• Title/Summary/Keyword: air tightness

Search Result 121, Processing Time 0.034 seconds

Characteristics of Injection Molding in Optical Fiber Splice Closure (광섬유 케이블 접속함체의 사출성형 특성 분석)

  • Choi, Jaeyoung;Hong, Minsung
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.25 no.6
    • /
    • pp.434-439
    • /
    • 2016
  • Optical fiber splice closure serves to protect connection parts from external environment. Moreover, it functions as a connection, junction, and distribution in diverse surroundings such as aerial, underground, duct, and pole. In this research, first, the optical fiber splice closure, its configuration, and the design problem were briefly investigated. Second, the design and application for in-line cable closure were studied to satisfy its construction and technical features. The injection molding conditions and optimal design were conducted to save time and cost during the manufacturing process. Third, methods to minimize loss via of optical fiber cable while strongly fixing optical fiber cable with optical cable holder to prevent fracture were researched, and tests such as perfect air tightness and mechanical and environmental performance were conducted.

Underground Storage of Food (농수산물 및 식품의 지하 저장)

  • 신희순;권광수
    • Tunnel and Underground Space
    • /
    • v.4 no.2
    • /
    • pp.192-200
    • /
    • 1994
  • Underground offers many advantages for storing agricultural and marine products. Since it is confined by thick walls of rock it is easy to control temperature and humidity and to achieve air and water tightness. Also, damages by rodents and insects could be avoided. Flexibility in choosing the location is another advantage that underground could offer. Consequently the goods could be stored near the big city to meet the demand change. Because of these advantages, many underground food storage facilities were built and operated successfully in U.S. and many Euroupean countries. On the other hand, there is no underground food storage facilities in Korea despite the need is growing rapidly. This paper describes the case studies of foreigh food storage and technologies related to food storage were analyzed and evaluated. Also performed is analysis of domestic technologies for construction and operation of underground food storage facilities to deduce the fields of studies that have to be conducted.

  • PDF

Development of Nano Ceramic Structures for HEPA Type Breathing Wall (HEPA Filter형 숨쉬는 벽체용 나노세라믹 여재개발)

  • Kim, Jong-Won;Ahn, Young-Chull;Kim, Gil-Tae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.20 no.4
    • /
    • pp.274-279
    • /
    • 2008
  • In the perspective of saving energy in buildings, high performance of insulation and air tightness for improving the heating and the cooling efficiency has brought the positive effect in an economical view. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and it is also very harmful to residents because they spend over 90% of their time in the indoor area. Therefore, the ventilation is important to keep indoor environment clean and it can also save energy consumption. In this study, a HEPA type breathing wall is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. To make fine porous structures, polymer nano fibers which were made by electro spinning method are used as a precursor. The nano fibers are coated with SiO2 nano particles and finally the HEPA type breathing wall is made by sintering in the electric furnace at $300\sim500^{\circ}C$. The pressure drops of nano ceramic structure are 8.2, 25.5 and 44.9 mmAq at the face velocity of 2.0, 5.9 and 8.8 cm/s, respectively. Also the water vapor permeability is $3.6g/m^2{\cdot}h{\cdot}mmHg$. In this research, the porous nano ceramic structures are obtained and the possibility for the usage of a material for HEPA type breathing wall can be obtained.

FEA(Finite Element Analysis) Study for Electronic Hydrogen Regulator of Confidentiality Improvement (전자식 수소레귤레이터 기밀성 향상을 위한 FEA 연구)

  • Son, Won-Sik;Song, Jae-Wook;Jeon, Wan-Jae;Kim, Seung-Mo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.20 no.9
    • /
    • pp.175-181
    • /
    • 2019
  • In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

Analysis and Investigation of International(UIC, EN, IEC) and Domestic Standards(Test Methods) for Climatic Wind Tunnel Test of Rolling Stock (철도차량 기후환경시험을 위한 국제 규격(UIC, EN, IEC) 및 국내 규격(시험방법) 분석 및 고찰)

  • Jang, Yong-Jun;Chung, Jong-Duk;Lee, Jae-Cheon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.12
    • /
    • pp.782-789
    • /
    • 2020
  • The demand for the development of rolling stock technology to maintain the best performance in various climatic environments has increased to expand the overseas market of rolling stock. In this study, international and domestic standards that must be applied to build a harsh climatic environment test system were investigated and compared. The way of improvement for domestic standards is proposed. The wind velocities and temperatures are specified in the UIC, EN, and IEC standards for climatic wind tunnel, and EN 50125-1 provides the velocity test up to 180km/h, the largest wind speed. UIC and EN provide the lowest temperature of -45℃, and IEC 62498-1 provides the highest temperature 55℃. The solar radiation test was specified up to 1200W/m2 in the UIC, EN, and IEC. The IEC, EN, and KS R 9145 provide the water tightness standards, which are different from each other in water capacity, pressure, and methods. The snow test method was not well specified. KRTS-VE-Part 31 provides pressurization test methods. The airtightness standards for high-speed rolling stock are defined and regulated for internal pressure change rate in UIC 660 and 779-11. The domestic standard for the wind tunnel test was not well prepared, and the solar radiation test and snow test do not exist in Korea. Therefore, it is necessary to improve domestic standards to an international level for the climatic wind tunnel test of rolling stock.

