To mitigate carbon emissions, the government aims to transition to renewable energy sources including hydrothermal energy, specifically through wastewater heat recovery. This process involves extracting heat from wastewater or treated water. However, assessments of demand sources for local cooling and heating have predominantly focused on the proximity of nearby facilities, without conducting comprehensive demand analyses or defining explicit supply areas. This study proposes a methodology for prioritizing suitable wastewater treatment plants (WWTPs) for the implementation and expansion of renewable energy. The methodology is based on the gross floor area of potential wastewater heat demand surrounding WWTPs. Initially, potential supply and demand sources were identified based on the capacity of WWTPs and the gross floor area of buildings capable of utilizing wastewater heat. In the Republic of Korea, 330 WWTPs with a capacity of 5,000 m3/day or more have been recognized as demand sources for wastewater heat recovery. The provision of treated wastewater to structures located within a 500 m radius of the WWTPs for heat recovery is considered a feasible option. The potential wastewater heat demand and renewable energy cluster were identified among the surrounding buildings and complexes A total of 13 potential supplies were identified, provided that the gross floor exceeded 60,000 m². Finally, after prioritizing based on WWTPs with these conditions, the underground plant located in the downtown area was ranked as the highest priority. If further analysis of economic feasibility, CO2 reduction, and energy efficiency are conducted, this approach can be expanded and applied within the framework the Water-Energy Nexus. Wastewater heat can be utilized not only as a renewable energy source but also as a means to enhance wastewater reuse through the supply of treated wastewater.

이동 물체의 전역 경로 탐색에 있어 출발지점과 도착지점은 반드시 필요한 조건 중 하나이다. 선박의 경로 탐색에 있어 도착 가능 지점은 부두 이외 선박의 입출항 전 대기 장소 및 선박 수리 등 다양한 목적으로 이용되는 정박지(Anchorage)도 포함될 수 있다. 이 러한 정박지는 연안 해역 환경에 따라 특정 형태로 설계된 공간으로 경로 탐색을 위한 도착지점은 선박이 정박을 위한 투묘 지점이라고 볼 수 있다. 이에, 본 연구에서는 샘플링 기반 탐색 알고리즘 중 PRM 및 계산 기하학 알고리즘을 통해 정박지라는 특정 공간에 대해 다른 선박이 점유하지 않는 공간 탐색을 통한 투묘 지점 산출 방법을 제시하였다. 또한, 개발된 알고리즘을 검증하기 위하여 국내 목포항 11번 정박지를 대상 해역으로 선정하고 시뮬레이션을 수행한 결과 다른 선박이 점유하지 않는 공간에 대해 투묘 지점을 탐색할 수 있었다. 본 연구의 결과는 향후 선박의 의사 결정 및 VTS의 정박지 관리를 위한 지원 방안으로 활용될 수 있을 것으로 기대된다.

In this study, various pre-treatment methods were evaluated for microalgae separation. These methods aimed to facilitate safe, rapid, and cost-effective online imaging for real-time observation and cell counting. As pre-treatment techniques, heating, chemical hydrolysis, heating combined with chemical hydrolysis, and sonication were employed. The effectiveness of these methods was evaluated in the context of online imaging quality through experimentation on cultivated microalgae (Chlorella vulgaris and Scenedesmus quadricauda). The chemical treatment method was found to be inappropriate for improving image acquisition. The heating pre-treatment method exhibited a drawback of prolonged cell dispersion time. Additionally, the heating combined with chemical hydrolysis method was confirmed to have the lowest dispersion effect for Chlorella vulgaris. Conversely, ultrasonication emerged as a promising technique for microalgae separation in terms of repeatability and reproducibility. This study suggests the potential for selecting optimal pre-treatment methods to effectively operate real-time online monitoring devices, paving the way for future research and applications in microalgae cultivation and imaging.

전 세계적으로 급격하게 성장하는 스마트농업의 중요 요소 중 하나인 자동 관개시스템은 토양수분 센서에서 계측한 데이터를 기반으로 관개시점과 관개량을 판단하기 때문에 토양수분 센서의 설치가 필수적이다. 하지만 국내의 경우 토양을 고려하지 않고 단순히 포장의 가운데에 센서를 설치하는 등 토양수분 센서의 설치 위치에 대한 기준이 마련되어 있지 않아 토양수분 계측 위치에 관한 기준 검토가 필요하다. 본 연구에서 통계학적 방법을 이용하여 토양수분의 대표 계측지점을 선정 연구를 수행하였다. 토양은 수직적 또는 수평적으로 불균일성을 갖기에 구명이 쉽지 않다. 따라서 포장 전체에 걸쳐 지속해서 편향이 발생하지만 특정 위치에서의 평균 토양수분이 시간에 따라 유지한다는 시간 안정성 개념을 기반으로, 평균 토양수분을 나타내는 대표지점 선정 연구를 수행하였다. 토양수분을 측정하기 위한 시스템을 제작하였고, TDR (Time Domain Reflectometry) 센서를 이용하여 총 30개 지점을 측정하였다. 2023년 5월부터 8월까지 측정한 날짜·지점별 데이터를 이용하여, 지점의 편향을 정량화하여 식별할 수 있는 MRD (Mean Relative Difference, 평균상대차이)와 측정의 정밀도를 나타내는 RD (Relative Difference, 상대차이)의 SDRD (Standard Deviation of Relative Difference, 표준편차)를 산출하고, MRD와 SDRD를 통합한 지표로써 RMSE (Root Mean Square Error, 평균제곱근오차) 를 구하여, 시간 안정성이 가장 높은 지점인 RMSE의 수치가 최소인 지점을 대표지점으로 선정하였다. 토양수분 센서로 측정한 데이터를 사용하여 지점별 RMSE를 산출하고 비교하여, 평균적인 토양수분을 나타내는 대표지점을 선정할 수 있음을 확인하였다.

