• 한국안전학회지
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• 제24권2호
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• pp.7-12
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• 2009

The machining process of ceramics can be characterized by cracking and brittle fracture. In the machining of ceramics, edge chipping and crack propagation are the principal reasons to cause surface integrity deterioration. Such phenomenon can cause not only poor dimensional and geometric accuracy, but also possible failure of the ceramic parts. Thus, traditional ceramics are very difficult-to-cut materials. Generally, ceramics are machined using conventional method such as grinding and polishing. However these processes are generally costly and have low MRR(material removal rate). To overcome such problems, in this paper, h-BN powder, which gives good cutting property, is added for the fabrication of machinable ceramics by volume of 10 and 15%. The purpose of this study is an analysis of endmill's rake angle for appropriate tools design and manufacturing for the machinable ceramics. In this study, Experimental works are executed to measure cutting force, surface roughness, tool fracture, on different axial rake angle of endmills. Cutting parameters, namely, feed, cutting speed and depth of cut are used to accomplish purpose of this paper. Required experiments are performed, and the results are investigated.

• 펄프종이기술
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• 제40권4호
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• pp.27-33
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• 2008

Polyethylene terephtahalate has been used in several areas such as fiber, film, bottle, and disposable products. Production of PET has been rapidly increasing these days. Since PET is a semi-permanent material, it has a non-biodegradable character in itself. Wasted PET products can cause serious environmental problems. Many countries around the world impose environmental legal restrictions over their abandonments. Many researches on the enviromental influence factors and treatment techniques of the wasted PET have been carried out. The main objective of this study is to develop a new sizing agent using recycling PET and improve its internal sizing effect. Dried powder of PET was used to make the modified PET. After extracting water-dispersible PET by subcritical hydrolysis, polyester resins have been extracted and triphenyl phosphate(TPP) has been added to obtain optimal internal sizing agent. It was found that the optimum dosage of TPP was 2% (per PET weight) and the hydrolysis temperature was independent on making the modified PET.

• 한국연소학회지
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• 제14권4호
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• pp.25-32
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• 2009

In commercial combustion systems, heavy oil is one of main hydrocarbon fuel because of its economical efficiency. Regarding heavy oil combustion, due to increasing concerns over environmental pollutants such as carbon monoxide, unburned hydrocarbon and nitrogen oxides, development of low pollutant emission methods has become an imminent issue for practical application to numerous combustion devices. Also a great amount of effort has been tried to developed effective methods for practical using of biomass. It is also an important issue to reduce carbon tax. In this paper, an experimental study has been conducted to evaluate the effect of biomass reburning on NOx formation in a heavy oil flamed combustion furnace. Experiments were performed in flames stabilized by a multi-staged burner, which was mounted at the front of the furnace. Experimental tests were conducted using air-carried rice husk powder and LNG as the reburn fuel and heavy oil as the main fuel. The paper reports data on flue gas emissions and temperature distribution in the furnace for several kinds of experimental conditions. NOx concentration in the exhaust has decreased considerably due to effect of reburning. The maximum NOx reduction rate was 62% when the rice husk was used by reburn fuel, however it was 59% when the LNG was used by reburn fuel. The result shows the positive possibility of biomass reburning system for optimal NOx reduction.

• 동굴
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• 제79호
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• pp.77-81
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• 2007

In this paper deals with behavior of the magnetic abrasive using Sr-Ferrite on polishing charateristiccs in a internal finishing of staninless steel pipe a tying magnetic abrasive polishing. The magnetic polishing is the useful method to finish some machinery fabrications by using magnetic power. This method is one of the precision techniques and has in aim for clean technology in the transportation of the pure gas in the clean pipes. The magnetic abrasive polishing method is not so common in the field of machine that it is not known to widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper we deals with the development of the magnetic abrasive with the use of Sr-Ferrite. In this development, abrasive grain SiC has been made by using the resin bond fabricated at low temperature. And magnetic abrasive powder was fabricated from the Sr-Ferrite which was crushed into 200 mesh. The XRD analysis result shows that only SiC abrasive and Sr-Ferrite crystal peaks were detected, explaining that resin bond was not any more to contribute chemical reaction. From MACRO analysis, we found that SiC abrasive and Sr-Ferrite were strongly bonding with each other.

• Applied Biological Chemistry
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• 제11권
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• pp.101-104
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• 1969

Partition chromatography의 방법(方法)으로는 우선 cellulose powder colume을 시도해 보았으나 이는 얻어진 fraction의 용매제거의 난점(難點)이 있으므로 결국(結局) paper chromatography 방법(方法)만을 사용(使用)하였다. 연구결과(硏究結果)로는 우선 갈색색소의 fraction에 있어서 발효초기(醱酵初期)에 약간의 활성(活性)을 관찰(觀察)할수 있었으며 glycine이 함유된 fraction 에서는 발효초기에 벌써 상당한 활성을 보였으며 이는 또한 발효의 진행(進行)에 따라 점차 증가되었다. 그리고 N-glycoside의 fraction에서는 발효초기에 미약(微弱)한 활성(活性)을 관찰할 수 있었다. 그러나 paper chromatography의 방법(方法)은 본실험(本實驗)에 적합하지 않다고 생각되며 그 이유(理由)는 일회(一回)에 fractionation 할수있는 시료(試料)의 양(量)이 극(極)히 제한되어 있다는 점(點)과 또 fractionation 도중에 타물질(他物質)의 오염으로 인(因)해서 시료(試料)의 정확(正確)한 발효 활성(活性)을 측정(測定)할수 없다는 것이다.

