• 한국세라믹학회지
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• 제45권10호
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• pp.644-650
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• 2008

It has been proposed that the Cao-$SiO_2$ binary system can be good basic composition of bioactive glasses and glass-ceramics. In the present study, various kinds of Cao-$SiO_2$ gels were prepared by sol-gel method in order to control the microstructure which are related to their dissolution rate, induction period of apatite formation in body environment. Characterization of the gels were done by wet chemical analysis, SEM observation, FT-IR spectroscopy and XRD. The gelation time decreased with CaO content. However, the volume of all the dried gel decreased to 50% of the wet gels irrespective of increasement of CaO content. All the Cao-$SiO_2$ gels were amorphous and contained a large amount of silanol groups on their surfaces after heat treatment up to $800^{\circ}C$. The interconnected structure of the gel changed to agglomerated spherical powders when Ca content exceed to 20 mol%. Most of the Cao-$SiO_2$ gel showed amorphous when heat-treated up to $900^{\circ}C$. However, quartz and cristobalite was produced when heat-treated at $1000^{\circ}C$ and resultant microstructure of the gel contained microporous structure.

• Journal of the Korean Wood Science and Technology
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• 제39권6호
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• pp.498-504
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• 2011

The purpose of this study was to investigate and develop an eco-frendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The waste soybean oil (WSBO) was reacted with $O_3$ at the rate of $450m{\ell}$(acetone) : $50m{\ell}$ (WSBO) for different times, 1, 2, 3 hrs. The investigation of the modified chemical strecture of the ozonied WSBOs were conducted using FT-IR. As ozonification time increased, the peak of the unsaturated double bonds was disappeared especially ozonized-3hrs and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywood were made at $150^{\circ}C$ with 4 minutes hot-press time using the different ozonized 3 hrs WSBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased until 1 : 0.5~1 : 3, but it decreased 1 : 4, as the contents of pMDI increased. The results of the dry, wet and cyclic bond strengths the equivalent ratio was formed approximately between 1 : 2~1 : 3. And the 1 : 1~1 : 4 strengths met constantly the standard requirement of 7.0kgf/$cm^2$ (KS F3101). From the comprehensive view on the results of above experiment, it could be confirmed that ozonized WSBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• 한국세라믹학회지
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• 제46권6호
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• pp.574-582
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• 2009

$UO_2$ microsphere particles, core material of HTGR(High Temperature Gas Reactor) nuclear fuel, were prepared using by the GSP(Gel Supported Precipitation) method which is a modified-method of the wet sol-gel process. The spherical shape of initial liquid ADU droplets from the vibration nozzle system was continuously kept till the conversion to the final $UO_2$ microsphere. But the size of a final $UO_2$ microsphere was shrunken to about 25% of an initial ADU droplet size. Also, we found that the composition of dried-ADU gel particles was constituted of the very complicated phases, coexisted the U=O, C-H, N-H, N-O, and O-H functional groups by FT-IR. The important factors for obtain the no-crack $UO_2$ microsphere during the thermal treatment processes must perfectly wash out the remained-$NH_4NO_3$ within the ADU gel particle in washing process and the selections of an appropriate heating rate at a suitable gas atmosphere, during the calcining of ADU gel particles, the reducing of $UO_3$ particles, and the sintering of $UO_2$ particles, respectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.293-296
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• 2002

In this study, the object is a development on uroflowmetry system to detect a voiding symptom conveniently in home or hospital. The hardware was composed of mechanism and system circuit part, the software was divided into firmware and PC program part. The following experiment was performed to evaluate an ability of classification and fitness. First, the following parameters was calculated in each flow curve pattern. The parameters are MFR, AFR, VOL, VT, FT, and TMF. A significant difference among parameters was examined through a statistical analysis for extracted parameters between normal and abnormal group. In the next work, the following experimentation was performed to classify the voiding symptom. Analysis of congregate rate was examined to find out classification possibility about each symptom of BPH, voiding difficulty, detrusor failure and hyperreflexia, unstable bladder. The uroflow data with the above symptom was divided into normal and abnormal group using fuzzy classifier. and that was performed appending the other group again. Fuzzy classification result using MFR and AFR was superior by 89.6 % more than grouping evaluation including VOL.

