• 한국정밀공학회지
• /
• 제29권8호
• /
• pp.879-886
• /
• 2012

The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.

• 한국지리정보학회지
• /
• 제8권4호
• /
• pp.114-122
• /
• 2005

본 연구의 목적은 오대산 국립공원을 대상으로 수치표고모텔, 용도지구 및 토지피복분류도를 작성하여 경관특성을 파악하고, 가시권분석을 통해 시각적 경관관리방안을 제시하는 것이었다. 분석결과, 용도지구는 자연환경지구의 면적이 감소하고 자연보존지구가 상대적으로 확대되어 보전의 성격이 강화된 반면, 취락지구도 면적이 증가하여 개발 가능성이 증가하였다. 토지피복은 자연환경지구에서 농경지 및 도시지역의 증가가 나타났다. 가시권분석을 통해 가시중복도가 높게 나타난 지역은 대부분 자연보존지구였으며 산림지역이 대부분을 차지하였다. 그러나 일부지역은 자연환경지구 내에 포함되어 지속적인 경관관리가 요구되었다.

• 한국환경보건학회지
• /
• 제20권3호
• /
• pp.85-95
• /
• 1994

This study was performed to find out the detoxication effects of natural products Thuja orientalis, leaf of acorn, aloe ferox mill, pine cone, pine root, lonicerae flos on nickel toxicity. The experimental rats were divided into 3 groups such as nickel alone treatment group, natural products treatment groups before and after nickel treatments. Each group was administered with difference dose of nickel such as 6.6 mg/kg/day, 13.2 mg/kg/day, 19.8 mg/kg/day respectively, for 14 days. Natural products were administered by 400 mg per kilogram body weight rat per day. The weight change of rats, nickel concentration in organs, survival rate of rats, morphology of organs were observed in the experimental groups. The results obtained by the experiment were as follows: 1. The rats in the group treated with natural products had no effect on the weight gain. 2. The mean survival rate of rats in the nickel alone treatment group was 72.5% (6.6 mg/kg/day), 68.9% (13.2 mg/kg/day), 60.2% (19.8 mg/kg/day) respectively. 3. As for the amount of nickel accumulation in organs, it was the lowest amount treated with pine cone, pine root in that order. 4. When kidney and liver tissues were observed with as optical microscope, obvious change were visible in those tissues treated groups with Lonicerae and Aloe.

• Bulletin of the Korean Chemical Society
• /
• 제35권3호
• /
• pp.925-928
• /
• 2014

A dye-sensitized solar cell (DSSC) was fabricated with a nanocrystalline $TiO_2$ film electrode on FTO glass, N719 dye, electrolytes (or $CsSnI_3$), and counter Pt electrode by incorporating it with single-walled carbon nanotubes (SWNTs). SWNTs were combined with $TiO_2$ film, $CsSnI_3$, Pt electrode, separately, and the SWNT-containing cell was compared with a pristine cell in cell performance. We also examined the performance change by pressing $TiO_2$ film, during cell fabrication, inside a high pressure chamber. Mostly, the change of conversion efficiency was compared for each cell, and an atomic force microscopy data were suggested to explain our results.

• Computers and Concrete
• /
• 제26권1호
• /
• pp.31-52
• /
• 2020

This paper investigates the size dependent effect on the vibration analysis of a porous nanocomposite viscoelastic plate reinforced by functionally graded-single walled carbon nanotubes (FG-SWCNTs) by considering nonlocal strain gradient theory. Therefore, using energy method and Hamilton's principle, the equations of motion are derived. In this article, the effects of nonlocal parameter, aspect ratio, strain gradient parameter, volume fraction of carbon nanotubes (CNTs), damping coefficient, porosity coefficient, and temperature change on the natural frequency are perused. The innovation of this paper is to compare the effectiveness of each mentioned parameters individually on the free vibrations of this plate and to represent the appropriate value for each parameter to achieve an ideal nanocomposite plate that minimizes vibration. The results are verified with those referenced in the paper. The results illustrate that the effect of damping coefficient on the increase of natural frequency is significantly higher than the other parameters effect, and the effects of the strain gradient parameter and nonlocal parameter on the natural frequency increase are less than damping coefficient effect, respectively. Furthermore, the results indicate that the natural frequency decreases with a rise in the nonlocal parameter, aspect ratio and temperature change. Also, the natural frequency increases with a rise in the strain gradient parameter and CNTs volume fraction. This study can be used for optimizing the industrial and medical designs, such as automotive industry, aerospace engineering and water purification system, by considering ideal properties for the nanocomposite plate.

