평균 해수면 및 최극조위 자료의 이상자료 및 기준고도 변화(Level Shift) 진단

이기섭(Gi-Seop Lee),조홍연(Hong-Yeon Cho) 한국해안해양공학회 2020 한국해안해양공학회 논문집 Vol.32 No.5

부산, 목포 지점의 평균해수면(MSL)과 고극조위, 저극조위 자료의 이상자료 시계열 모델링을 수행하였다. 시계열 모델은 계절성분을 포함하는 SARIMA 모형이며, 일시적인 변화에 해당하는 이상자료(Additive Outlier, AO)와 영구적인 변화를 의미하는 기준고도 변화(Level Shift, LS)를 모델에 포함하였으며, AIC 기준에 의거하여 최적 모델을 선정하였다. 이상자료 모형의 매개변수 추정은 R 프로그램 ‘tsoutliers’ 패키지(‘tso’ 함수)를 이용하였다. 선정 모형을 이용하여 이상자료와 기준고도 변화 진단에 적용한 결과, 부산의 월 단위 고극조위 자료에서 2003, 2012년 발생한 태풍 매미(MAEMI), 산바(SANBA)에 의한 일시적인 수위상승을 65.5, 29.5 ㎝ 정도로 추정하였으며, 목포의 월단위 평균해수면 자료에서는 1 983년의 영산강 하굿둑 건설 사업에 의한 기준고도 변화를 21.2 ㎝ 정도로 추정하였다. 한편 본 연구에서 구성한 모형은 모형의 편향을 유발하는 이상자료의 영향을 포함하며, 모형에 의한 RMS 오차는 연간 자료를 사용한 경우, 부산은 M SL 1 .95 ㎝, 고극조위, 저극조위 각각 5.11 ㎝, 6.50 ㎝이며, 목포의 경우에는 큰 조차의 영향으로 MSL 2.01 ㎝, 고극조위, 저극조위 각각 1 1 .80 ㎝, 9 .1 4 ㎝로 부산보다 다소 높게 나타났다. Modeling for outliers in time series was carried out using the MSL and extreme high, low tide levels (EHL, HLL) data set in the Busan and Mokpo stations. The time-series model is seasonal ARIMA model including the components of the AO (additive outliers) and LS (level shift). The optimal model was selected based on the AIC value and the model parameters were estimated using the ‘tso’ function (in ‘tsoutliers’ package of R). The main results by the model application, i.e.. outliers and level shift detections, are as follows. (1) The two AO are detected in the Busan monthly EHL data and the AO magnitudes were estimated to 65.5 ㎝ (by typhoon MAEMI) and 29.5 ㎝ (by typhoon SANBA), respectively. (2) The one level shift in 1983 is detected in Mokpo monthly MSL data, and the LS magnitude was estimated to 21.2 ㎝ by the Youngsan River tidal estuary barrier construction. On the other hand, the RMS errors are computed about 1.95 ㎝ (MSL), 5.11 ㎝ (EHL), and 6.50 ㎝ (ELL) in Busan station, and about 2.10 ㎝ (MSL), 11.80 ㎝ (EHL), and 9.14 ㎝ (ELL) in Mokpo station, respectively.

기류를 이용한 실온변동 알고리즘이 인체에 미치는 생리적ㆍ심리적 영향에 관한 연구

이주연(Lee Ju-Youn),최호선(Choi Ho-Seon),이기섭(Lee Gi-Seop),허덕(Huh Deok),조관식(Cho Kwan-Shik) 한국생활환경학회 2001 한국생활환경학회지 Vol.8 No.3

The purpose of this study is to clarify the effects of physiological and psychological aspect for the new control algorithm adapted to thermal sensibility. The experiment is conducted in summer. The subjects (4 young females and males) are exposed to the following conditions: combinations of air temperatures (one constant 24℃ and the other temperature ascending from 24℃ to 27℃) in moderate air flow and RH50%. The subjects are exposed to set conditions while sitting on a chair in front of air-conditioner. The following results are obtained; It was rated strong and cold for the images of the air velocity under general air conditioning. In comparison with comfort-power saving air conditioning was rated mild, clear, natural, comfort and preferred. Mean skin temperature was leveled the comfort range of 33±0.5℃ with mentioned comfort algorithm. The comfort algorithm was leveled high 1.5 < slightly comfort ~ comfort > at the thermal comfort vote. PMV (Predicted Mean Vote) was rated -0.5 < PMV < +0.5, and PPD (Predicted Percentage of Dissatisfied) rated PPD < 10% with the comfort algorithm.