• 한국식품영양과학회지
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• 제42권4호
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• pp.556-562
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• 2013

본 연구에서는 기존의 유기용매를 이용한 추출을 지양하고 환경 친화적이고 간단한 추출방법을 고안하여 톳의 다당류 성분(WSP-A)을 추출해내었고, WSP-A가 지질의 흡수에 미치는 효과를 알아보기 위하여 in vitro 상으로 lipase inhibition assay와 in vivo로 고지방 식이로 비만을 유도한 rat을 이용한 동물실험을 수행하였다. 그 결과 톳 유래 다당류는 alginate와 유사한 성분이지만 성분당 분석을 통하여 fucose가 주 당성분인 polysaccharide로 밝혀졌고, 이는 alginate보다 뛰어나고 안정한 lipase inhibitor로써 작용하였다. 또한 동물실험에서는 WSP-A를 포함하는 음용수로 제공한 것과 제공하지 않은 대조군은 무게 변화량에 유의적인 차이를 보일 뿐 아니라 비만 예방군과 비만 치료군 사이에서도 유의적인 차이를 나타내었다. 식이섬유를 이용한 연구와 비교해보았을 때, 톳 유래 다당류는 식이섬유 이상의 효과뿐만 아니라 뛰어난 lipase inhibitor로 체중감량을 나타내었고 이는 인간췌장유래 리파아제(human pancreatic lipase)의 저해활성과 더불어 인체 내에서의 작용 가능성을 짐작하고 있다. 따라서 톳 유래 다당류 성분은 식이성 섬유의 공급원 뿐만 아니라 추후에 효소활성 저해 효과에 대한 보다 명확한 작용기전을 밝혀낸다면 단순한 건강 기능성 식품 소재보다 lipase inhibitor로써 항비만 약물로 고부가가치를 창출해낼 수 있을 것으로 사료된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.425-425
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• 2011

The photocatalytic decomposition of toluene gas was investigated with $TiO_2$ on nano-diamond powder (NDP) under UV irradiation. Atomic layer deposition (ALD) was used for the growth of $TiO_2$ on the NDP. The structure and surface properties of catalysts were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The photocatalytic activity for the toluene decomposition was evaluated by measuring the concentration change of toluene and $CO_2$ gas with gas chromatography (GC)-flame ionization detector (FID) system. The photocatalytic activities of $TiO_2$/NDP catalysts were compared with that of P-25. The rate of initial photocatalytic decomposition of toluene for the $TiO_2$/NDP catalysts was relatively lower when compared to P-25. The photocatalytic activity of P-25 was rapidly decreased with time, whereas, the deactivation of $TiO_2$/NDP catalysts was less pronounced. Therefore, as the reaction time increased, the photocatalytic activity of $TiO_2$/NDP catalysts became higher than that of P-25. The intermediates such as benzaldehyde or benzoic acid, etc were more easily adhered to the active site on the P-25 surface during reaction, resulting in easier deactivation of P-25. These results could be confirmed using FT-IR spectroscopy. We suggest that the NDP used as substrate can reduce the deactivation of $TiO_2$ on the surface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.459-459
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• 2012

Recently, the discharge of global warming gases in dry etching process of TFT-LCD display industry is a serious issue because perfluorocarbon compound (PFC) gas causes global warming effects. PFCs including CF4, C2F6, C3F8, CHF3, NF3 and SF6 are widely used as etching and cleaning gases. In particular, the SF6 gas is chemically stable compounds. However, these gases have large global warming potential (GWP100 = 24,900) and lifetime (3,200). In this work, we chose C3F6O gas which has a very low GWP (GWP100 = <100) and lifetime (< 1) as a replacement gas. This study investigated the effects of the gas flow ratio of C3F6O/O2 and process pressure in dual-frequency capacitively coupled plasma (CCP) etcher on global warming effects. Also, we compared global warming effects of C3F6O gas with those of SF6 gas during dry etching of a patterned positive type photo-resist/silicon nitride/glass substrate. The etch rate measurements and emission of by-products were analyzed by scanning electron Microscopy (SEM; HITACI, S-3500H) and Fourier transform infrared spectroscopy (FT-IR; MIDAC, I2000), respectively. Calculation of MMTCE (million metric ton carbon equivalents) based on the emitted by-products were performed during etching by controlling various process parameters. The evaluation procedure and results will be discussed in detail.

