• KCID journal
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• v.21 no.1
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• pp.109-117
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• 2014

Multi water-loop system is the efficient customer centered facilities of water supply by utilizing the multi water resources. Multi water-loop system is divided into various types. The system is classified potable and non-potable type. Mostly, the potable type utilizes surface water and ground water. However, the non-potable type utilize the multi water resources, such as rain water, sea water, reclaimed water, etc. Selective intake is possible when characteristics of region, physiographic condition and purpose of use are considered. For instance, downtown type, new-city type, agriculture type, island type are available. For development and application of these multi water-loop system, standardization is needed. For standardization, several methods are given; design principles, selection and composition method of multi water-loop system structure, BIM/GIS application method, safety inspection method. Consequently, a road map of design standardization method can be established. In this road map, there are three parts for the standardization of multi water-loop system. Three parts are the considerations, base material and ways of standardization. Design standardization become close when this road map followed by someone who plan the multi water-loop system. In this way, loop system's development is more efficient and economic. In hereafter research, each type's characteristic will be analysed and standardization methods can be established.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.15-19
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• 2006

유출지하수나 지표수를 열원으로 하는 지열히트펌프의 Pond Loop형 열교환기를 개발하기 위하여 미국에서 상용화된 Slim-Jim 열교환기와 본 연구에서 자체설계, 제작한 Pond-loop type의 열교환기를 유동이 없는 유출수조 내에서 수조온도가 변화함에 따라 일정한 열교환기 입구온도를 유지하면서 열전달량의 변화를 측정하였다. 그 결과 유출수를 Heat Source로 사용하는 경우 Slim-Jim에서는 $8,000{\sim}11,000 kcal/hr$의 열량이 전달되었고, 자체 제작한 열교환기에서는 $11,000{\sim}16,000kcal/hr$의 열량이 전달되었다. 유출수를 Heat Sink로 사용할 경우 Slim-Jim에서는 $2,500{\sim}7,000 kcal/h$의 열량이 전달되었고, 자체제작한 열교환기의 경우, $6,800{\sim}14,00 kcal/hr$의 열량이 전달되었다. 측정된 열전달량을 바탕으로 총괄열전달계수를 구한 결과 Slim-Jim 열교환기의 경우 $210{\sim}340 kcal/hr\;m^2{\circ}C$, 자체개발한 열교환기의 경우 $350{\sim}590 kcal/hr\;m^2{\circ}C$로 나타나 자체 개발한 열교환기의 열전달 성능이 비교적 우수함을 입증하였다.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.35-42
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• 2018

Among the various ground source heat pump systems, vertical-type heat pump systems have been distributed greatly. Most of the vertical-type ground source heat pump systems have been designed based on the Korean Ministry of Knowledge Economy Announcement in Korea. In this study, the design process of the vertical-type ground source heat pump system in the announcement was analyzed, and the effects of the design parameters on the ground loop heat exchanger were investigated. Borehole thermal conductivity was the highest dominant design parameter for ground loop heat exchangers. The borehole thermal conductivity was changed according to the pipe and grout thermal conductivity. For optimal design of the ground heat pump system, it is highly recommended that the design process in the announcement will be revised to adopt the various tubes and grout which have higher thermal conductivity. In addition, the certification standard for heat pump unit should be revised to develop the heat pump with a small flow rate.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.1
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• pp.14-19
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• 2014

This paper presents a preliminary experimental and computational study on the evaluation of thermal performance and initial cost of U, W and coil type ground heat exchangers (GHEs). Heat exchange rate of the individual GHE was evaluated from the thermal resperformance test (TPT) results, and the construction cost was also calculated. For more information, GLD (ground loop design) simulations of various piping size are carried out. From simulation results, the optimized GHE was suggested based on the thermal performance and construction cost as well. Besides, the required borehole length of U and W type GHEs was calculated considering a real construction condition using GLD program.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.86-93
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• 2006

