• 한국해양공학회지
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• 제31권6호
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• pp.379-387
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• 2017

In this study, a pile-guide mooring system (PGMS) was designed for an offshore liquefied natural gas bunkering terminal (LNG-BT), which is an essential infrastructure for large LNG-fuelled ships. The PGMS consisted of guide piles to restrict five motions of the floater, except for heave, as well as a seabed truss structure to support the guide piles and foundation piles to fix the system to the seabed. Singapore port was considered for a case study because it is a highly probable ports for LNG bunkering projects. The wave height, current speed, and wind speed in Singapore port were investigated to calculate the environmental loads acting on the hull and PGMS. A load and resistance factor approach was used for the structural design, and a finite element analysis was performed for design verification. The steel usage of the PGMS was analyzed and compared with the material usage of a gravity-based structure under similar LNG capacity and water depth criteria. This paper also describes the water depth limit and wave conditions of the PGMS based on estimation of the initial investment and the present value profit difference. It suggests a suitable LNG-BT support system for various design conditions.

• 설비공학논문집
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• 제29권4호
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• pp.185-194
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• 2017

Currently, in comparison with other architectural estimations, the estimation work regarding building mechanical-service systems is time-consuming, and the process is continuously becoming more difficult because of the increased usage of the attached piping materials such as fittings and hangings in addition to their complicated construction processes. To improve this problem, the Korean authority provides a simple estimation method for the attached-material rate regarding the main piping material, which is the most time-consuming work in the architectural-mechanical estimation. However, to be an applicable method on construction sites, a proper conversion rate of the attached-piping material is still required for the proposed method regarding building usage and working types. Therefore, the purpose of this research is the calculation of the rate of the attached-piping materials such as the fittings and supports through the building of the mechanical-service work types of mechanical rooms, air conditioning, domestic water and hot-water supplies, and the drain-, vent-, and gas-piping work in office buildings that have been designed after 2010.

• 한국환경복원기술학회지
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• 제15권5호
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• pp.103-114
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• 2012

The purpose of this research is classifying stream into different types depending on various factor from the perspective of stream corridor restoration and using it as basic data, which are used to consider efficient management and planning for the healthy stream according to the characteristic by types. In this study, 130 points of location of the Nakdong river basin which consist of various geographic factors have been chosen and hierarchical cluster analysis has been carried out in these points by using biological and physiochemical factors whose health can be considered to be predicted and evaluated. As a result of cluster analysis, there were three divided types. Type A whose biology and water quality are considered the best was the highest in forest area percentage so that it was classified into natural stream. Type B was classified into a rural region stream with a mixture of urban and agricultural region. Type C, with the most damaged water quality and biology health had the most urban region surface area and was named as urban region stream. Moreover, an overall restoration strategy according to characteristic by stream types was set. By the results of correlation analysis on factors, water quality showed a high correlation with biological properties and was affected by surrounding land usage. In evaluation of streams, it proves the need to consider not only other habitat's geographical and biological factors but also the water quality and land usage factors. There needs to be further research on stream ecosystem functionality factors and structural aspects by using a more objective and total evaluation result in selecting additional index and various other specific classification methods by stream types and its restoration strategies.

• 한국전자통신학회논문지
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• 제14권3호
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• pp.537-546
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• 2019

본 논문에서는 스마트 전력량계에 세대집중화장치를 내장하여 AMI에 필요한 가스, 수도, 온수, 난방 검침을 일괄검침하는 시스템과, 검침데이터를 에너지정보표시장치(IHD: In House Display)와 서버로 전송하는 방법을 구성하여 보다 경제적으로 AMI 시스템을 구축하는 방법을 제시한다. 개발된 시스템은 기존 시스템 보다 네트워크 구성에 있어서 가격이 저렴하고 운영비용이 절감되며 설치가 용이하다. 개발된 시스템을 적용하면 전기, 수도, 가스, 온수 및 난방의 5종 계량기의 계량값을 원격검침 하고 이에 대한 AMI 적용을 보다 용이하게 구성 가능하다. 주요개발 내용은 스마트 전력량계 구성과 세대집중화장치 결합 및 이들 데이터를 IHD와 서버로 전송하는 방법이며, 이들 요소들을 연계하여 시스템을 구성하고 실제 검침 동작구성을 테스트하고 그 결과를 보여준다.