• 한국식생활문화학회지
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• 제12권2호
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• pp.137-147
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• 1997

The purpose of this study was to determine the influences on physical status and study achievement by the dietary behavior of the youth in Korea. The survey was carried from June to July, 1995 by way of questionnaire to 397 students. The students' study achievement records and physical status were analyzed by the factor of dietary behavior. The results were as follows: 1 The average physical status of male students was lean, but females were standard. 76ft of mothers of the subjects were working in specialty farming. The monthly income of their family was $1000{\sim}1500$ thousand Won and students' pocket money was $20{\sim}40$ thousand Won per month. 2. The aspects of meal behavior included the general idea that the meal was thought to relieve hunger, and preference of taste was spiciness The most important factor of the meals for the students was taste. Their bad meal habits were quick eating and irregularity of meals. 3. There was a significant difference in the comparison of the study achieving records with the frequency of supper However, there was no one meaningful difference between study achievement records and the attendance rate to school, health status, and living conditions. However, there was a significant difference between their study records and eating with family. The students, who had the breakfast and/or supper with family, remarked better study records than other groups. 4. Also, there was a significant difference of study records with physical status. The overweight or obese students had a lower degree of study score (p<0.1). Adolescence is considered a period of setting up dietary behavior, so it is necessary to educate good nutrition and dietary habits for students to keep in healthy physical condition and with high study achievements.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.138-145
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• 2011

Diesel particulate filter (DPF) systems are being used to reduce the particulate matter emission of diesel vehicles. The DPF should be regenerated after certain driving hours or distance to eliminate soot in the filter. The most widely used method is active regeneration with oxygen at $550{\sim}650^{\circ}C$. Syngas (synthetic gas) can be used to lower the regeneration temperature of Catalyzed DPF (CDPF). The syngas is formed by fuel reforming process of CPOx (Catalytic Partial Oxidation) at specific engine condition (1500rpm, 2bar) using 1wt.% $Rh/CeO_2-ZrO_2$ catalyst. The oxidation characteristics of PM with syngas supplied to filter were studied using partial flow system that can control temperature and flow rate independently. The filter is coated with washcoat loading of $25g/ft^3$ $Pt/Al_2O_3-CeO_2$, and multi-channel CDPF (MC-CDPF) was used. The filter regeneration experiments were performed to investigate the effect of syngas exothermic reaction on soot oxidation in the filter. For this purpose, before oxidation experiment, PM was collected about 8g/L to the filter at engine condition of 1500rpm, bmep 8bar and flow temperature of $200^{\circ}C$ Various conditions of temperature and concentration of syngas were used for the tests. Regeneration of filter started at 2% $H_2$ and CO concentration respectively and inlet temperature of $260^{\circ}C$. Filter Regeneration occurs more actively as the syngas concentration becomes higher.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.76-82
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• 2014

1-Methylimidazole-2-thiol, as a kind of mercaptans, is a typical organic pollutant which has not been efficiently removed. In this study, titanium dioxide ($TiO_2$) photocatalyst based on magnetic multi-walled carbon nanotubes (MWCNTs) was synthesized via hydrothermal and sol-gel methods. The as-prepared photocatalyst was extensively characterized by X-ray diffraction (XRD), X-ray energy diffraction spectrum (EDS), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectra, UV-Vis diffuse reflectance spectra (UV-vis DRS) and vibrating sample magnetometer (VSM). This photocatalyst of $TiO_2$/$Fe_3O_4$/MWCNTs was proved to exhibit high photocatalytic efficiency and the photodegradation rate could reach nearly 82.7% for the degradation of 1-methylimidazole-2-thiol under ultraviolet irradiation. In addition, the results demonstrated that inorganic ions had a negative impact on photodegradation of 1-methylimidazole-2-thiol to varying degrees. Moreover, pH had a great and complex effect on photocatalytic degradation of 1-methylimidazole-2-thiol under ultraviolet irradiation.