• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.841-846
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• 2008

Recently the LNG(liquified natural gas) public buses have been introduced to prevent the air pollution in metropolitan areas. As the LNG temperature in fuel tank is as low as $-162^{\circ}C$. the thermal and structural effects of tank components need to be studied for safe introduction in the market. Especially the support system of LNG fuel tank in vehicle, which has connected with inside and outside of tanks, should put attention to reduce the structural stress due to cryogenic temperature and to restrict the heat flux from ambient. There are two supporting systems in the tank, that one is connected between inside and outside tanks by welding, and the other is the inserted support system which is a cylindrical SUS bar inserted in a hole of the supporting plate. In this study the temperature distribution and thermal stress of the inserted support system were evaluated by using the utility program as ANSYS. The results showed that the rate of heat transfer to inner tank through this support system was quite small due to limited contact of support bar with plate. but the thermal stress of support plate was obtained beyond the limited tensile value of SUS304. The cautious design for the support plate part, therefore, should be given to make the safe support system of LNG vehicle fuel tank.

• Solar Energy
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• v.6 no.2
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• pp.3-14
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• 1986

It is desirable to collect the solar thermal energy at relatively high temperature in order to minimize the size of thermal storage system and to enlarge the scope of solar thermal energy utilization. In this study, to develop a solar collector that has both advantages of collecting solar thermal energy at high temperature and fixing conveniently the collector system for long term period, a cylindrical parabolique concentrating solar collector (M.C.P.C.S.C) was designed, which has several rows of parabolique reflectors and thin thickness such as the flat-plate solar collector, maintaining the optical form of concentrating solar collector. The thermal performance of the M.C.P.C.S.C. newly designed in this study was analysed theoretically and experimentally. The results are summarized as follows: 1) prediction equation for outlet temperature, $T_o$, of heat transfer fluid and for the thermal efficiency, ${\eta}$, of the collector were derived as; o $$T_o=[C+B1_n(\frac{I_c(t)}{pv^3})]T_i$$ o $${\eta}=\frac{A}{A_c}\dot{m}[(C-1)+B1_n(E{\cdot}di^6\frac{I_c(t)}{\dot{m}^3})]\frac{T_i}{I_c(t)}$$ 2) When the insolation on the tilted solar collector surface, $I_c$, was $900-950W/m^2$ and the heat transfer fluid was not circulated in tubular absorber, the maximum temperature on the absorber surface was $100-118^{\circ}C$, this result suggested that the heat transfer fluid could be heated up to $98-116^{\circ}C$. The maximum temperature on the absorber surface was decreased with the increase of the collector shape factor, $L_p/L_w$ 3) There was a good agreement between the experimental and theoretical value of solar collector efficiency, ${\eta}$, which was proportional to the collector shape factor, $L_p/L_w$ 4) It is desirable to continue the study on the relationship between the collector shape factor, $L_p/L_w$, and the thermal efficiency of solar collector.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.201.2-201.2
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• 2016

The triggered vacuum switch (TVS) is widely used as a high power switch in the field of pulsed power application. TVS can produce current of higher than 100 kA within a microsecond after being triggered. A triggering high voltage pulse generator supplies a high voltage signal to the trigger system to initiate the discharge between a trigger pin and one of main electrode. The trigger system, which consists of a tungsten trigger electrode and cylindrical ceramic insulator around it, is normally installed at the center of main cathode electrode. The discharging characteristics of the trigger system strongly depend on the geometry, electrode material, vacuum pressure and so on. In addition, we especially will focus on the developing a triggering pulse generator, which can vary not only value of voltage but also pulse duration, because its properties gives pivot influences on the TVS discharge. To verify such effects, we made a 3.3 kJ TVS set-up initially. Thus we will discuss some of prominent results from 3.3 kJ TVS system. In parallel we will show on the design of 300 kJ TVS system for the high current in the future.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.233-239
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• 1999

Recently, a second generation composite resin system(ceromer) was introduced with significantly improved mechanical properties. The purpose of this study was to compare a ceromer with the other restorative materials and to assess its clinical usefulness. In this study, we used four restorative materials : amalgam (BESTALOY$^{(R)}$), indirect composite resin (Clearfil CR Inlay$^{(R)}$), ceromer (Targis$^{(R)}$) and ceramic (Vintage$^{(R)}$). And then we devided into four groups. The materials of each group were as follows : Amalgam group : BESTALOY$^{(R)}$ (Dong Myung Dental Industrial Co.) Composite Resin group : Clearfil CR Inlay$^{(R)}$ (Kuraray) Ceromer group : Targis$^{(R)}$ Dentin (Ivoclar-Vivadent) Ceramic group : Vintage$^{(R)}$ (Shofu Inc.) According to the above classification, we made samples through the polymerization of BESTALOY$^{(R)}$, Clearfil CR Inlay$^{(R)}$ and Targis$^{(R)}$ with separable cylindrical metal mold and firing of Vintage$^{(R)}$ in a investment mold. And then, we measured and compared the value of compressive strength, diametral tensile strength and Vicker's microhardness of each sample. The results were as follows : 1. Amalgam showed the highest value of compressive strength (390.37${\pm}$42.22MPa) and the value of ceromer was somewhere between ceramic and indirect composite resin. There were significant differences among the experimental groups(p<0.001). 2. Indirect composite resin showed the highest value of diametral tensile strength (74.21${\pm}$15.33MPa) and there was no significant difference with ceromer. Ceromer was higher diametral tensile strength than amalgam and ceramic (p<0.001). 3. Ceramic showed the highest value of microhardness (538.44${\pm}$37.38Hv) and the value of ceromer was somewhere between ceramic and indirect composite resin. There were significant differences among the experimental groups (p<0.001).