• 한국물환경학회지
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• 제36권6호
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.45-54
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• 2007

For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply Based on fluid dynamic and heat transfer theories, a series of modeling and simulation is conducted to achieve practical design requirements. An experimental setup is built and tested and the results are compared with theoretical simulation model. The storage tank capacity is 240 l and the outer diameter of piping was 15 mm. Number of tube turns tested are 5, 10, and 15. Starting with initial storage tank temperature of $80^{\circ}C$, the temperature variation of the supply hot water is investigated against time, while maintaining minimum flow rate of 10 1/min. Typical results show that the hot water supply of minimum $30^{\circ}C$ can be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincide well within 10% in most cases.

• 대한안전경영과학회지
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• 제17권1호
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• pp.149-168
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• 2015

It is expected that the temperature in Pyeongyang will be similar to that ($16.6^{\circ}C$) in Seogwipo in the late 21st century, and most of South Korea will enter the subtropical climate due to climate change. Change in the precipitation pattern like the range of fluctuation caused by climate change will lead to expanded uncertainty in securing reliable water supply, along with a serious impact on demands for living and industrial water due to change in the volume and period of river outflow. As industrial water for production activities is estimated based on the contract quantity, it is difficult to apply rationalization of water usage and incentives in water recycling. Therefore many companies are making efforts in complying with the effluent standard while spending few resources on such rationalization and recycling. This study researched water risk management over 115 Korean companies by 28 questions in 4 categories. Through the research, this study aims to understand water risk management levels and seek response plans.

• 대한건축학회논문집:구조계
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• 제34권9호
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• pp.27-34
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• 2018

The purpose of this study is to demonstrate and analyze the function of a Smart Plug before and after it is applied on the electrical appliances by controlling standby power usage. The research measures and analyzes the amount of electrical energy used while activating the Smart Plug with two types of appliances in a university facilities. The smart plugs were applied into a Group 1 appliances (Multi-function device, computer, laptop, Air con) which completely hinder the standby power, and a Group 2 appliances (Refrigerator, cold and hot water dispenser) which does not completely hinder the standby powers due to the characteristics of the function. First, the total standby power saving of all electrical appliances (Group 1 and Group 2) using the Smart plug was measured as 4.59%. Second, the energy saving of the Group 1 products was analyzed as 26.43%. Third, the standby power saving of the air conditioners from mid October to early December was measured as 31.06%, during the seasons when air conditioning was not actively in use. The research indicates that all specified appliances did have better energy efficiency with the Smart plug regardless of the amount of energy usage.

• 한국환경과학회지
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• 제24권1호
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• pp.65-71
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• 2015

This study accessed the adsorption characteristics of the 9 trihalomethanes (THMs) on coal-based granular activated carbon (GAC). The breakthrough appeared first for $CHCl_3$ and sequentially for $CHBr_2Cl$, $CHBr_3$, $CHCl_2I$, CHBrClI, $CHBr_2I$, $CHClI_2$, $CHBrI_2$, and $CHI_3$. The maximum adsorption capacity (X/M) for the 9 THMs with apparent breakthrough points ranged from $1,175{\mu}g/g$ (for $CHCl_3$) to $11,087{\mu}g/g$ (for $CHI_3$). Carbon usage rate (CUR) for $CHCl_3$ was 0.149 g/day, 5.5 times higher than for $CHCl_3$ (0.027 g/day).

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.2122-2126
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• 2008

With the degradation of water quality and, at the same time increased water usage, the sources of high quality, for examples, river/stream, municipal reservoir, wells, artisan and surface water, are diminishing. Therefore, the importance of water quality has been emphasized over the years through publications and various literature sources. Even though considerable research has resulted in significant strides for providing interpretive information and mitigation strategies for improvement of waters, the quality of which is still questionable. This study aims to propose a completely independent self-contained system for purifying waters, solar-powered ozone generator. It is a semi-permanent and cost effective environmental solution. Functions of ozone treatment are: 1) to maintain oxidative flexibility, 2) remove harmful chemicals, wastes, and other substances, and 3) prevent epizootic microbial outbreaks. Recent advances in technology have allowed the development of the practical, self-contained and independent solar powered device. Solar electrical producing panels that charge batteries are the key to using these systems anywhere electrical power is not available. This paper invites the readers to examine the problem and consider the viable, proven solution the solar powered ozone purifying system. This paper also introduces basic concept and background of solar powered ozone generators and examine its feasibility for improving water quality in rivers and streams.