최근 대학교육에서 핵심역량 증진을 위한 교수설계를 강조하고 있다. K대 교양중 국어수업에서 핵심역량은 의사소통 영역, 문제해결 영역, 공감 영역이다. 수업 설계 에서 의사소통은 언어표현, 문제해결 능력은 중국 여행 지식, 공감 영역은 중국문화 지식과 연계시켜 구성하였으며 이에 대한 설문조사를 진행하였다. 설문 결과, 학습자 들은 언어표현은 가급적 적게 배우길 희망하였다. 공감 영역의 중국문화 부분에서 중국문화 영역에 대한 관심도 많았지만, 외국인으로서 중국에 갔을 때 주의해야 할 예절에도 많은 관심을 보였다. 본 수업을 통해서 의사소통 영역에서 55%, 문제해결 영역에서 54%, 공감 영역에서 65%의 학습자들이 해당 영역의 핵심역량이 향상되었 다고 답하였다. 특히 의사소통, 문제해결 영역보다 공감 영역이 상대적으로 증가되었 다는 것을 알 수 있는데, 이는 학습자들이 언어표현, 중국 여행보다는 중국문화에 더 많은 관심이 있다는 반증이라고 할 수 있다.

The water consumption data of individual consumers must be analyzed and forecast to establish an effective water demand management plan. A k-mean cluster model that can monitor water use characteristics based on hourly water consumption data measured using automated meter reading devices and demographic factors is developed in this study. In addition, the quantification model that can estimate the daily water consumption is developed. K-mean cluster analysis based on the four clusters shows that the average silhouette coefficient is 0.63, also the silhouette coefficients of each cluster exceed 0.60, thereby verifying the high reliability of the cluster analysis. Furthermore, the clusters are clearly classified based on water usage and water usage patterns. The correlation coefficients of four quantification models for estimating water consumption exceed 0.74, confirming that the models can accurately simulate the investigated demographic data. The statistical significance of the models is considered reasonable, hence, they are applicable to the actual field. Because the use of automated smart water meters has become increasingly popular in recent year, water consumption has been metered remotely in many areas. The proposed methodology and the results obtained in this study are expected to facilitate improvements in the usability of smart water meters in the future.

이 논문은 울릉도, 독도를 포함하는 동해 울릉분지 해저 화산그룹(가칭: 울릉도-독도 화산그룹)의 분화사를 복원 하고 미래 분화 가능성을 평가하기 위해 진행중인 육상-해양 복합 다중스케일 화산연구의 개념과 지금까지의 결과를 소개하는데 목적을 둔다. 다중채널 탄성파반사자료 해석을 통해 유추되는 울릉도-독도 화산그룹의 주 활동 시기는 대략 5-2.5 Ma로, 동쪽 끝의 이사부평정해산에서 처음 시작되어 서쪽의 울릉도로 전파된 것으로 해석된다. 울릉도의 육상부 는 5단계에 걸쳐 생성되었으며 최종 단계에 접어들어 폭발성 분화를 통해 폭 약 3 km의 칼데라 지형과 그 내부에 화 산돔을 형성하였다. 울릉도의 마지막 분화 산물인 알봉 화산돔과 그 하부의 수증기마그마성 분화로부터 기원된 층단위 N-1 화산쇄설층은 기존 포놀라이트질 마그마방으로 유입된 보다 염기성의 새로운 마그마의 분화로부터 생성되었다. 층 단위 N-1과 알봉 분석이 갖는 조면안산암질 전암조성은 기존 포놀라이트질 마그마방 하부에 존재한 고철질 집적암이 새로 주입된 마그마를 오염시킨 결과로, 그 자체가 마그마의 조성을 지시하지는 않는다. 층단위 N-1과 알봉 화산돔에서 확인되는 새로운 마그마 주입의 증거들은 최근 밝혀진 울릉도의 높은 지온구배 및 분화주기와 더불어 울릉도가 여전히 작동중인 마그마 배관체계를 갖는 활화산임을 암시한다.

Conventionally, metal materials are produced by subtractive manufacturing followed by melting. However, there has been an increasing interest in additive manufacturing, especially metal 3D printing technology, which is relatively inexpensive because of the absence of complicated processing steps. In this study, we focus on the effect of varying powder size on the synthesis quality, and suggest optimum process conditions for the preparation of AlCrFeNi high-entropy alloy powder. The SEM image of the as-fabricated specimens show countless, fine, as-synthesized powders. Furthermore, we have examined the phase and microstructure before and after 3D printing, and found that there are no noticeable changes in the phase or microstructure. However, it was determined that the larger the powder size, the better the Vickers hardness of the material. This study sheds light on the optimization of process conditions in the metal 3D printing field.