• The Transactions of the Korea Information Processing Society
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• v.5 no.1
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• pp.111-118
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• 1998

The density of fabric is a very important parameter in many fabric production processes. However, in the textile fabrication factories, textile density measurement process has been done inefficiently by handicraft. Thus, exact textile density measurement process is necessary to fabricate high quality textile through weft straighten. In this paper, we propose an automatic textile density measurement system to measure textile density automatically and to improve fabrication efficiency. The proposed system uses cylindrical lens to optically scan the weftl information of the fabric as well as convex lens to enlarge the weft images. The proposed system improves textile quality and provides constant density value to the whole textile range in the high speed fabrication process.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.167-175
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• 2021

Reusing electric vehicle batteries after they have been retired from mobile applications is considered a feasible solution to reduce the demand for new material and electric vehicle costs. However, the evaluation of the value and the performance of second-life batteries remain a problem that should be solved for the successful application of such batteries. The present work aims to estimate the remaining useful life of Li-ion batteries through the neuro-fuzzy system with the equivalent circuit parameters obtained by Electrochemical Impedance Spectroscopy (EIS). To obtain the impedance spectra of the Li-ion battery over the life, a 18650 cylindrical cell has been aged by 1035 charge/discharge cycles. Moreover, the capacity and the parameters of the equivalent circuit of a Li-ion battery have been recorded. Then, the data are used to establish a neuro-fuzzy system to estimate the remaining useful life of the battery. The experimental results show that the developed algorithm can estimate the remaining capacity of the battery with an RMSE error of 0.841%.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1199-1205
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• 2011

In the present work, a seat suspension system adopting semi-active damper is evaluated for driver's ride quality. A cylindrical type of ER(electrorheological) damper is designed and manufactured for the seat suspension of heavy vehicles. The governing equation is derived under consideration of human vibration. A sliding mode controller is then synthesized and experimentally realized on the manufactured ER seat suspension while a driver is sitting on the controlled seat. Ride quality is evaluated by fatigue decreased proficiency boundary, vibration dose value and crest factor utilizing weighted-acceleration according to ISO2631.

• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.160-165
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• 1998

This paper describes a method for field analysis inside the flat-type brushless DC motor using 2-D field simulator. Rigorous field analysis entail 3-D analysis. However, this analysis is not often appropriate for system designs because of the time and cost involved. For field analysis in this study, the 3-D problem is reduced to a 2-D boundary value problem by introducing a cylindrical cutting plane at the mean radius of the magnets. Independent of sizes and shapes of systems, the exact 2-D field results can be obtained with reasonable predictability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.7
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• pp.905-914
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• 1998

View factor determination is very important in thermal analysis problems with surface radiation but it is very difficult to determine view factors for complex geometries. Exact calculation of view factors for crystal growth furnace is essential due to not only its high surface temperature but the radiation shield, complicated heating system. In this study, view factor calculation algorithm is introduced and applied to cylindrical crystal growth furnace. This algorithm is based on the Hemi-Cube Algorithm and the results obtained with this algorithm show good agreements with those of analytical solution. As an application of this algorithm, temperature profiles and heating value distributions for various furnaces are calculated and the shape criteria for better furnace are suggested.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.15-21
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• 2017

In the active SONAR system, various studies have been carried out to enhance the resolution of a received signal. In order to obtain higher resolution for detecting a bottoming cylindrical object, the design of a planar array for SONAR is investigated in this paper. It is necessary to employ planar structures for SONAR array to obtain narrower beam pattern which gives high resolution. In this study, the transmit frequency of each acoustic transducer, which consists of an array is 13 kHz. For efficient detection of a target of an asymmetric size, the concept of areal angle is applied, which considers resolution according to both azimuth and elevation angles in array design. In the design, the areal angle is first investigated to satisfy the resolution requirements, and then based on the value of areal angles, the azimuth angle and the elevation angle are calculated respectively to design an array.