• 한국산업융합학회 논문집
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• 제21권1호
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• pp.1-8
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• 2018

The purpose of this study is to develop a high-strength, high-toughness, thin-walled aluminum shock absorber housing product by applying a high vacuum die casting method to improve internal gas defect and formability. The analysis program dedicated for the casting was used because it was too costly and time-consuming to adopt the gating system design. The final casting plan was designed based on the flow pattern of the material filled into the mold and the result of air pressure and air pocket after the material was completely filled in the mold. Gaty shape was designed as a split type. The runner was designed to have the same shape as the initial inlet curve of the cavity, and the flow of the molten metal was prevented from turbulent flow. The most favorable results were obtained when the injection speed was $V_2=4.0m/s$. Defects on pores were reduced by applying high vacuum level inside the mold.

• 한국주거학회논문집
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• 제8권3호
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• pp.219-230
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• 1997

Lack of technical standards, specification and inadequate execution in masonry wall construction in Korea lead to produce serious flaw problems such as crack, efflorescene, and upset etc.. The purpose of this paper is to present the practical details for Masonry cavity wall construction to prevent rain penetration and to accommodate differential movement between the inner and outer wythes of cavity walls. Considering rain penetration and differential movement of both wythes of cavity walls, provision of an adequate air space, an airtight back-up wall, clean cavity with weepholes and vents, properly positioned flashing, tie and shelf angle etc. depend on the cavity wall types will help ensure good performance. The present details included noncorrosive hot dip galvanized steel or stainless steel for metal components, plastic and ultra violet resistant polypropylene Copolymer for other components was taken into account the construction method and several types of cavity walls in Korea

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.546-560
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• 2000

This paper describes the design and evaluation of a noise suppressing hydrophone that is robust to external noise without sacrificing its performance as a receiver. To increase robustness of the receiver to the external noise, first, effects of location of external noise on its performance are analyzed with the finite element method (FEM). Based on the results, geometrical variations are implemented on the structure with additional air pockets and damping layers that work as acoustic shields or scatterers of the noise, and fourteen trial models are developed for the noise suppressing hydrophone structures. The results show that the effect of the external noise is most significant when it is applied to near the mid-side surface of the hydrophone housing. The external noise is isolated most efficiently when two thin damping layers combined with five air pockets are inserted to the circumference of the hydrophone housing. Overall, of the fourteen structural variations of the hydrophone, the best one shows about 87% reduction in the response of the original structure to external noise.

• Structural Monitoring and Maintenance
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• 제7권2호
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• pp.85-107
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• 2020

Dynamic responses of porous piezoelectric and metal foam nano-size plates have been examined via a four variables plate formulation. Diverse pore dispersions named uniform, symmetric and asymmetric have been selected. The piezoelectric nano-size plate is subjected to an external electrical voltage. Nonlocal strain gradient theory (NSGT) which includes two scale factors has been utilized to provide size-dependent model of foam nanoplate. The presented plate formulation verifies the shear deformations impacts and it gives fewer number of field components compared to first-order plate model. Hamilton's principle has been utilized for deriving the governing equations. Achieved results by differential quadrature (DQ) method have been verified with those reported in previous studies. The influences of nonlocal factor, strain gradients, electrical voltage, dynamical load frequency and pore type on forced responses of metal and piezoelectric foam nano-size plates have been researched.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.621-624
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• 1998

This paper presents a new configuration of dielectric bandpass filter using the comb-line filter design theory. This filter is composed of a homogeneous dielectric monoblock $(\varepsilonr=35.5)$ with two metal post and a dielectric sheet $(\varepsilonr=9.8).$ In this structure, the RF leakage is suppressed without other shield housing. For the fabricated filter, insertion loss value in the passband region was 0.9dB(Max.) and return loss value was 19dB(Min). Also, this filter has a attenuation pole in the stopband.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 박판성형기술의 진보
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• pp.191-198
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• 1994

A practical example of the axisymmetric deep drawing process is simulated by the elastic-plastic finite element analysis using updated Lagrangian approach considering the large deformation. An approach is suggested to solve the problem of the ductile fracture that may encounter during the deep drawing process. The result can be applied to the design of the die for the axisymmetric deep drawing.

• 한국주거학회논문집
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• 제20권1호
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• pp.101-112
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• 2009

The purpose of this study is to find out the preference and the needs of old womens on the life support appliances i.e. medication dispenser, video phone, activity monitor and sleep monitor. The appliances may be improved reflecting the result of the questionnaire asking about the preferred functions and designs. The respondents were 141 female seniors of 65 years and older, living in Ulsan city or Cheongju city, Korea. Following is the list of results. (1) The medication dispenser, responded as highly preferred, met some worries over the troubles by power stoppage especially while one is out, letting her forget the medication time. (2) The video phone was worried over the cases of hearing failure by small sound, and watching failure by weakening sight. (3) The activity monitor, like the medication dispenser, was worried about the troubles while one is out or out of the monitoring scope, its expense, and the privacy, (4) The sleep monitor met the worries over the inadequacy for the sleeping mat on the floor and the emission of electromagnetic waves. (5) The preferred designs were (1) white or red standing medication dispenser, (2) wall-mounted video phone working by voice, (3) metal activity monitor sensor with white or yellow bracelet.