• Nuclear Engineering and Technology
• /
• 제55권5호
• /
• pp.1821-1829
• /
• 2023

The temperature distribution of the reactor pool under natural circulation induced by the RVACS operation was experimentally studied. According to the Bo' based similarity law, which could reproduce the temperature distribution of the working fluid under natural circulation, SINCRO-2D facility was designed based on the PGSFR. It was reduced to 1 : 25 in length scale, having water as a simulant of the sodium, which is the original working fluid. In general, temperature was stratified, however, effect of the natural circulation flow could be observed by the entrainment of the stratified temperature. Relative cooling contribution of the upper plenum (narrow gap) and lower plenum was approximately 0.2 and 0.8, respectively. In the range of decay heat from 0.2% to 1.0%, only the magnitude of the temperature was changed, while the normalized temperature maintained. Boundary temperature distribution change made a global temperature offset of the pool, without a significant local change. Therefore, the decay heat and cooling boundary condition had no significant effect on temperature distribution characteristics of the pool within the given range of the decay heat and boundary temperature distribution.

• 한국패션뷰티학회지
• /
• 제4권2호
• /
• pp.31-41
• /
• 2006

As chemistry dyes has considerably developed with industrial society, natural dyeing has gone out of people's head for a long time. But the serious problems from environmental pollutions and ecological damages make people look far Well-being. Natural dyeing also has concentrated again and the interests about it are growing larger and larger. Well-being that a modern person pursues and a Natural dyeing walk along a same string of connection. That is, people want their life to change from quantity matters into qualities. The relations of the natural dying which has the color of nature and Well-being phenomenons are analyzed through dissertations and references. The study about the correlations between natural dying and well-being shows that many advantages of natural dyestuff and the effects of dyestuff are definitely needed to people living in modern times. Also for the protection of an ecosystem, rapid popularization and the development of new design is completely required.

• 환경생물
• /
• 제29권4호
• /
• pp.345-352
• /
• 2011

내설악 전나무 자연림 임분구조를 좀 더 체계적으로 이해하기 위하여 종다양성 추정에 사용되는 Shannon-Weaver-Index를 응용한 Herles의 구조표현인자 다양성 계산 방법을 도입하여 12개의 임분을 조사하였다. 임분 구조 변화는 당연히 phase의 변화에 종속되지만 개개인자들 간의 연관에서 자연림의 특성이 재확인되었다. 우선 내설악 전나무 자연림의 구조는 표현인자 다양성의 결과에서 보이는 것처럼 다양성이 상대적으로 낮은 것으로 나타났다. 인자 간의 상관에서 종다양성은 구조 변화 관련 전체 인자 (다양성)와 미약한 관계만 보이며, 어느 정도 설명이 가능한 연관을 보이는 것으로는 개체수였으며, 개체수가 증가할수록 임분구조 전체의 다양성은 떨어지는 결과를 보인다. 입목축적이나 고사목 축적은 대부분 조사구에서 천연갱신고도와 연관을 보이며 다른 인자와는 별다른 관계를 보이지 않는 것으로 나타났다. 타 구조표현인자 서로서로의 연관은 천연갱신고도와 관련하여 울폐도나 수관면적, 형태 등과 연관을 보였으며 수고나 흉고직경은 타 인자들과 별다른 연관을 보이지 않았다. 전체적으로 내설악 전나무림 구조변화 이해에 도움을 주는 결과를 가져왔지만 좀 더 많은 조사구에 대한 조사가 필요하리라 본다.

• Journal of Microbiology
• /
• 제38권4호
• /
• pp.265-269
• /
• 2000

Iron increased the susceptibilities of clinical isolates Pseudomonas aeruginosa to quinolones. In the presence of iron, increased susceptibilities to ofloxacin were observed in twenty-six out of thirty isolates and with no change in four isolates. In the case of norfloxacin, iran increased susceptibilities of twelve isolates but did not render any change in eighteen isolates. In the case of ciprofloxacin, iron decreased the MICs (Minimal Inhibitory Concentration) of twenty isolates, increased the MIC of one isolate, and did net change the MICs of nine isolates. To find out how iron increased susceptibility to ofloxacin, bacterial cells were grown in Muller Hinton (MH) media and succinate minimal media (SMM) to induce iran acquisition systems and the intracellular ofloxacin concentrations were assayed in the presence of iron. The addition of iron to the media decreased the MICs of cells whether they were grown in MH or SMM. Siderophores, carbonyl cyanide m-chlorophenylhydrazone (an inhibiter of proton motive force), and ouabain (an inhibitor of ATPase) did not decrease the effect of iron. Results suggested that the increase in the intracellular ofloxacin concentration by iron is accomplished not by decreasing the efflux but by increasing the of ofloxacin permeability.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제18권1호
• /
• pp.1-5
• /
• 2013

Global climate changes affect the local hydrologic cycle, and subsequently, require changes in water resource management strategies of Korea. Variations in precipitation and urbanization have adverse effects on the reasonable and efficient utilization of groundwater resources. Groundwater management strategies of Korea have been implemented based on the evaluation of "sustainable yield", which is calculated from the amount of annual recharge. However, this sustainable yield has no consideration of natural discharge and dynamic equilibrium of the groundwater system. Therefore, for the effective groundwater management strategies of the following decades, we need representative and reliable observations, and have to develop methods for the systematic analysis and interpretations of the data to draw valid information in linkage of natural and societal environmental changes.