유출지하수나 지표수를 열원으로 지열히트펌프의 지초자료로 활용하기 위하여 Pond Loop형 열교환기를 설계, 제작하여 유동이 없는 수조 내에서 수조의 온도가 변화함에 따라 일정한 열교환기 입구온도를 유지하면서 열전달량을 측정하였다. 그 결과 수조를 Heat Source로 사용하는 경우 $5,500{\sim}4,500kcal/h$의 열량이 전달되었고 수조를 Heat Sink로 사용할 경우 $5,200{\sim}3,500kcal/h$의 열량이 전달되었다. 또한 열교환기 관내 유속이 증가함에 따라 열전달량이 증가하는 경향성을 확인할 수 있었고 이는 동시에 열교환기 입출구의 차압을 증가시킴을 알 수 있었다. 열교환기의 설계단계에서 사용하였던 열전달관계식으로 구한 총괄열전달계수, U와 실험값을 통해 유추한 U값을 비교한 결과 실험에 의해 유추된 U값이 $24{\sim}27%$ 설계치보다 크게 나타났다. 본 연구를 통하여 유출지하수 뿐만 아니라 하수 및 하천수를 이용한 지열히트펌프의 기초자료를 확보할 수 있었다.

• Journal of IKEEE
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• v.23 no.2
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• pp.474-478
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• 2019

In this paper, we analyze the degradation of receiving sensitivity due to the coupling between digital noise and mobile handset antenna using characteristic mode. First, we analyze the coupling mechanism between the antenna and digital noise, and analyze the role of the decoupling capacitor of the ground signal line, which is one of the ways to improve the antenna receiving sensitivity degradation due to camera noise. For the analysis, the digital signal line and the ground line of the FPCB of the camera module are modeled as a loop type feeder that excites the characteristic mode of the PCB ground, and improved model which has a ground line with a capacitor are analyzed.

• Journal of IKEEE
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• v.23 no.3
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• pp.873-877
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• 2019

In this paper, we analyze the degree of digital noise coupling for Inverted F Antenna (IFA) and Loop Antenna, which are representative types of portable terminal antenna, using characteristic mode. Firstly, the degree of coupling according to the direction of digital signal lines and characteristic mode current of the printed circuit board (PCB) including the antenna is compared and analyzed, and based on this result, the coupling between WiFi antenna and the front camera noise is analyzed. For analysis, the digital signal line and ground line of the FPCB of the camera module are modeled as a loop feeder that excites the characteristic mode of the PCB ground and the change of noise coupling according to the antenna types are analyzed.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.93-106
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• 2010

In performing a series of in-situ thermal response tests, the effective thermal conductivities of six vertical closed-loop ground heat exchangers were experimentally evaluated and compared one another, which were constructed in a test bed in Wonju. To compare thermal efficiency of the ground heat exchangers in field, the six boreholes were constructed with different construction conditions: grouting materials (cement vs. bentonite), different additives (silica sand vs. graphite) and the shape of pipe-sections (general U-loop type vs. 3 pipe-type). From the test results, it can be concluded that cement grouting has a higher effective thermal conductivity than bentonite grouting, and the efficiency of graphite better performs than silica sand as a thermally-enhancing addictive. In addition, a new 3 pipe-type heat exchanger provides less thermal interference between the inlet and outlet pipe than the conventional U-loop type heat exchanger, which results in superior thermal performance. Based on the results from the in-situ thermal response tests, a series of economic analyses have been made to show the applicability of the new addictives and 3 pipe-type heat exchanger.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.551-558
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• 2012

This paper presents a dual band loop-type ground antenna using lumped-elements that control the impedance bandwidth and resonant frequency. The dual-band operation of the proposed antenna is realized by inserting an additional resonated loop feed structure into the reference ground antenna. As the proper value of the capacitor and the inductor are chosen, the impedance bandwidth of our antenna with voltage standing wave ratio(VSWR) equal to 3 is 85 MHz and 725 MHz at the 2.45 and 5.5 GHz frequency band, respectively. Its validity is demonstrated via both the computed and measured results. Good antenna patterns and efficiencies are achieved at the dual frequency bands, as well as the physically small antenna element size($10{\times}5mm^2$).

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.423-428
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• 2007

This study was performed to construct a geothermal data base about thermal conductivity of ground heat exchanger and thermal properties of grouting material which used to refill the borehole. We have acquired geothermal data sets from 39 sites over wide area of South Korea except to Jeju island. From data analysis, the range of thermal conductivity is 1.5$\sim$4.0 W/mK. It means that thermal conductivity varies with grouting material as well as regional geology and ground water system.