무리수(無理數) e의 교수 례(敎授 例)

이병수,양규환,이기섭,Lee, Byeong-Su,Yang, Gyu-Hwan,Lee, Gi-Seop 한국수학교육학회 1997 수학교육논문집 Vol.5 No.-

PIV 유동 계측을 통한 천장형 실내기의 최적 제어 설계

성재용,안광협,이기섭,최호선,이인섭,Sung, Jae-Yong,An, Kwang-Hyup,Lee, Gi-Seop,Choi, Ho-Seon,Lee, In-Seop 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.8

A heating flow discharged from a 4-way ceiling type indoor unit has been investigated to determine the design parameters for the optimal flow control. The flow was measured by a PIV(particle image velocimetry) system and an experimental model of 1/10 scale with a transparent room was devised by satisfying the Archimedes number. This similarity is generally used in cases where the forced convection has similar magnitude of the natural convection. To optimize the heating flow, several vane angles and vane control algorithms of cross and right angle controls were considered. Regarding the vane angle, experimental results show that 30$^{\circ}$is an optimal angle to avoid re-suction flows without significant increase in flow noise. Temperature distribution measured in the environmental chamber ensures the increased thermal comfort when compared to the case, 60$^{\circ}$angle. At the optimal angle, applying open/close control gives rise to more uniform distribution of the heating flow than without control. Especially, the cross-control seems to be satisfactory for thermal comfort.

에어컨과 환기시스템을 적용한 실내 온열 및 환기특성

김경환(Kyung-Hwan Kim),이기섭(Gi-Seop Lee),최호선(Ho-Seon Choi),강태욱(Tae-Wook Kang),정백영(Baik-Young Chung),이감규(Gam-Gue Lee) 대한설비공학회 2003 대한설비공학회 학술발표대회논문집 Vol.2003 No.-

기상청 지진 자료를 이용한 내진설계 지진규모의 신뢰구간 추정

조홍연(Hong Yeon Cho),이기섭(Gi-Seop Lee) 한국해안해양공학회 2017 한국해안해양공학회 논문집 Vol.29 No.1

최근 발생한 기록적인 5.8 규모의 경주지진으로 한반도에서 발생 가능한 지진규모에 대한 관심과 해안구조물에 대한 내진 설계검토에 대한 요구가 고조되고 있다. 본 연구에서는 기상청에서 제공하는 지진규모 자료(규모 3.5, 4.0 이상의 자료)를 이용하여 비모수적인 극치해석 기법을 이용하여 재현기간에 따른 지진규모와 신뢰구간을 추정하였다. 지진규모 4.0 이상의 자료를 이용하여 추정한 결과, 재현기간 50, 100년에 해당하는 지진규모는 각각 5.81, 5.94, 추정 지진규모의 90% 신뢰구간은 각각 5.52-6.11, 5.62-6.29 범위로 추정되었다. 본 연구에서 추정한 지진규모는 공간적인 지진위험 영향을 반영하지 못하는 한계가 있으나, 한반도에서 발생 가능한 지진규모를 극치해석과 가용한 자료의 한정된 기간을 반영하여 신뢰구간을 추정하였기 때문에 다양한 연안 구조물의 설계 관점에서 활용이 가능하다. The interest on the potential earthquake magnitude and the request on the earthquake-resistant design examination for coastal structures are emerged because of the recently occurred magnitude 5.8 earthquake in Gyeoung-Ju, Korea. In this study, the magnitude and its confidence intervals with the return periods are estimated using the KMA earthquake magnitude data (over 3.5 and 4.0 in magnitude) by the non-parametric extreme value analysis. In case of using the “over 4.0” data set, the estimated magnitudes on the 50- and 100-years return periods are 5.81 and 5.94, respectively. Their 90% confidence intervals are estimated to be 5.52-6.11, 5.62-6.29, respectively. Even though the estimated magnitudes have limitations not considering the spatial distribution, it can be used to check the stability of the diverse coastal structures in the perspective of the life design because the potential magnitude and its confidence intervals in Korea are estimated based on the available 38-years data by the extreme value analysis.

