• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.403-414
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• 2001

The purpose of this study was to evaluate treatment effects of the modified Teuscher appliance (MTA) in early Class II division 1 malocclusion. For this purpose, treatment effects of the bionator were compared with those of the MTA. The twenty subjects who were treated excellently with bionator and MTA were selected in each group. In pre- and post-treatment lateral cephalograms, 50 variables were measured, and then the differences between pretreatment and posttreatment data of the bionator and the MTA were statistically evaluated by t-test. The results were as follows : 1. The linear measurements that showed large difference between the bionator group and the MTA group are U1 to FH, U1 to PP, U6 to FH, U6 to PP, Ar-Pog, ramus height, L1 to A-Pog, L1 to facial plane (p<0.05). 2. The angular measurements that showed large difference between the bionator group and the MTA group are SNB, SNA, FABA, APDI (p<0.05). 3. The measurements of the growth pattern such as facial height ratio, FMA, SN-MP angle showed no difference between two groups (p>0.05). These results suggest that the bionator influence the mandiblar growth and lower dentoalveolar structures more than the MTA, and the MTA influence upper jaw and upper dentoalveolar structures more than the bionator comparatively in early Class II division I malocclusion.

• The Korean Journal of Mycology
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• v.24 no.3 s.78
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• pp.237-242
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• 1996

Two depsides, medicinal herb products isolated from the methanol extract of Umbilicaria esculenta, inhibited human synovial fluid Phospholipase $A_2\;(PLA_2)$ ($IC_{50}$ of 0.22 and 0.26 mM, respectively). In the course of screening for antiinflammatory compounds from natural products, we successfully isolated two depsides $PLA_2$ inhibitory compounds, Orcinol and methyl orsellinic acid. The compounds were identified as orcinol and methyl orsellinic acid on the basis of various NMR studies including $^1H,\;^{13}C$ and DEPT experiments.

• The Korean Journal of Nuclear Medicine
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• v.35 no.1
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• pp.69-74
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• 2001

Purpose: $^{99m}Tc$-HMPAO is a radiopharmaceutical for imaging cerebral blood flow. HMPAO (RR, SS)-4.8-diaza-3,6,6,9-tetramethylundecan-2,10- dione bisoxime) has three stereoismers such as, meso-. d-, and l-HMPAO. Techentium complexes of meso-HMPAO and d,l-HMPAO are known to have different in vivo brain uptakes. In this study, enantiomers of HMPAO (d-HMPAO and l-HMPAO) were separated from d,l-HMPAO. These enantiomers were labeled with $^{99m}Tc$ and the biodistribution studies were performed in mice. Materials and Methods: An intermediate imine product was produced from 2,3-butanedione monooxime and 2,2-dimethyl-1,3-propanediamine (54% yield) and was reduced into a mixture of three isomers (35% yield). The meso-isomer was separated from d,l-mixture by repeated fractional crystallization (11 % yield). The d- and l-enantiomers were subsequently separated by co-crystallization with optical isomers of tartaric acid (25% and 5% yield. respectively). Each enantiomeric HMPAO was labeled with $^{99m}Tc$ by reacting with $SnCI_2{\cdot}2H_2O\;and\;^{99m}Tc$-pertechnetate. Biodistribution study was performed 1 hr after tail vein injection to ICR mice. Results: Radiochemical purities of each compound were over 80%. In biodistribution study. the brain uptakes of d,l- d- and l-form were 1.34, 1.12 and 1.67% ID/g, respectively. In case of l-lsomer the brain uptake was higher (1.5 fold) than d-isomer. Conclusion: We successfully purified each enantiomeric HMPAO. In biodistribution study of stereoismers of $^{99m}Tc$-HMPAO in mice, l-HMPAO may show better brain image than d,l-HMPAO which was supplied in a commercial kit.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.130-133
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• 1999

In this work, a capacitance-type alcohol gas sensor using porous silicon layer is developed to apply for breath alcohol measurement and its characteristics are estimated at room temperature. Current alcohol sensors using metal oxides such as tin-oxide are not only difficult to measure low alcohol concentration, but also should heat at $200\;to\;400^{\circ}C$ to improve the sensitivity. But the sensor using porous silicon layer has good sensitivity even at room temperature by very large effective surface area and suitable structure to fabricate integrated micro sensors. In the experiment, the capacitance was measured for the range of 0 to $0.5\%$ alcohol concentration with the interval of $0.05\%$, in which alcohol solution was kept at 25, 36, and $45^{\circ}C$ by a heater. As the result, good linearity was observed and the capacitance increased about 1.1, 2.6 and $4.6\%$ per the increment of $0.1\%$ alcohol concentration each temperature, respectively, at the frequency of 120 Hz.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.129-129
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• 2017