본 연구는 新HSK문법 등급에 제시된 문법 등급이 실제 기출문제에 어떻게 반영 되는지 알아보고, 그 대응방안을 찾는데 목적이 있다. 이를 위해서 新HSK 출제기관 인‘汉办’에서 2015년 제시한 등급을 찾고, 2020년에 발행된 실제 기출문제 제1회차부 터 제5회차에서 해당 문법 등급을 찾은 후에, 서로 교차 대조하였다.본 연구 결과 2 급에서는 결과보어, 가능보어, 명량보어, 비교문, 겸어문, 전치사 등의 문법 등급에서 범위를 초과하였다. 3급에서는 결과보어, 방향보어, 가능보어, 명량보어, 비교문, 전치 사 등의 문법 등급에서 범위를 초과하였다. 이는 2급과 3급 문법 등급과 실제 기출 문제 사이에 일정한 편차가 있다는 것을 증명하는 것으로써, 新HSK 시험 지도에 많은 도움을 줄 수 있다. 향후, 등급별로 대조하는 것을 제안한다.

This paper is to study the technology of inspection and history management systems for wind power that are continuously increasing around the world. In the past, inspections and analysis of major devices in renewable energy system have been operated in an analog way that identifies problems through photography and passive method. To improve this problem, we conduct a study on VR-based inspection history management system using 3D texturing technique of drone image. The paper describes the current status and prospects of wind power, research and development of wind power blade inspection and history management systems, experiments and reviews in the field, and expected effects and future utilization of this technology. It is expected that the latest technology for inspection and management of renewable system will be secured and introduced to the site through the development research of this system to reduce maintenance costs and power generation costs.

The water supply facilities of Korea have achieved a rapid growth, along with the other social infrastructures consisting a city, due to the phenomenon of urbanization according to economic development. Meanwhile, the level of water supply service demanded by consumer is also steadily getting higher in keeping with economic growth. However, as an adverse effect of rapid growth, the quantity of aged water supply pipes are increasing rapidly, Bursts caused by pipe aging brought about an enormous economic loss of about 6,161 billion won as of 2019. These problems are not only worsening water supply management, also increasing the regional gap in water supply services. The purpose of this study is to classify hazard evaluation indicators and to rank the water distribution network hazard by cluster using the TOPSIS method. In conclusion, in this study, the entropy-based multi-criteria decision-making methods was applied to rank the hazard management of the water distribution network, and the hazard management ranking for each cluster according to the water supply conditions of the county-level municipalities was determined according to the evaluation indicators of water outage, water leakage, and pipe aging. As such, the hazard ranking method proposed in this study can consider various factors that can impede the tap water supply service in the water distribution network from a macroscopic point of view, and it can be reflected in evaluating the degree of hazard management of the water distribution network from a preventive point of view. Also, it can be utilized in the implementation of the maintenance plan and water distribution network management project considering the equity of water supply service and the stability of service supply.

This study set up the estimates of leakage management efficiency evaluation and leakage management goal that could be used in local water distribution networks efficiency business and modernization business. The data were analyzed using data envelopment analysis and multiple regression analysis. To this end, with leakage management input indices concerning leakage reduction activities (e.g., aged pipe replacement, water meter replacement, leakage restoration, and leakage detection) and leakage management calculation indices (e.g., the increase of revenue water ratio and the reduction of leakage ratio), the data on 22 K-water consignment local water supply systems were analyzed for the years from 2004 through 2018. Using the results of efficiency analysis by data envelopment analysis, the other DMUs (Decision Making Unit) benchmarked the DMU with the highest efficiency to maximize the leakage management efficiency for all DMUs. Through this, leakage management goal estimates were drawn with the input indices of four leakage reduction activities and calculation indices of the increase of revenue water ratio and the reduction of leakage ratio by multiple regression analysis for each group based on the revenue water ratio and leakage ratio. The correlation coefficients of the leakage management goal estimate for the criteria for the revenue water ratio amounted to 0.553 and 0.771. The correlation coefficients of the leakage management goal estimate for the criteria for leakage ratio were 0.397 and 0.865. Accordingly, we estimated the quantity and priority of four leakage reduction activities for the target leakage ratio and revenue water ratio.

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of 4.9 m3 yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.