• 한국주거학회논문집
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• 제13권2호
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• pp.47-53
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• 2002

The purposes of this study actually measure to the dimension and the quality of material play equipment's examine whether they meet safety standards or not, and intend to offer basic data to present proper safety standards concerning the dimension of play equipment in the end. The subjects for this study were 59 outdoor playgrounds, 30 among them located in apartment sites and the remainder did in residential districts. The time of actual measurement was in June 1999, and June 2000. Data were analyzed into frequency, percentage, mean, and standard deviation by using SPSSWIN program. The main results were as follows.: First, more than half of playgrounds were assessed for being traffic hazards due to the adjacent streets. And they were hardly equipped with the toilet and drinking water facilities, but were almost equipped with the shade of a tree and benches. Second, it was caused in inconvenience of children's use and difficulty of play equipments'management, since the quality of play equipments materials was consisted of wood or metal. Third, the standards for swing and slide were established in detail and actual measurement's results were suitable to standards'value as well, whereas the standards for seesaw and climber were not in detail and they did not design or install suitably.

• Design & Manufacturing
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• 제10권3호
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• pp.14-19
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• 2016

Thermally or electrically conductive filler reinforced polymer composites are extensively being developed as the demand for light weight material increases rapidly in industiral applications need good conductivity such as heat sink of the electronics or light. Carbon or ceramic materials like graphite, carbon nanotube or boron nitride are typical conductive fillers with good thermal or electical conductivity. Using these conductive fillers, the polymer composites in the market show wide range of thermal conductivity from approximately 1 W/mK to 20 W/mK, which is quite enhanced considering the thermal conductivity lower than 0.5 W/mK for most polymeric materials. The practical use of these composites, however, is yet limited to specific applications because most composites are still not conductive enough or too difficult to process, too brittle, too expensive for higher conductivity. For practical use of conductive composite, the thermal conductivity required depending on the heat releasing mode are studied first for simplified unit cooling geometry to propose thermal conductivities of the composites for reasonable cooling performance comparing with the metal heat sink as a reference. Also, as a practical design for heat sink based on polymer composite, composite and metal sheet hybrid structures are investigated for LED lamp heat sink and audio amplication module housing to find that this hybrid structure can be a good solution considering all of the cooling performance, manufacturing, mechanical performance, cost and weight.

• 토지주택연구
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• 제4권1호
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• pp.119-124
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• 2013

나노여과막은 일반적으로 하전막이며, 용질의 하전성, 막과의 상호작용에 의해서 특징 있는 분리특성을 보인다. 본 연구에서는 나노여과막에 의한 폐수 중의 중금속류의 제거에 미치는 하전특성을 조사했다. 크롬(Cr), 철(Fe), 구리(Cu), 아연(Zn), 비소(As), 주석(Sn), 납(Pb)을 각각 0.1mg/L 첨가한 모의폐수를 제조하여 나노여과막(a)와 나노여과막(b)를 이용하여 운전압력 0.24MPa, 온도 $25^{\circ}C$에서 여과실험을 수행하였다. 그 결과, 나노여과막(a)와 나노여과막(b)에 의한 염소 이온의 제거율은 12.8%, 3.5%였고, 황산이온의 제거율은 78%, 9.3%였고 TOC의 제거율은 70.4%, 26.2%이었다. 한편, 중금속의 제거율은 나노여과막(a)의 경우 크롬(Cr) 92.5%, 철(Fe) 90.9%, 구리(Cu) 93.1%, 아연(Zn) 92.6%, 비소(As) 74.6%, 주석(Sn) 97.3%, 납(Pb) 93.4%이었고, 나노여과막(b)의 경우는 크롬(Cr) 69.9%, 철(Fe) 84.6%, 구리(Cu) 87.0%, 아연(Zn) 73.3%, 비소(As) 15.2%, 주석(Sn) 80.1%, 납(Pb) 87.7%이었다. 여기서, 나노여과(a), 나노여과(b)의 경우 공통적으로 크롬, 철, 동, 아연, 주석, 납에 비하여 비소의 제거율은 상대적 낮았다. 상기 실험결과에서 폐수 중에 다량 함유되는 염소이온 및 황산이온에 대한 중금속류의 분리계수와 이온성분의 수중에서의 활동정도를 나타내는 인자인 이온 몰 전도도로 해석할 수 있었다. 그 결과, 몰 전도도 비가 큰 중금속 이온일수록, 나노여과막에 의한 중금속 이온의 제거율이 높아지는 경향을 알 수 있었다.