탁주의 제조과정 중 사입량의 비율을 조절하여 담금 조건을 달리하는 증량 담금법과 3단 담금법으로 탁주를 제조하여 탁주의 품질특성을 조사하였 다. 3단 담금법에서 초기 당도가 높았으나, 발효가 진행됨에 따라 발효 6일차 까지는 10.5oBrix로 서서히 감소하다가, 그 이후 다시 상승하였다. 증량 담금법의 알코올 증가량은 3단 담금법에 비해 초기 발효속도는 완만했으나 발효완료 시 16.0%에 도달한 반면, 3단 담금법은 초기 발효속도가 빨랐으나, 14.9%로 발효가 완료되었다. 초기 아미노산도는 3단 담금법에서는 2.3%로 높았으나, 증량 담금법은 아미노산도가 서서히 증가하여 발효완료시 3.2%였고, 3단 담금법에서는 3.3%에 도달하였다. 증량 담금법에서 Sake meter value (SMV)는 발효 3일차에 -13.1까지 감소하였으나, 그 이후 지속적으로 증가하여 발효 종료시 11.3으로 나타났다. 관능검사 결과 전반적 기호도는 단맛과 쓴맛의 기호도가 우수했던 증량 담금법에서 더 높게 나타났다.

K-means algorithm is one of the most popular and widely used clustering method because it is easy to implement and very efficient. However, this method has the limitation to be used with fixed number of clusters because of only considering the intra-cluster distance to evaluate the data clustering solutions. Silhouette is useful and stable valid index to decide the data clustering solution with number of clusters to consider the intra and inter cluster distance for unsupervised data. However, this valid index has high computational burden because of considering quality measure for each data object. The objective of this paper is to propose the fast and simple speed-up method to overcome this limitation to use silhouette for the effective large-scale data clustering. In the first step, the proposed method calculates and saves the distance for each data once. In the second step, this distance matrix is used to calculate the relative distance rate (Vｊ) of each data j and this rate is used to choose the suitable number of clusters without much computation time. In the third step, the proposed efficient heuristic algorithm (Group search optimization, GSO, in this paper) can search the global optimum with saving computational capacity with good initial solutions using Vｊ probabilistically for the data clustering. The performance of our proposed method is validated to save significantly computation time against the original silhouette only using Ruspini, Iris, Wine and Breast cancer in UCI machine learning repository datasets by experiment and analysis. Especially, the performance of our proposed method is much better than previous method for the larger size of data.

Logistic enterprises want to be competitive enterprises in fierce logistic market and worry about the securement of discriminative competitiveness for it. The standards for the judgement of logistic industry’s maintenance of competitiveness are not only economic feasibility of logistic costs but also the satisfaction of users because well-established service system for variety and enhancement of logistic needs. Some of the quality attributes sufficiently satisfy expectation of customers, but not guarantee high-quality satisfaction. Therefore, it’s difficult to grasp quality attributes with the existing approach of perceived service quality. Quality attribute model suggested by Kano is widely used as the concept is accurate, there is high possibility to be used at the stage of product/service planning, and it can be easily applied. Kano model has a limitation that quality attributes are classified with mode and the differences between strong property of the quality attribute and week property in quality attributes were ignored. Therefore, Timko calculated customer satisfaction coefficient with the result of Kano’s survey and effects of customer satisfaction and unsatisfaction through relations between satisfaction coefficient and unsatisfaction coefficient. The purposes of this study are to use ASC, the average of satisfaction coefficient and unsatisfaction, as the satisfaction of quality characteristics, decide the importance of quality characteristics with TOPSIS, a representative multi-standard decision-making method, and calculate strategy improvement propriety of logistic service quality.

For estimating the seismic demand of buildings, most seismic design provisions permit conducting linear and nonlinear response history analysis. In order to obtain reliable results from response history analyses, a proper selection of input ground motions is required. In this study, an accurate algorithm for selecting and scaling ground motions is proposed, which satisfies the ASCE 7-10 criteria. In the proposed algorithm, a desired number of ground motions are sequentially scaled and selected from a ground motion library without iterations.