열전재료는 열에너지를 전기에너지로 또는 전기에너지를 열에너지로 직접 변환하는데 가장 널리 사용되는 재료이다. $Bi_2Te_3$계 열전 재료는 400K 이하의 비교적 저온 영역에서 높은 성능지수(Dimensionless Figure of merit, ZT($={\alpha}2{\sigma}T/{\kappa}$, ${\alpha}$: 제백계수, ${\sigma}$: 전기전도도, T: 절대온도, ${\kappa}$: 열전도도))를 나타내는 열전재료이며 자동차 시트나 정수기 등에 응용되고 있다. 열전모듈은 제조시 수십 개에서 수백 개 이상의 n형 및 p형 열전소자를 알루미나($Al_2O_3$)와 같은 세라믹 기판(substrate) 상에 접합된 동 전극 위에 전기적으로 서로 직렬로 접합시켜 제조한다. 기존의 열전모듈의 제조방법에는 동 전극 위에 위에 Sn합금 분말과 플럭스(flux)의 혼합물인 솔더페이스트를 스크린 인쇄법을 사용하여 동 전극에 도포한 다음, 그 위에 열전소자를 얹고 약 520K의 열풍을 가하여 솔더를 용융시켜 열전소자와 동 전극을 접합시킨다. 스크린 인쇄법에서는 인쇄 압력이 일정하지 않으면, 솔더페이스트 층의 두께가 균일하지 않게 되어 열전소자 접합부의 불량을 유발시킨다. 그러나 열모듈은 단 하나의 접합 불량이 모듈 전체의 열전변환성능에 심각한 영향을 줄 수 있기 때문에 본 연구에서는 이러한 문제점을 해결하기 위해, 솔더페이스트를 도포하지 않고 열전소자를 직접 동 전극과 접합할 수 있는 방법을 고안하였다. 무전해도금을 이용한 니켈층을 형성시킨 $Bi_2Te_3$계 열전소자 표면에 약 $50{\mu}m$의 주석도금층을 전기도금법을 구사하여 형성시켰다. 그 후, wire cutting을 통하여 $3mm{\times}3mm{\times}3mm$의 크기로 절단한 주석도금된 열전소자를 동 전극에 얹고 1.1KPa의 압력을 가하면서 523K의 핫플레이트 위에서 3분간 방치하여 직접(direct) 열압착 접합을 실시하였다. 접합부의 단면을 SEM을 이용하여 관찰한 결과, 동 전극과 열전소자 사이의 계면에 용융 후 응고된 주석층이 결함없이 균일하게 형성된 양호한 접합부를 관찰할 수 있었다. 따라서, 솔더페이스트를 이용하지 않고, 열전소자 표면에 주석도금을 실시한 후, 동 전극과 직접 열압착 본딩을 실시하는 방법은 균일한 접합계면을 얻을 수 있는 새로운 공정으로 기대된다.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.3_4
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• pp.464-472
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• 2002

The aim of this study was to elucidate dyeability and antimicrobial activity of cotton fabrics dyed with Sophora Radix extracts according to various mordants. Dyes were extracted from Sophora Radix using ethanol. Then, cotton fabrics were dyed with extracts two times by post-mordanting method in which the extract was 60% (owf, the mordant was 3% (owf), L.R was 1:20, the temperature was 60~7$0^{\circ}C$, the time of dyeing was 60min., and the time of mordanting was 60min.. The dyeability was evaluated by surface color and color fastness. The skin microorganism was evaluated on S. sureus, B. subtilis, S. epidermidis, P. acnes, P. aeruginosa, E. coli, A. niger, C. albicans and T. mentagrophytes. The results are as follows; 1. When mordants were treated, surface color was 3.3Y to 0.1 GY in H (hue) value which indicated greenish yellow to yellow 2. The color fastness to perspiration, dry-cleaning, rubbing, and washing stain fabric showed 4~5 degree. The color fastness to light was improved to 4 degree by treatment of mordants. The color fastness to washing was 2 degree which was somewhat poor. 3. Cotton dyed with ethanol extracts was excellent on S. aureus, B. subtilis, S. epidermidis and p. antis. But that showed poor antibacterial activities on P. aeruginosa and E. coli such as gram negative baterials 4. Antibacterial activity of cotton fabrics dyed didn't be improved by treatment of mordant 5. Antifungal activity of cotton dyed with ethanol extracts was excellent on T. mentagrophytes. Especially, on T. mentagrophytes there was no growth of fungus during 72 hours in cotton dyed mordanting with SnCl$_2$.$_2$$H_2O$.

• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.101-106
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• 1983

