• Title/Summary/Keyword: Buried Type

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Analysis of the Potential Rises near Grounding Electrodes using Semisplere type scale Model (반구형 축소모델을 이용한 접지전극 주변의 전위상승 분석)

  • Lee, B.H.;Beak, Y.H.;Li, F.;Kim, K.B.
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.05a
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    • pp.259-262
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    • 2008
  • This paper describes the ground surface potential profiles near the object to be grounded. The hemisphere water tank was used to simulate the. scale model. As a result, the ground surface potential near the ground electrode was considerably raised. In particular the ground surface potential at the just upper part of ground rod was higher than other part. The ground surface potential was lowered with increasing the buried depth of ground rod.

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Floor Heating Characteristics of Latent Heat Storage - Bioceramic Ondol - Focused on Theoretical Analysis - (잠열 축열 - 바이오 세라믹 온돌의 난방 특성 - 이론적 분석을 중심으로 -)

  • 송현갑;유영선
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1995.05a
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    • pp.213-222
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    • 1995
  • Korean traditional Ondol with the sensible heat storage medium has been for a long time used as residential heating system, in these days the concrete Ondol without the heat storage medium was realized as the heating system in the private houses and the apartments. This floor heating system is good for our health. But the concrete Ondol is not desirable for the energy saving and for the maintenance of comfortable room temperature because the heat storage medium is not employed in the concrete Ondol. And as the hot water circulating pipes ate buried under the the concrete floor, the concrete Ondol system has some kind of problems to be improved. Therefore the new type of Ondol system was developed in this study. And the new Ondol was consisted of latent heat storage material as heat storage medium with a great heat capacity and bioceramics as medium to maintain comfortable room temperature. In this study, the heat transfer characteristics of latent heat storage-bioceramic Ondol was analyzed theoretically.

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Fabrication of a Micromachined Metal Thin-film Type Pressure Sensor for High Overpressure Tolerance and Its Characteristics (과부하 방지용 마이크로머시닝 금속 박막형 압력센서의 제작과 그 특성)

  • Kim, Jae-Min;Lim, Byoung-Kwon;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.05a
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    • pp.192-196
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    • 2002
  • This paper describes on the fabrication and characteristics of a metal thin-film pressure sensor based on Cr strain-gauges for harsh environment applications. The Cr thin-film strain-gauges are sputter-deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Cr thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097~1.21 $mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

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A Study of Optimization Design for Buried type Permanent Magnet Synchronous Generator (영구자석 내삽형 동기 발전기의 최적화 설계에 관한 연구)

  • Lee, Kwang-Ho;Kwon, Hyuk-Ki;Hong, Sun-Ki
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.868-869
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    • 2007
  • 자여자식 동기 발전기에 비해, 영구자석 내삽형 동기 발전기는 순간적인 부하 단락 시에도 지속적으로 여자기에 여자 전원을 공급할 수 있어 큰 부하 변동에도 안정적으로 발전기를 운전할 수 있게 해 준다. 본 연구에서는 이러한 전동기의 해석 프로그램을 개발하고, 이로부터 유전알고리즘을 이용하여 설계프로그램을 개발하였다. 영구자석동기 발전기의 목적함수를 효율로 두었으며, 발전기의 형상을 변화시켜 제약 조건을 만족하는 최대 효율을 갖는 1kW급 영구자석 내삽형 동기 발전기의 설계치를 제시하였다.

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A Study on Heat Transfer Performance of Vertical Ground Heat Exchanger of GSHP(Ground Source Heat Pump) (GSHP용 수직형 지중열교환기의 열전달 성능에 관한 연구)

  • Chung, Min-Ho;Chang, Ki-Chang;Ra, Ho-Sang;Baik, Young-Jin;Park, Seong-Ryong;Yoo, Seong-Yeon
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2102-2107
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    • 2007
  • GSHP systems are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal and vertical type according to the installation method. Vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double u-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

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Module-Type Switching Rectifier for Cathodic Protection of Underground and Maritime Metallic Constructions (지하매설 및 해양 금속구조물 음극방식용 모듈 타입 스위칭 정류기)

  • 문상호;김보경;김인동;노의철;권영원;정성우;임헌호
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.6
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    • pp.570-578
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    • 2002
  • Cathodic protection is widely used to prevent corrosion of steel materials buried in the underground and sea. As a rectifier for cathodic protection, the conventional phase-controlled rectifiers have been used so far in spite of such shortcomings as large volume, heavy weight and floor power factor. In order to overcome such disadvantages, this paper proposes a new module-type switching rectifier for cathodic protection, which is composed of two parts, namely, AC/DC converter and module- type DC/DC converter. The AC/DC converter is a single-phase IGBT PWM rectifier, thus resulting in almost unity power factor and controlled DC output voltage. The module-type DC/DC converter operates under ZVS/ZCS switching condition to permit high frequency switching operation. It enables to use high-frequency transformer for electrical isolation, thus reducing volume and weight of overall system and improving system efficiency. It should be anticipated that the proposed rectifier techniques apply to the similar technical areas.

