레드는 거래 승수 인상 이후 콜옵션과 풋옵션 모두 감소하였으며, 특히 풋옵션에서 이러한 현상이 더욱 강하게 나타났다. 이는 옵션 거래 승수 인상 이후로 시장참여자가 옵션 매도를 할 유인이 줄어들었음을 의미해 매도에 따른 공급 감소와 매수자 중 개인투자자들의 시장진입이 어려워짐에 따라 매수에 의한 수요 감소의 개연성을 가지고 있다. 한편 위험관리 측면에서 헷지 목적으로 풋옵션을 매수하고자 하는 기존 시장참여자들 역시 원하는 시점에 풋옵션을 매수하기 어려워 정확한 헷지 전략을 구현하기가 어려워졌음을 시사한다. KOSPI200 index options market has experienced a substantial liquidity decline after the Financial Services Commission raised the option multiplier to KRW 500,000 (equal to five times prior multiplier) to enhance financial prudence by limiting excessive speculation of retail investors. We examined the impact of the new regulation on the liquidity premium implied by the KOSPI200 index option prices. We find that volatility spread, defined as the discrepancy between the option-implied volatility and the realized volatility of KOSPI200 index, shows a significant inverse relationship against the liquidity premium required by options investors in the market. The volatility spread faced a dramatic contraction grounded by the increase of liquidity premium after the implementation of new regulation. The expansion of liquidity premium became more pronounced for put options rather than call options, as the new multiplier regulation shrank both supply and demand. Risk managers subsequently encountered a difficulty to utilize index put options for their hedging purposes during the period of new multiplier regulation.

직접분사식 가솔린엔진에서 Cooled HP-EGR 시스템 적용에 따른 북미 시험모드 별 차량 연비개선 포텐셜에 관한 연구

김도완(Dowan Kim),김승범(Seungbum Kim),이승환(Sunghwan Lee),임종석(Jongsuk Lim) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5

This paper focuses on the vehicle test result of the US fuel economy test cycles such as FTP75, HWY and US06 with Cooled HP-EGR system on gasoline direct injection(GDI) engine. In general, with EGR system, the mixing exhaust gas with clean air reduces the oxygen concentration in the cylinder charge and increase the heat capacity of the charge mixture. As a result, the combustion temperature drops which is known to improve knocking limit and fuel economy. In this study, 2.4 liters GDI production vehicle was reworked with electrical controlled EGR valve and high efficiency EGR cooler used in diesel serial production. The control algorithm of Cooled HP-EGR system was realized by model based development using SDA-iRPT(internal rapid prototyping) tool from Continental Automotive System. In experiment result, we confirmed that the spark timing was more advanced without knocking and manifold pressure was increased in all cases with EGR system. Furthermore, a positive potential of fuel economy improvement on FTP mode, US06 mode have been shown with EGR system but not for HWY mode where the engine load is quite low and the spark advance is already optimized. Consequently, the fuel economy was increased by maximum 3.3% on FTP mode, 2.7% on US06 mode and decreased by 0.3% on HWY mode respectively with EGR system.

A New Approach to High-Energy-Density Energy Storage Devices: The Feasibility and Potential of Semi-liquid Electrode Configuration

Dowan Kim(김도완),Wang-geun Lee(이왕근) 한국태양에너지학회 2023 한국태양에너지학회 학술대회논문집 Vol.2023 No.4