• Tribology and Lubricants
• /
• 제19권5호
• /
• pp.259-267
• /
• 2003

A brake device for the high-speed impacting object is designed using an axial crushing of thin-walled metal cylinder. Thickness of the cylinder is increased smoothly from the impacting end to the fixed end, resulting in the truncated cone shape. Truncated cone shape minimizes the imperfection-sensitivity of the structure and ensures that plastic hinges are formed sequentially from impacting end. This prevents the undesirable sudden rise in the first peak-crushing load. Several specimens with different conic angles, mean thickness of the wall, and materials were designed and quasi-static compression tests were performed on them. Results indicate that adoption of appropriate conic angle prevents simultaneous wrinkles generation and sudden rise of crushing load and that appropriate conic angle differs in each case, depending on the geometry and material property of the cylinder. Finite element analysis was performed for static compression of the cylinder and its accuracy was checked for the future application.

• Journal of Korean Vacuum Science & Technology
• /
• 제3권1호
• /
• pp.24-29
• /
• 1999

The characteristic behaviors of CH3Br were examined first for the dry etching of polysilicon in a Cl2/CH3Br/O2 plasma. CH3Br is revealed one of the excellent additive gases to control anisotropy of etching profile and to give no undercutting for various typed of polysilicons. CH3Br acts as a passivation precursor on the side wall in etch cavity by forming polymer-like films such as CHxBry(x+y=1,2). The decrease of etch selectivity due to the reaction if the C-containing species from CH3Br with the surface O atoms of SiO2 was overcome by the addition of O2 into plasma, resulting that the selectivity increased by 2~3 times. According to the results of optical emission signals, CH3Br should be dissociated into several fragments to give more hydrogen atoms than bromine atoms in our helical resonator system.

• Journal of Pharmaceutical Investigation
• /
• 제18권4호
• /
• pp.187-195
• /
• 1988

Poorly permeable $Eudragit^{\circledR}$ RS 100 polymer was used as a wall material for the microencapsulation of zipeprol dihydrochloride by a phase separation method from chloroform-cyclohexane system with 5% polyisobutylene in cyclohexane, and microcapsules obtained were evaluated in vitro by particle size analysis, scanning electron microscopy, drug release test and in vivo bioavailability test in rats. The mechanism of drug release from microcapsules appeared to fit Higuchi matrix model kinetics. The area under the first moment of plasma concentration-time curve of the microcapsules obtained was considerably increased (p<0.05) as compared with that from zipeprol dihydrochloride oral solution. Therefore, it may be suggested that $Eudragit^{\cirledR}$ RS 100 coated zipeprol dihydrochloride microcapsules can be used as a sustained release medication.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계학술대회논문집
• /
• pp.381-384
• /
• 2005

The purpose of this study is to develop a prediction model for evaluating heavy-weight floor impact sounds in a test building. Three rooms in the test building (slab thickness In and 240mm), which consist of frame concrete structures were tested and modeled. First, the SPL distribution in the receiving room was analyzed by measuring SPL at 90 positions using a bang machine. Then, a vibration model using finite element method is proposed considering the material properties and boundary conditions. In addition, the result of transient analysis was compared with field measurements using a standard heavy-weight impact source. Through a vibro-acoustic simulation program, an acoustic model evaluating the building elements (reflected wall, nor, window and door) was proposed. Finally, validation of the prediction model was conducted by vibro-acoustic analysis with field measurements of noise radiation characteristics in receiving rooms.

• 한국실내디자인학회논문집
• /
• 제19권4호
• /
• pp.58-65
• /
• 2010

The purpose of this study is to be applied with the basic data for the design method in the housing space which is differential. So, we analyzed the expression method and the application characteristic to materials of units in housing complex. To that, we researched on the condition of finishing material about the kind of material, color, texture and pattern for components in living room space. The results of this study are as follows : First, at the present time, the Object concept is expressed by 'mixing' and 'juxtaposition' of material, texture and pattern of finishing materials in housing space. But, we could find that the Object concept was used restrictively in housing space. So, we have to find different expression methods to be the effective and differential design by being applied Object concept for the housing space. Second, the 'mixing' which is the method to express the Object concept is showed in only 'art wall'. so, we can estimate that the method is the limited method to plan the varied housing. It is needed various expression methods to design components for the housing space. Third, it showed that the 'mixing' was a passive expression method using a little differential for design of housing space. We could estimate that similar methods were applied to the housing design. By results of this study, we can think that the develop study is needed to find design methods for expression of the Object in housing space.