해양모니터링 자료의 장기결측 보충 기법

조홍연(Hong-Yeon Cho),이기섭(Gi-Seop Lee),이욱재(Uk-Jae Lee) 한국해안해양공학회 2021 한국해안해양공학회 논문집 Vol.33 No.6

해양모니터링 자료에서 빈번하게 발생하는 장기결측구간의 자료 보충기법을 제안한다. 제안하는 방법은 결측구간의 장기변동 추세 성분과 단기변동 잔차성분을 추정하여 조합하는 방식으로 결측구간의 미지 정보를 추정한다. 이 방법을 이용하여 울릉도 해상부이 자료의 수온 항목, 약 1개월 정도의 장기결측 구간의 자료를 보충하였으며, 부이에서 관측하는 자료 항목에 대해서도 결측 보충을 수행하였다. 보충된 자료는 항목에 따라 차이를 보이지만 변동양상이 적절하게 재현되는 것으로 파악되었다. 이 방법은 추세추정과 잔차 반영에 따른 편향오차와 분산오차가 발생하지만, 장기결측으로 인한 통계적인 측도 추정의 편향오차는 크게 절감하는 것으로 파악되었다. 결측보충 모형의 추정 RMS 오차의 평균과 90% 신뢰구간은 각각 0.93, 0.35~1.95 범위이다. Technique for the long-gap filling that occur frequently in ocean monitoring data is developed. The method estimates the unknown values of the long-gap by the summation of the estimated trend and selected residual components of the given missing intervals. The method was used to impute the data of the long-term missing interval of about 1 month, such as temperature and water temperature of the Ulleungdo ocean buoy data. The imputed data showed differences depending on the monitoring parameters, but it was found that the variation pattern was appropriately reproduced. Although this method causes bias and variance errors due to trend and residual components estimation, it was found that the bias error of statistical measure estimation due to long-term missing is greatly reduced. The mean, and the 90% confidence intervals of the gap-filling model’s RMS errors are 0.93 and 0.35~1.95, respectively.

바람과 파랑 관측 자료의 통계정보 분석

조홍연(Hong-Yeon Cho),이기섭(Gi-Seop Lee) 한국연안방재학회 2016 한국연안방재학회지 Vol.3 No.1

The analysis of the circular data having direction components like wind and wave data should be done using the directional statistics method because the characteristics of direction data are far different from the characteristics of linear data. Diverse statistical methods on the direction data have been suggested. The application of the methods, however, is limited because of the usability and accessibility. In this study, a variety of direction data-based statistical analysis of the wind and wave data sets are carried out to test the performance of the methods. The data used in this study is the wind and wave data of the Pohang buoy operated by the KMA and the analysis are carried by using the R packages. The analysis are focused on the estimation of the basic statistics and correlation coefficients between the data and the optimal smoothing of the data to identify the global variation patterns. The estimation results show that the basic statistics and correlations using linear and circular data sets computed with ease using the R functions supported by the R directional (or circular) data statistics packages. In addition, the optimal smoothing methods can be regarded as the suitable and reasonable methods to identify the typical variation patterns with optimum concept.

에어컨 토출 유동 가시화

안광협(Kwang-Hyup An),이인섭(In seop Lee),최호선(Ho seon Choi),이기섭(Gi seop Lee),허덕(Deok Huh) 대한설비공학회 2000 대한설비공학회 학술발표대회논문집 Vol.2000 No.-

천장형 실내기의 열유동 가시화 및 토출 각도 최적화

성재용(Jaeyong Sung),안광협(Kwang Hyup An),이기섭(Gi Seop Lee),최호선(Ho Seon Choi),이인섭(In-Seop Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5

Fluid flows discharged from a 4-way ceiling type indoor unit has been visualized for various vane angles<br/> using a PIV(particle image velocimetry) system. Then, optimal vane angle has been suggested for the best<br/> thermal comport. For the PIV measurements, a 1/10 scale experimental model with a transparent room was<br/> devised by satisfying the Archimedes number. The results of flow visualizations show that the vane angle<br/> should be less than 30° to avoid re-suction flows and to prevent the main stream being concentrated near the<br/> occupant’s head. However, at the smaller angles, flow induced noise increases. Thus, the vane angle of 30°<br/> has been suggested as an optimum. Temperature distribution measured in the environmental chamber also<br/> indicates that it is profitable for the warm flow near one’s feet.