The Resistance Characteristics and Reliability Evaluation of an Insulation Ring Type of Corrugated Stainless Steel Tubing(CSST) (절연링형 금속플렉시블호스(CSST)의 저항 특성 및 신뢰성 평가)

  • Lee, Jang-Woo;Kim, Jeom-Sik;Choi, Chung-Seog
    • Journal of the Korean Society of Safety
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    • v.31 no.6
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    • pp.25-31
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    • 2016
  • This paper has analyzed the structure, applicable regulations and the resistance characteristics of insulation ring type of CSST (Corrugated Stainless Steel Tubing for Gas). With the flammability test conducted in accordance with KS C IEC 60811-1-1, the evaluation of insulation resistance, temperature characteristics, and reliability has been conducted. An insulation ring type CSST consists of protective coating, tube, nut, insulation ring, packing, socket, and ball valve. Connecting an insulation ring type CSST to gas tubings for gas appliance is not permitted, moreover, the product shall be installed inside a sleeve pipe in case of buried installation such as the ceiling. Damages on protective coating and tube were detected when fire was applied to the test sample with a portable torch for 60 seconds. The insulation resistance of a normal product was $49.59M{\Omega}$, while that of the product completed the flammability test reduced to $9.21M{\Omega}$. The mean insulation resistance within the confidence Interval of 95% using the mini tap program 17 was $49.59M{\Omega}$ and the mean insulation resistance within the confidence interval reduced to $9.21M{\Omega}$. In the normal distribution analysis of 95% confidence interval, the value-P of the normal product was stable at 0.075 and AD(Anderson-Darling) statistic value was turned out to be 0.063, which is very normal, and the standard deviation was analyzed as 0.2586. The value P of the product completed the flammability test resulted in 0.005, the AD was 1.355 and the standard deviation reduced to 0.07908.

A Study on the Optimized Installation of Gas Storage Tank through Pugh Method (퓨 방법을 통한 최적의 저장탱크 시공에 관한 연구)

  • Huh, Yong Jeong;Lee, Jong Rark;Lee, Seon Yeong;Leem, Sa Hwan
    • Journal of the Korean Institute of Gas
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    • v.18 no.4
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    • pp.8-12
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    • 2014
  • The aim of this study is achieving customer satisfaction by finding cost-effective installation of storage tanks in the gas filling stations. Pros and cons were measured by comparison between above and underground tanks using Pugh methods. In particular, severe problems regarding gas safety are expected to be resolved by reducing the frequency of gas accidents occurred in mass storage facilities. To this end, we have used Pugh's method to compare the advantages and disadvantages of the existing storage tanks-Ground above type and underground type. After the analyses, it is shown that underground containment storage tank can provide the highest degree of safety and Real estate among Ground above type, Underground buried type and underground containment type storage tanks.

The Structual Restoration on Gyeongju-Style Piled Stone-Type Wooden Chamber Tombs (경주식 적석목곽묘의 구조복원 재고)

  • Gweon, Yong Dae
    • Korean Journal of Heritage: History & Science
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    • v.42 no.3
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    • pp.66-87
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    • 2009
  • The definition of the structure of wooden chamber tomb(piled stone-type) is as follows. It is a tomb with wooden chamber, and stones were piled on top of the wooden chamber, and then a wooden structure was placed on top of the piled stones, and more stones were piled on top of the wooden structure, and sealed with clay. Of course this definition can vary according to periods, the buried, etc. Gyeongju-style piled stone type wooden chamber tombs have some distinguished characteristics compared to general definition of piled stone type wooden chamber tombs. Outside the wooden chamber, either stone embankments or filled-in stones were layed out, and pilet-in stones are positioned right above the wooden chamber, and almost every class used this type, and finally, it is exclusively found in Gyeongju area. First generations of this Gyeongju-style piled stone type wooden chamber tombs appeared in first half of 5th century. These tombs inherited characteristics like ground plan, wooden chamber, double chamber(inner chamber and outer chamber), piled stones, burial of the living with the dead, piled stones, from precedent wooden chamber tombs. However these tombs have explicit new characteristics which are not found in the precedent wooden chamber tombs such as stone embankments, wooden pillars, piled stones(above ground level), soil tumuluses. stone embankments and wooden pillars are exclusively found on great piled stone type above-ground level wooden chamber tombs such as the Hwangnamdaechong(皇南大塚). Stone embankments, wooden pillars, piled stones(above ground level) are all elements of building process of soil tumuluses. stone embankments support outer wall of above-ground level wooden chambers and disperse the weight of tumuluses. Wooden pillars functioned as auxiliary supports with wooden structures to prevent the collapse of stone embankments. Piled stones are consists of stones of regular size, placed on the wooden structure. And after the piled stones were sealed with clay, tumulus was built with soil. Piled stones are unique characteristics which reflects the environment of Gyeongju area. Piled stone type wooden chamber tombs are located on the vast and plain river basin of Hyeongsan river(兄山江). Which makes vast source of sands and pebbles. Therefore, tumulus of these tombs contains large amount of sands and are prone to collapse if soil tumulus was built directly on the wooden structure. Consequently, to maintain external shape of the tumulus and to prevent collapse of inner structure, piled stones and clay-sealing was made. In this way, they can prevent total collapse of the tombs even if the tumulus was washed away. The soil tumulus is a characteristic which emerges when a nation or political entity reaches certain growing stage. It can be said that after birth of a nation, growing stage follows and social structure will change, and a newly emerged ruling class starts building new tombs, instead of precedent wooden chamber tombs. In this process, soil tumulus was built and the size and structure of the tombs differ according to the ruling class. Ground plan, stone embankments, number of the persons buried alive with the dead, quantity and quality of artifacts reflect social status of the ruling class. In conclusion, Gyeongju-style piled stone type wooden chamber tombs emerged with different characteristics from the precedent wooden chamber tombs when Shilla reached growing stage.

A Study on Adequacy of Pipe Deterioration Evaluation Methods using the Endoscope of Water Distribution Pipe (배수관 내시경 조사를 통한 간접적인 관 노후도 평가방법의 적정성 연구)

  • Choi, Tae Ho;Kang, Sin Jae;Choi, Jae Ho;Koo, Ja Yong
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.5
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    • pp.669-683
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    • 2012
  • The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration.