• 한국연초학회지
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• 제24권2호
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• pp.107-112
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• 2002

There are many combination with the porosity of tipping paper and plug wrap for a design of ventilation rate of cigarette. This study was carried out to determine the effect of a design of permeability of tipping paper and inner or outer of plug wrap on the ventilation rate of cigarette with constant pressure drop in column part and filter part. Our results indicated that the higher the plugwrap porosity, the higher the ventilation rate and the less variable of cigarette in case of mono filter. But, in case of duel filter, the ventilation rate of cigarette was depended on the manufacturing method of filter plug, even though using the same porous plug wrap on inner and outer of filter. We also found that the porosity of outer plug wrap was more effect on the ventilation rate than the porosity of inner plug wrap. As the high porosity of inner plug wrap compared with the porosity of outer plug wrap, the less variable of ventilation rate of cigarette in any combination of the porosity of plug wrap. When we used the higher porous outer plug wrap than inner plug wrap, the ventilation rate of cigarette was high. Also, the higher the inner plug wrap porosity, the less variable of ventilation rate of cigarette.

• 설비공학논문집
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• 제16권3호
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• pp.241-249
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• 2004

A parametric study on the scroll wrap configuration factors of a $CO_2$scroll compressor for heat pump water heater has been carried out. Since there are 7 scroll wrap design parameters and 5 equations relating them, two of the design parameters can be selected as independent parameters. In this study, the wrap thickness and orbiting radius are chosen as independent ones. Computer simulation program has been used to estimate the compressor performance at various combinations of the scroll wrap design parameters. It has been found that there exists optimum combination of the wrap parameters for the highest compressor performance over analyzed ranges of the design parameters.

• 한국정보통신학회논문지
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• 제11권7호
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• pp.1332-1340
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• 2007

본 논문에서는 휴대인터넷 와이브로 (WiBro) 시스템의 보안계층 중 암호 키 (Traffic Encryption Key; TEK)를 암호 복호하는 key wrap/unwrap 알고리듬의 효율적인 하드웨어 설계에 대해 기술한다. 설계된 key wrap/unwrap 코어 (WB_KeyWuW)는 AES (Advanced Encryption Standard) 알고리듬을 기반으로 하고 있으며, 128비트의 TEK를 128비트의 KEK (Key Encryption Key)로 암호화하여 192비트의 암호화된 키를 생성하고, 192비트의 암호화된 키를 복호화하여 128비트의 TEK로 복호하는 기능을 수행한다. 효율적인 하드웨어 구현을 위해 라운드 변환 블록에 하드웨어 공유기법을 적용하여 설계하였으며, 또한 하드웨어 복잡도에 가장 큰 영향을 미치는 SubByte/InvSubByte 블록을 체 변환 방법을 적용하여 구현하였다. 이를 통해, LUT (Lookup Table)로 구현하는 방식에 비해 약 25%의 게이트 수를 감소시켰다. Verilog-HDL로 설계된 WB_KeyWuW 코어는 약 14,300개의 게이트로 구현되었으며, 100-MHz@3.3-V의 클록으로 동작하여 $16{\sim}22-Mbps$의 성능이 예상되어 와이브로 시스템 보안용 하드웨어 구현을 위한 IP로 사용될 수 있다.

• 한국연초학회지
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• 제24권1호
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• pp.60-66
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• 2002

The ventilation rate of a ventilated filter cigarette depends on the details of its construction and on the properties of its components such as tobacco column pressure drop, filter pressure drop, tipping paper and plug wrap permeability, and vent position. Also, It was affected by the condition of adhesion of glue between tipping paper and plug wrap. This study was carried out to find the effect of surface properties of tipping paper and plug wrap, and a characteristics of glue on the ventilation rate of cigarettes. Our results indicated that the surface properties of tipping paper and plug wrap affected on the ventilation rate of cigarette. Also, the variation of ventilation rate was affected by the surface properties of tipping paper and the size of glue particles. We also found that the surface properties of tipping paper and plug wrap, and the emersion size of glue were the major factors to concern in the design for materials of cigarettes.