Classify of explosion hazardous areas must be made at the site where flammable materials are used. This reason is that it is necessary to manage ignition sources in of explosion hazardous areas in order to reduce the risk of explosion. If such an explosion hazard area is widened, it becomes difficult to increase the number of ignition sources to be managed. The method using the virtual volume currently used is much wider than the result using CFD(Computational Fluid Dynamics). Therefore, we tried to improve the current method to compare with the new method using leakage characteristics. The result is a realistic explosion hazard if the light gas is calibrated to the mass and the heavy gas is calibrated to the lower explosion limit. However, it is considered that the safety factors should be taken into account in the calculated correction formula because such a problem should be considered as a buffer for safety.

There is a growing concern on the improvement of water distribution pipeline for multi-regional water supply system in Korea along with its aging infrastructure. Rehabilitation of large diameter pipeline is more efficient in cost and time compared to replacement with trenching. The procedure for rehabilitation are diagnosis, cleaning, spraying coating material, and final inspection. The internal state of pipeline was carefully diagnosed and got C grade, which required rehabilitation. We found that 17,274,787,000 Korean won could be saved after pipe surface coating because of increased C coefficient of Hazen-Williams equation. Optimal coating material was D polyurea. We also found optimal distance between spraying nozzle and pipe wall to be 70 - 80 cm, which were critical factors for coating quality. This study also illustrated the time for spray drying to be more than 30 min. These results could be used in the quality control process during rehabilitation of aged pipelines.

This research determined priority of quality improvement of public institution's education service by using ASC for importance and applying Topsis, a multi-standard decision-making method simplifying various attributes and scales of evaluation items and deciding the comparative priority for satisfaction and discussed the differences so as to measure the quality of public institution's educational service and examine the priority of education service' quality improvement. This research classified the characteristics of quality improvement. As a result, it's significant to suggest positive direction and method to improve satisfaction and education service's quality from an angle of demander by analyzing educational satisfaction of education service quality of public education institution and effects on the following improvement.

It is important to select proper ground motions for obtaining accurate results from response history analyses. The purpose of this study is to propose an accurate and efficient method that does not require excessive computation for selecting and scaling ground motions to match target response spectrum mean and variance. The proposed method is conceptually simple and straightforward, and it does not use a simulation algorithm that requires a sophisticated subroutine program. In this method, the desired number of ground motions are sequentially scaled and selected from a ground motion library. The proposed method gives the best selection results using Sum of Square Error and has the smallest value(=0.14). Also, The accuracy and consistency of the proposed method are verified by comparing the selection results of the proposed method with those of existing methods.

This study is the sequel of a companion paper (I. Algorithm) for assessment of the seismic performance evaluation of structure using ground motions selected by the proposed algorithm. To evaluate the effect of the correlation structures of selected ground motions on the seismic responses of a structure, three sets of ground motions are selected with and without consideration of the correlation structure. Nonlinear response history analyses of a 20-story reinforced concrete frame are conducted using the three sets of ground motions. This study shows that the seismic responses of the frames vary according to ground motion selection and correlation structures.

It is important to select an accurate set of ground motions when conducting linear and nonlinear response history analyses of structures. This study proposes a method for selecting ground motions from a ground motion library with response spectra that match the target response spectrum mean, variance and correlation structures. This study also has addressed the determination of an appropriate value for the weight factor of a correlation structure. The proposed method is conceptually simple and straightforward, and does not involve a simulation algorithm. In this method, a desired number of ground motions are sequentially selected from first to last. The proposed method can be also used for selecting ground motions with response spectra that match the conditional spectrum. The accuracy and efficiency of the proposed procedure are verified with numerical examples.

In this study, determination methods of monitoring location in water distribution system were suggested and applied to real test bed. Small block of Gwangtan water distribution system is consisted of 582 pipes, 564 junctions, 1 reservoir, and 1 pump station. Small block of Ho Chi Minh water distribution system is consisted of 162 pipes, 148 junctions, and 1 reservoir. Two small block water distribution systems were analyzed by pressure contribution analysis method to determine the optimum monitoring locations. The pressure change was estimated at each junctions by the additional demand at a junction. From the results, the optimum monitoring location can be determined by rank of pressure contribution index at each junctions due to demand change at a junction.

This study intends to propose a non-oriented DEA based game cross-efficiency approach for supplier selection. With a discussion on the choice of DEA models and approaches that are most appropriate for supplier selection, we propose a game cross efficiency model based upon the non-oriented variable returns-to-scale RAM DEA by adapting the existing game cross efficiency model based upon the oriented constant returns-to-scale CCR DEA. We develop the RAM game cross efficiency model and a convergent iterative solution procedure to find the best game cross efficiency scores that constitute a Nash equilibrium. We illustrate the proposed model with two data sets of supplier selection, and demonstrate that significantly different results are obtained when compared with the existing approaches.