It was the purpose of this study to investigate the fracture mode of dental amalgam by observing the crack propagation, and to relate this to the microstructure of the amalgam. Caulk 20th Century Regular, Caulk Spherical, Dispersalloy, and Tytin amalgam alloys were used for this study. After each amalgam alloy and Hg measured exactly by the balance was triturated by the mechanical amalgamator (Capmaster, S.S. White), the triturated mass was inserted into the cylindrical metal mold which was 4 mm in diameter and 12 mm in height and was pressed by the Instron Universal Testing Machine at the speed of 1mm/min with 120Kg. The specimen removed from the mold was stored in the room temperature for a week. This specimen was polished with the emery papers from #100 to #200 and finally on the polishing cloth with 0.06${\mu}Al_2O_3$ powder suspended in water. The specimen was placed on the Instron testing machine in the method similar to the diametral tensile test and loaded at the crosshead speed of 0.05mm/min. The load was stopped short of fracture. The cracks on the polished surface of specimen was examined with scanning electron microscope (JSM-35) and analyzed by EPMA (Electron probe microanalyzer). The following results were obtained. 1. In low copper lathe-cut amalgam, the crack went through the voids and ${\gamma}_2$ phase, through the ${\gamma}_1$ phase around the ${\gamma}$ particles. 2. In low copper spherical amalgam, it was observed that the crack passed through the ${\gamma}_2$ and ${\gamma}_1$ phase, and through the boundary between the ${\gamma}_1$ and ${\gamma}$ phase. 3. In high copper dispersant (Dispersalloy) amalgam, the crack was found to propagate at the interface between the ${\gamma}_1$ matrix and reaction ring around the dispersant (Ag-Cu) particles, and to pass through the Ag-Sn particles. 4. In high copper single composition (Tytin) amalgam, the crack went through the ${\gamma}_1$ matrix between ${\eta}$ crystals, and through the unreacted alloy particle (core).

• Journal of the Korean institute of surface engineering
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• v.39 no.5
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• pp.206-209
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• 2006

Indium tin oxide (ITO) films were synthesized on polymer (PES, polyethersulfone) at room temperature by pulsed DC magnetron sputtering. By the control of introducing hydrogen to argon atmosphere, the resistivity of ITO films was obtained at $5.27\;{\times}\;10^{-4}\;{\Omega}{\cdot}cm$ without substrate heating in comparison with $2.65\;{\times}\;10{-3}\;{\Omega}{\cdot}cm$ under hydrogen free condition. ITO film synthesized at Ar condition was changed from amorphous to crystalline. These result from the enhancement of electron temperature in $Ar\;+\;H_2$ plasma, which induces the increase of ionization of target materials and argon. The dominant increase of ions such as In II and O II and neutral Sn I was monitored by optical emission spectroscopy (OES). Thermal energy required for the crystalline film formation is compensated by kinetic energy transfer through ion bombardments to substrate.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.411-419
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• 1996

The Janggun magnetite deposits occur as the lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. The K-Ar age of alteration sericite indicates that the mineralization took place during late Cretaceous age (107 to 70 Ma). The ore deposition is divided into two stages as a early skarn and late hydrothermal stage. Mineralogy of skara stage (107 Ma) consists of iron oxide, base-metal sulfides, Mg-Fe carbonates and some Mg- and Ca-skarn minerals, and those of the hydrothermal stage (70 Ma) is deposited base-metal sulfides, some Sb- and Sn-sulfosalts, and native bismuth. Based on mineral assemblages, chemical compositions and thermodynamic considerations, the formation temperature, $-logfs_2$, $-logfo_2$ and pH of ore fluids progressively decreased and/or increased with time from skarn stage (433 to $345^{\circ}C$, 8.8 to 9.9 atm, 29.4 to 31.6 atm, and 6.1 to 7.2) to hydrothermal stage (245 to $315^{\circ}C$, 11.2 to 12.3 atm, 33.6 to 35.4 atm, and 7.3 to 7.8). The ${\delta}^{34}S$ values of sulfides have a wide range between 3.2 to 11.6‰. The calculated ${\delta}^{34}S_{H_2S}$ values of ore fluids are relatively homo-geneous as 2.9 to 5.4‰ (skam stage) and 8.7 to 13.5‰ (hydrothermal stage), which are a deep-seated igneous source of sulfur indicates progressive increasing due to the mixing of oxidized sedimentary sulfur with increasing paragenetic time. The ${\delta}^{13}C$ values of carbonates in ores range from -4.6 to -2.5‰. Oxygen and hydrogen isotope data revealed that the ${\delta}^{38}O_{H_2O}$ and ${\delta}D$ values of ore fluids decreased gradually with time from 14.7 to 1.8‰ and -85 to -73‰ (skarn stage), and from 11.1 to -0.2‰ and -87 to -80‰ (hydrothermal stage), respectively. This indicates that magmatic water was dominant during the early skarn mineralization but was progressively replaced by meteoric water during the later hydrothermal replacement.

• Clean Technology
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• v.26 no.3
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• pp.211-220
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• 2020

This experimental study investigates the design parameters to achieve ultra low NOx combustion of coal using a 80 kW capacity single-burner furnace. The influence of key design parameters such as SN, overall and burner-zone equivalence ratios, primary/secondary air ratio, overfire air (OFA) ratio were tested for a total of 81 cases. The results showed that weak swirl intensity of the burner leads to higher NOx emission whereas strong swirl intensity accompanies increased CO concentration desipte lower NOx emission. Therefore, finding an appropirate swirl intensity is essential for the burner design. Larger flow rate of secondary air increased NOx emission, whereas smaller flow rate stretches the flame and increased CO emission. The lowest NOx emission of 82 ppm (6% O₂) was achieved at the optimal condition of the present burner deisgn. It is expected to furrther lower the NOx emission by introducing splitting the burner secondary air into three or four streams.