• 한국화재소방학회논문지
• /
• 제33권4호
• /
• pp.89-96
• /
• 2019

본 연구에서는 우선경보방식으로 경보음이 발생되는 경우 발화층과 직상층 이외의 다른 층으로도 전달되는 경보음에 대하여 건축음향 시뮬레이션을 활용하여 서로 다른 엘리베이터 배치를 갖는 3가지 조건에 대하여 예측하였다. 엘리베이터 샤프트에 흡음재가 설치되어 있지 않은 현재 조건으로 예측한 경우, 경보 발생층에서 멀어질수록 전달되는 경보음 크기는 작아졌지만, 3개층이 떨어진 경우에도 약 54 dB(A)~56 dB(A) 크기로 전달되어 일반적인 공동주택의 배경소음 보다 크게 전달되는 것으로 예측되었다. 이전 연구에서 개선안으로 제시된 엘리베이터 샤프트에 흡음재를 적용한 결과 인접층으로 전달되는 경보음 레벨은 약 12 dB~16 dB 정도 작아질 수 있는 것으로 예측되었다. 이는 공동주택의 배경소음 레벨과 유사하거나 작은 정도로 국가화재안전기준에서 규정한 일제경보방식의 의도대로 경보음이 발생되는 발화층과 직상층 이외의 층으로 전달되는 현상을 개선할 수 있을 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
• /
• 제47권1호
• /
• pp.21-32
• /
• 2019

In order to investigate the decay process of wood treated with preservative, waterproofing agent and their compound systems, a full-cell process was applied to impregnate the sapwood of poplar (Populus cathay) at paraffin wax emulsion concentrations of 0.5% and 2.0%, Copper Azole (CA) concentrations of 0.3% and 0.5%, and their four compound systems, respectively. Leaching tests and laboratory decay resistance against the white-rot fungus Corious versicolor (L.) Murrill for treated wood were carried out according to the America Standard E11-06 and China Standard GB/T 13942.1-2009. At certain time intervals during the decay test, samples were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction technique (XRD) to investigate the time-dependent changes of chemical components and crystalline structure, thus clarifying the decay mechanisms. The results suggested that white-rot fungi degrade hemicellulose and lignin in the wood cell wall first, followed by a simultaneous degradation of polysaccharides and lignin. Besides, CA could not only slower the decomposition of both hemicellulose and lignin, but also reduce the degradation amount of hemicellulose. However, paraffin wax emulsion at high concentration had a negative effect on the impregnation of CA for the compound system treated wood.

• 한국실내디자인학회논문집
• /
• 제18권6호
• /
• pp.104-114
• /
• 2009

The purpose of study was understanding necessity of environment design for underground parking lot in residential design plan and grasping design plans of 'Activity Support' that considerate women, exclude women's unsecured feeling at underground parking lot. The inquiry analyzed 6 design plan in design competition that considerate women according to precede studies, a theory of CPTED, a design guide for wayfinding, and survey. A ramp, circulation, entrance, lighting, ventilation, and space design plan are proceed on this study The result are as below. First, a rectilinear figure ramp suits entrance plan on the circulation, but if it is not possible, cross-using of rectilinear and curvilinear figure ramp plan is desirable. Second, on the circulation plan, vehicles circulation plan and equality parking distribution plan got accomplished generally, and help senses of direction because it is planed network systemize. On a large scale underground parking lot, simplify parking circulation to convenience entrance and exit for weak in sense of direction. Third, the shape and material that‘s environmentally conscious will be in use to the entrance plan. As the first stage to the underground, artwork that women prefer can modulate the rejection of underground space. Forth, natural lighting system and ventilation can make the environment-friendly space, decrease the women’s rejection to the underground, it can also keep a natural watch on the space. Fifth, on the space design plan, it can use bright and comfortable design of wall and ground to decrease the women‘s rejection, also it is useful to the sense of direction. LED indirect lighting plan that 58.7% of women prefers on survey reflects women’s state of desire that bright and atmosphere. In addition, proper use of plans that subsidiary facilities, rest area with Sunken, and nature-friendly material can minimize differences of underground and ground parking lot.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.658-663
• /
• 2011

The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

• 대한치과보철학회지
• /
• 제44권1호
• /
• pp.10-19
• /
• 2006

Statement of problem : The various kinds of properties of post and core may affect the stress distribution to the root of endodontically treated teeth Purpose: To evaluate the influence of various kinds of properties of post and core to the stress distribution to the root of endodontically treated teeth. Material and methods: Mandibular first premolar, prepared by general shape of post and core with gold crown, was used to two dimensional axisymmetric modeling for finite element analysis. Then property values of 8 different kinds of post and core was substituted for each. Finally, stress distribution shown areas around the root of post and core was analysed after applying 50N of vortical and oblique load. Results: 1. Stress value of oblique load was much higher than the maximum stress value of vertical load. 2. Under oblique load, very concentrated stress was located on post periapical area and variations in stress were very severe. Contrary to this, stress distribution was relatively uniform in vertical load. 3. Post materials with higher elastic modulus showed relatively more apically focused stress, and post materials with lower elastic modulus showed stress focused on cervical area on the axial wall of post. 4. Stress change according to the properties of core was shown only in the cervical area of post and below core as the higher elastic modulus, then increased in stress. 5. Post and core with medium value of elastic modulus showed relatively uniform stress distribution. Conclusions: Post materials with higher elastic modulus showed relatively more apically focused stress, and post materials with lower elastic modulus showed stress focused on cervical area on the axial wall of post. Stress change according to the properties of core was shown only in the cervical area of post and below core.