The Individual Heat-recovery ventilation system of Residential Buildings (주거용 건물의 개별 환기시스템 필요성에 관한 연구)

  • Shin, U-Cheul;Lee, Wang-Je;Yoon, Jong-Ho;Baek, Nam-Choon
    • KIEAE Journal
    • /
    • v.14 no.6
    • /
    • pp.99-104
    • /
    • 2014
  • Recently supply of low energy house is increasing which can enhance energy efficiency and indoor environment comfort. Low energy house have to secure air tightness as well as thermal performance so house become high airtightness and inevitably need heat recovery ventilator to enhance indoor air quality. However, most of current ventilation systems are one-click, controlling the entire space so it causes increasing of heating load and fan power which makes it hard to save energy. Thus, Individual Control system is required which can achieve both enhancing indoor air quality and decreasing heating load and electric fan power. Thereby, in this study, we analyzed the correlation between ventilation and fan power through mock-up experiment and measured ventilation load under individual control system. As a result, under the condition of $24^{\circ}C$ of indoor temperature for 6 month(November to April) in Daejeon, ventilation load by fan speed was $10.9{\sim}19.6kWh/m^2{\cdot}a$ when operated 24 hours and $7.6{\sim}13.7kWh/m^2{\cdot}a$ when operated 12 hours in night time. In addition, it is possible to reduce at most 60% of ventilation load under the individual control system; measured ventilation load was $7.4kWh/m^2{\cdot}a$ when operated 24 hours, and $5.5kWh/m^2{\cdot}$ when operated 12 hours in night time.

Performance of Nano Ceramic Filter for the Removal of Ultra Fine Particles (초미세입자 제거를 위한 나노세라믹 필터의 성능 평가)

  • Kim, Jong-Won;Ahn, Young-Chull;Yi, Byeong-Kwon;Jeong, Hyeon-Jae
    • Proceedings of the SAREK Conference
    • /
    • 2009.06a
    • /
    • pp.751-756
    • /
    • 2009
  • In the perspective of saving energy in buildings, the high performance of insulation and air tightness for improving the heating and the cooling efficiency, has brought economically positive effects. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and is also very harmful to the residents, because they spend over 90% of their time indoors. Therefore, the ventilation is important to keep the indoor environment clean and it can also save the energy consumption. In this study, a HEPA type nano ceramic filter is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. The double layer filter, which has $30{\mu}m$ in diameter at the conditions of 10wt% of concentration and 3kV/cm of the electric intensity, is produced by electrospinning. The filtration coating technology is confirmed in the solution with $SiO_2$ nano particles using polymer nano fibers. Also double layer filters are coated with $SiO_2$ nano particles and finally the porous construction materials are made by sintering in the electric furnace at $200{\sim}1400^{\circ}C$. The efficiency is measured 96.67% at the particle size of $0.31{\mu}m$, which is slightly lower than HEPA filter. However the efficiency is turned out to be sufficient.

  • PDF

A STUDY ON THE MINIMUM CROSS-SECTIONAL AREA OF HIGH-SPEED RAILWAY TUNNEL SATISFYING PASSENGER EAR DISCOMFORT CRITERIA (승객 이명감 기준을 만족하는 고속철도 터널 최소 단면적에 대한 연구)

  • Kwon, H.B.
    • Journal of computational fluids engineering
    • /
    • v.20 no.3
    • /
    • pp.62-69
    • /
    • 2015
  • Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from $50m^2$ to $120m^2$. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

Functional Analysis of Subsystem for Electric Plug Door (전기식 플러그 도어 하부시스템 기능 분석)

  • Joung, Eui-Jin;Hong, Jai-Sung;Won, Jong-Un;Lee, Jang-Mu;Lee, Han-Min;Kim, Gil-Dong
    • Proceedings of the KIEE Conference
    • /
    • 2011.07a
    • /
    • pp.2198-2199
    • /
    • 2011
  • The sliding door and plug door are the main types of door system in the EMU(Electric Multiple Unit). The sliding door is widely used in Korea but has weak point in the noise problem. In the low operation speed, the noise coming from outer side of the EMU is not an important factor. As the speed is higher than before, noise is increased and make an issue. The main cause of noise is the imperfect air tightness in the EMU. The plug door system has advantages for the noise reduction characteristic in the high speed area. Actually the noise level is an important factor for the passenger comfort. In this paper, we will describe the characteristic of electric plug door and functions of sub component.

  • PDF

Numerical Modeling of Fuel Cell Gasket for Sealing Performance (연료전지 스택의 기밀성 향상을 위한 가스켓 모델링과 해석 기법)

  • Kim, Heon-Young;Kim, Jung-Min;Kim, Dae-Young;Suh, Jung-Do;Yang, Yoo-Chang;Im, Cheol-Ho
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2007.06a
    • /
    • pp.97-100
    • /
    • 2007
  • Fuel Cell Stack performance, which is influenced by the maintenance of a constant internal environment, requires high levels of air tightness. Used for analysis, gasket for fuel cell is made of elastic rubber materials and placed over separator, and shape of deformation of a gasket affects the transformation separator and airtightness while fastening structure. Separator as made of steel sheet isn't broken under pressure but can affect gas and cool water flow by the plastic deformation process. Therefore, it is understood that assembly process is well developed in case distribution of stress and shape of deformation is shown uniformly. This study is conducted on the assumption that a fuel cell maintenance is advantageous in that conditions. In this paper, analyses of unit cell and partial model were performed and distribution of stress and shape of deformation of Gasket and separator were analyzed to evaluate the airtightness while fastening structure.

  • PDF