• 마이크로전자및패키징학회지
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• 제25권4호
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• pp.9-15
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• 2018

This paper shows the principles and characteristics of the transient liquid phase (TLP) bonding technology for power modules packaging. The power module is semiconductor parts that change and manage power entering electronic devices, and demand is increasing due to the advent of the fourth industrial revolution. Higher operation temperatures and increasing current density are important for the performance of power modules. Conventional power modules using Si chip have reached the limit of theoretical performance development. In addition, their efficiency is reduced at high temperature because of the low properties of Si. Therefore, Si is changed to silicon carbide (SiC) and gallium nitride (GaN). Various methods of bonding have been studied, like Ag sintering and Sn-Au solder, to keep up with the development of chips, one of which is TLP bonding. TLP bonding has the advantages in price and junction temperature over other technologies. In this paper, TLP bonding using various materials and methods is introduced. In addition, new TLP technologies that are combined with other technologies such as metal powder mixing and ultrasonic technology are also reviewed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.324-327
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• 2005

An electrophoretic display using $TiO_2$ particles is the most promising candidate because it offers various advantages such as ink-on-paper appearance, good contrast ratio, wide viewing angle, image stability in the off-state and extremely low power consumption. The core technology of electrophoretic display is the dispersion controlling of $TiO_2$ nano particles in nonaqueous solution. To prepare an ink for electronic paper using electrophoretic properties of $TiO_2$ nano particles, cyclohexane with low dielectric constant and transparency, polyethylene for producing polymer coating layer which reduces apparent gravity of $TiO_2$, and $TiO_2$ powders were mixed together by planetary-mill. The zeta-potential value of $TiO_2$ particles in cyclohexane was measured about -40mV, but was measured over -110mV by dispersant attached to polyethylene-coated $TiO_2$ surface. Prepared electronic ink was filled in cross patterned micro-wall with $200{\mu}m$ in width and $40{\mu}m$ in height on ITO glass designed by photolithography. The response time of electronic paper evaluated by mobility of $TiO_2$ particle between micro-walls was measured 0.067sec, but the drift velocity from reflectance wave form during reverse from of electronic ink was measured 0.07cm/sec.

• Journal of the Korean Wood Science and Technology
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• 제52권2호
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• pp.134-144
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• 2024

This study aimed to analyze the anti-termite properties of tamanu (Calophyllum inophyllum L.) stem bark extracts against subterranean termites, specifically, Coptotermes curvignathus. The bark powder of C. inophyllum was extracted using different solvents, such as n-hexane, ethyl acetate, and methanol, using the maceration method. Anti-termite testing was performed using two paper disc methods: no- and two-choice tests. Whatman test paper was dripped with the extract solutions at concentrations of 4%, 6%, 8%, and 10% (w/v). Subsequently, the treated paper disc was placed into an acrylic tube, and the subterranean termite was added. The parameters utilized in the test included termite mortality and the weight loss of the test paper. The results revealed that the total extract yield of C. inophyllum stem bark was 30.24%. Furthermore, the extractive substances from C. inophyllum bark exhibited anti-termite activity. The most favorable outcomes were obtained with the n-hexane and ethyl acetate extracts at a concentration of 10%. The termite mortality and weight loss of the test paper were respectively 66% and 5.67% for the n-hexane extract and 66.67% and 6.19% for the ethyl acetate extract. In addition, the n-hexane extract contained friedelan-3-one, while the ethyl acetate extract contained 1,2-benzene dicarboxylic acid, dinonyl ester, and friedelan-3-one. The results suggested that these compounds are responsible for the observed anti-termite activity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.63-64
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• 2008

Electrokinetic motion of fullerene ($C_{60}$) particles in liquid crystal (LC) medium under an in-plane electric field has been studied for the application to the electronic paper display. Fullerenes move in the direction of applied electric field due to interaction between the induced dipole moment on $C_{60}$ and external electric field at lower threshold voltages compared to other devices such as QR-LPD (Quick Response Liquid Powder Display) and TBD (Twisting Ball Display). We also confirmed the bistability of fullerene particles in LC medium and the results showed that the 87% and 81% of original reflectance or transmittance of image was retained after 24 hours and 48 hours respectively. Our studies show the possibility that fullerenes can be used for electronic paper display.

• 한국응용곤충학회지
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• 제7권
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• pp.61-64
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• 1969

배나무 적성병균의 병자각세대에 분필하는 병자적 성분중 free sugar를 중심으로 기생엽중의 free sugar와의 상관관계를 생화학적으로 연구 고찰하여 아래와 같은 결과를 얻었다. 1. 병자각세대에 분필하는 병자적 성분중 free sugar를 paper chrmarography로 분석한 결과 fructose만이 확인되었다. 2. 기주 향나무 엽중의 free sugar는 galactose와 glucose 및 미지물질 2종임을 확인하였다. 3. 기주 배나무엽중의 free sugar로는 glucose, fructose 및 galactose를 확인하였다. 4. 배나무엽중의 arbutin-을 결정화하고 그 구조를 일반적인 방법과 paper chromatography로 분석하여 glucose와 hydroquinone의 결합체임을 확인하였다. 5. 0.05M arbutin 용액에 Emulsin을 조제하여 배양한 결과 분해 생성물로서 glucose를 확인하였고 이들 Emulsin은 모두 $\beta-glycosidase$를 함유하고 있음이 확정되었다. 이상 결과에서 보는 바와같이 병자적중의 fructose는 배나무 엽중에 있는 free sugar 및 glycoside인 arbutin이 Emulsin에 의하여 분해되어 glucose로 변화된 다음 균체내의 isomerase에 의하여 isomerization된 것이라 추측된다.