• 한국연초학회지
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• 제23권1호
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• pp.60-64
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• 2001

The variability of a ventilated filter cigarette depends on the details of its construction and one properties of its components and the variations in filter ventilation is effected by many factors such as tobacco column pressure drop, filter pressure drop, tipping paper and plug wrap permeability, and vent position. In this study, the effects of combination of tipping paper and plug wrap on filter ventilation of cigarettes were studied for the target ventilation level under the specific tobacco column and filter tip in order to reduce the variation of filter ventilation. When Nicolas Baskevitch\`s equation on filter ventilation was used to try out Monte Carlo Simulation, at the combination where tipping paper permeability is high and plug wrap permeability is low, even the small change in tipping paper and plug wrap permeability showed high variation of target ventilation level. Also, according to the analysis data of filter ventilation in cigarettes designed at the level of 45% filter ventilation by the combinations with tipping paper and plug wrap, the variation in cigarette filter ventilation was increased as increasing tipping paper permeability and decreasing plug wrap permeability. As the results of this study, the variation of filter ventilation can be reduced by increasing plug wrap permeability/tipping paper permeability ratio in the cigarette design, considering 2-3% of tipping paper permeability variation(%CV) and about 10% of plugwrap permeability variation.

• International Journal of Air-Conditioning and Refrigeration
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• 제16권4호
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• pp.124-129
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• 2008

Design practice has been made on an oil-less scroll air compressor as an air supply device for a 2 kW fuel cell system where air pressure of 2 bar and flow rate of 120 liter/min are required. Basic structure of the scroll compressor includes double-sided scroll wrap for the orbiting scroll driven by two crankshafts connected to each other by a timing belt. These features can eliminate thrust surface which otherwise would produce frictional heat and jeopardize reliable operation of the orbiting scroll and the scroll element's deformation as well. This study focuses on optimum scroll wrap design; orbiting radius has been chosen as an independent design parameter. As the orbiting radius changes, scroll sizes such as scroll base plate and discharge port diameters change accordingly. Gas compression-related losses and mechanical loss also change with the orbiting radius. With a scroll base plate diameter of 120mm at most and discharge port of at least 10mm, the orbiting radius should be within the range of 2.5-4.0mm. With this range of the orbiting radius, it was estimated by performance analysis that the compressor efficiency reached to a maximum of ${\eta}_c$=96% at the orbiting radius of $r_s$=3.5mm for the scroll wrap height-to-thickness ratio of h/t=5.

• 설비공학논문집
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• 제20권2호
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• pp.113-120
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• 2008

Potential application of the scroll type machine to air compressor for fuel cell has been studied. Among the seven configuration factors which determine scroll wrap profile, the wrap thickness and the orbiting radius were chosen as two independent variables to generate various scroll wrap profiles. A conceptual design practice was conducted for scroll air compressor for SOFC with power output of 2 kW. With larger wrap thickness and orbiting radius, base plate area of the orbiting scroll becomes smaller, so is the axial gas force acting on the base plate, resulting in reduced thrust loss in spite of larger friction velocity. Performance analysis on the designed model showed that its total efficiency was 64.4% with the mass flow rate per unit compressor input of 0.00905 kg/(s kW) for the wrap thickness of 3.5 mm and the orbiting radius of 3.0 mm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1450-1454
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• 2005

In this paper, the control strategy of the tension and speed based a prototype bio-wrap winding machine is developed. The decentralized control strategy using PID control algorithm applied for each subsystem is proposed to control the each system's desired outputs, because the tension of each subsystem effects that of next roll system. The computer simulations and the experiment results are presented to show that the proposed control scheme is feasible for a prototype bio-wrap winding machine.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 자동차부품 제작기술의 진보
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• pp.87-95
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• 1996

The stamping process consists of two stages : First, the blank is held by the blank holder and then it is further formed into the die cavity by punch stroke. In actual stamping process, the accurate prediction of binder wrap is an indispensable step in sheet metal forming analysis because the initial plastic buckling induced by improper die design is directly related with fatal defect at the final stage. In the present work, an approach including the gravity effect of blank material and proper consideration of contact and friction is proposed. Computations are carried out for some actual auto-body parts using 3D FEM code to investigate the validity of the proposed methodology. Comparisons with experimental results show that the suggested scheme can be effectively applied to the precise prediction of binder wrap for arbitrarily curved die faces in which gravity and contact effect must be taken into account.

• 한국정밀공학회지
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• 제13권1호
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• pp.69-77
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• 1996

To design high-effective profile in screw rotor profile using in screw compressor, we design the symmetric type changing the number of lobes and the non-symmetric type changing the neighbourhood of the top point of lobe. Then, we calculated the performance value of profile according to the scale of these non-symmetric's wrap angle. We had the results as follows. 1. About the non-symmetric case, the larger a wrap angle is the shorter seal line is and the smaller blow hole is, thus we know what the large wrap angle profile is better than the small one. 2. We know what the non-symmetric profile is better than the symmetric profile in the result of the compare of seal line's length, blow hole's area, volume curve. 3. About the non-symmetric case, the deformation of the neighbourhood of lobe's top point of the rotor profile has a large effect upon the increase of performance because the length of seal line became short and the area of blow hole is small.