This study developed prediction models of chlorine bulk decay coefficient by each condition of water quality, measuring chlorine bulk decay coefficients of the water and water quality by water purification processes. The second-reaction order of chlorine were selected as the optimal reaction order of research area because the decay of chlorine was best represented. Chlorine bulk decay coefficients of the water in conventional processes, advanced processes before rechlorination was respectively 5.9072 (mg/L)-1d-1 and 3.3974 (mg/L)-1d-1, and 1.2522 (mg/L)-1d-1 and 1.1998 (mg/L)-1d-1 after rechlorination. As a result, the reduction of organic material concentration during the retention time has greatly changed the chlorine bulk decay coefficient. All the coefficients of determination were higher than 0.8 in the developed models of the chlorine bulk decay coefficient, considering the drawn chlorine bulk decay coefficient and several parameters of water quality and statistically significant. Thus, it was judged that models that could express the actual values, properly were developed. In the meantime, the chlorine bulk decay coefficient was in proportion to the initial residual chlorine concentration and the concentration of rechlorination; however, it may greatly vary depending on rechlorination. Thus, it is judged that it is necessary to set a plan for the management of residual chlorine concentration after experimentally assessing this change, utilizing the methodology proposed in this study in the actual fields. The prediction models in this study would simulate the reduction of residual chlorine concentration according to the conditions of the operation of water purification plants and the introduction of rechlorination facilities, more reasonably considering water purification process and the time of chlorination. In addition, utilizing the prediction models, the reduction of residual chlorine concentration in the supply areas can be predicted, and it is judged that this can be utilized in setting plans for the management of residual chlorine concentration.

In this study, the leak signal was measured by using an accelerometer to analyze the basic data and methodology for the development of the leak point estimation method in the water supply pipe. The measured results were analyzed by frequency analysis and cross-correlation analysis for leakage signals, and the error range was compared and analyzed with the actual leak point distance. As a result, it was confirmed that the vibration intensity due to leakage from the water leakage point was attenuated according to the distance. In the case of the ductile iron casting used in the experiment, the intensity of the signal at the 945 Hz, 1,500 Hz, 2,300 Hz band was increased with the change of the pressure in the pipe at 4mm of leakage hole. Also, it was confirmed that as the water pressure increases, the intensity of the leak signal increases but the similarity of the signal decreases. The results of this study confirm that the accelerometer sensor can be used efficiently for leak detection and it can be used as a basic data for the analysis for the development of leak point estimation method in the future.

Most of aged water supply pipes have been replaced by the open cut method. However, this method has some limitations because water pipes, in many cases, are buried together with other underground facilities or are buried in the middle of high-traffic roads or in narrow alleyways where boring machines cannot be used. This research developed a pipe bursting device for small diameter pipes that enables pipe replacement without excavating the ground, by the busting of existing buried pipes followed by the traction and insertion of new pipes. As a results of examining the field applicability of the developed device, PE pipes and PVC pipes required the tractive force of 413.65～665.69 kgf and 457.43～791.35 kgf respectively, plus an additional 30 % tractive force per elbow. The proper number of bursting head was demonstrated that the connection of more than 2 heads could secure a stable bending radius of 15D. The developed device can be improved through field experiments involving various pipe types and pipe diameters, as well as presence/absence of elbow, so as to be utilized regardless of diverse variables according to the conditions of the soils surrounding existing pipes.

Water supply/intake pumps operation use 70~80% of power costs in water treatment plants. In the water treatment plant, seasonal and hourly differential electricity rates are applied, so proper pump scheduling can yield power cost savings. Accordingly, the purpose of this study was to develop an optimal water supply pump scheduling scheme. An optimal operation method of water supply pumps by using genetic algorithm was developed. Also, a method to minimize power cost for water supply pump operation based on pump performance derived from the thermodynamic pump efficiency measurement method was proposed. Water level constraints to provide sufficient disinfection performance in a clearwell and reservoirs were calibrated. In addition, continuous operation time constraints were calibrated to prevent frequent pump switching. As a result of optimization, savings ratios during 7 days in winter and summer were 4.5% and 5.1%, respectively. In this study, the method for optimal water pump operation was developed to secure disinfection performance in the clearwell and to save power cost. It is expected that it will be used as a more advanced optimal water pump operation method through further studies such as water demand forecasting and efficiency according to pump combination.

This study develops a model to estimate the economic life of the large-diameter water supply pipeline in Korea by supplementing existing methods used to perform similar calculations. To evaluate the developed methodology, the model was applied to the actual target area with the conveyance pipe in P waterworks. The application yielded an economic life computation of 39.7 years, considering the cost of damages, maintenance, and renewal of the pipeline. Based on a sensitivity analysis of the derived results, the most important factor influencing the economic life expectancy was the predicted failure rate. The methodology for estimating the economic life of the water supply pipeline proposed in this study is one of the core processes of basic waterworks facility management planning. Therefore, the methods and results proposed in this study may be applied to asset management planning for water service providers.