• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.720-723
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• 2003

Electric stimulation of teeth is used for assessing pulp vitality. Because of very high and wide range of impedance of the enamel, electric pulp testers use high voltage, high output impedance and alternative current source. Most pulp testers use voltage stimulation method and their stimulating threshold levels significantly depend on each individual. Therefore, a constant current stimulator is necessary to minimize the effect of wide variation in enamel thickness. In this study, we constructed a constant current source type of pulp tester with the maximum current of 150 uA.

• 한국전문물리치료학회지
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• 제19권3호
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• pp.31-39
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• 2012

The lower trapezius muscle is an important stabilizer and primary mover of the scapula. The potential use of ultrasound imaging to evaluate scapular muscle function warrants investigation. The purpose of this study is to use ultrasound imaging for determining the effectiveness of 4 different isometric exercises for maximally activating the lower trapezius muscles in healthy subjects. Twenty-eight (14 men and 14 women) volunteers were recruited for this study. Thickness measurements of the lower trapezius muscles were recorded during 4 exercises: latissimus pulldown (LP), prone V-raise (PV), prone row (PR), and modified prone cobra (MP). Lower trapezius muscle thickness was measured 3 times by 2 investigators at a point 3 cm lateral to the lateral edge of the T8 spinous process. The order of 4 exercise execution was randomized for each participant. To identify statistical significance, one-way ANOVA with repeated measures was used with the significance level of .05. Intraclass correlation coefficient (ICC) for intra-reliability was .86~.98 and inter-rater reliability .83~.96 for the lower trapezius, respectively (p<.01). Thickness changes in the lower trapezius muscles between the relaxed and contracted states in men were as follows: LP ($7.37{\pm}2.68mm$, 182%), MP ($4.69{\pm}1.74mm$, 167%), PV ($4.52{\pm}1.47mm$, 149%), and PR ($3.84{\pm}1.72mm$, 133%). In women the values were as follows: LP ($4.64{\pm}1.24mm$, 163%), MP ($2.79{\pm}.81mm$, 131%), PV ($2.78{\pm}.85mm$, 129%), and PR ($2.21{\pm}1.26$ mm, 100%). Thickness of the lower trapezius muscles significantly differed between exercises in both the gender (p<.01). The LP was the most effective exercise for increasing the activation of the lower trapezius muscle in both the gender. We recommend performing the LP exercise for strengthening the lower trapezius muscles.

• 한국세라믹학회지
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• 제32권1호
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• pp.95-105
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• 1995

Ceria(CeO2) stabilized zirconia(CeSZ) sol was synthesized with zirconium n-butoxide Zr(OC4H9)4 and cerium nitrate hexahydrate Ce(NO3)3.6H2O as precursors and ethylacetoacetate(EAcAc) as a chelating agent under atmosphere. CeSZ films were deposited on AISI 304 stainless steel using the prepared polymeric sol by dipcoating and the coating characteristics were investigated by XRD, ellipsometry, scratch test and SEM. The CeSZ film began to crystallize from amorphous to tetragonal phase at 40$0^{\circ}C$ and it was not converted into monoclinic phase up to 100$0^{\circ}C$ by the addition of 16mol% CeO2 as a stabilizer which could suppress phase transformation of zirconia. The CeSZ films were prepared by varying the EAcAc contents and the cncentration of CeSZ sol and measured the thickness and refractive index. From these results, it was found that the EAcAc contents and concentration of CeSZ coating sol evidently affect the densification of CeSZ film. The CeSZ film coated with 0.4M CeSZ sol and heat-treated at $600^{\circ}C$ for 10min had thickness of 50nm and 17% porosity. The CeSZ film on 304 stainless steel effectively acted as a protective layer against oxidation up to 80$0^{\circ}C$ and had superior corrosion resistance in 25% H2SO4 solution for 4.5 hrs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.190-190
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• 2010

The resistance and recovery properties of the YBCO thin-film wire according to the existence and thickness of an insulting layer, and the kinds of stabilization layers, were analyzed at 90 K, 180 K and 250 K. In this study, YBCO thin-film wires with different stabilizing layers and with insulating layers were examined in terms of their various characteristics, such as quenching occurrence, spread, and distribution, based on their resistance increase trends and their recovery from quenching, and the results were qualitatively explained. The results of this study on the characteristics of YBCO thin-film wires' superconducting and normal-conducting phase changes are expected to be useful in designing superconducting power machines and in improving their performance.

• 마이크로전자및패키징학회지
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• 제15권2호
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• pp.17-21
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• 2008

Sn-Cu계 솔더 범프에서 무전해도금법을 이용한 범프 형성에 대한 연구를 하였다. $20{\mu}m$ via에 전기도금법으로 구리를 채운 웨이퍼 위에 ball형태의 범프를 형성하기 위하여 구리와 주석을 도금하여 약 $10{\mu}m$높이의 범프를 형성하였다. 구리 범프 형성 시 via위에 선택적으로 도금하기 위하여 활성화 처리 후 산세처리를 실시하고 무전해 도금액에 안정제를 첨가하였다. 무전해도금법을 이용하여 주석 범프 형성 시 도금층이 구리 범프에 비해 표면의 균일도가 벌어지는 것으로 관찰되었지만 reflow공정을 실시한 후 ball 형태의 균일한 Sn-Cu 범프를 형성하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.69-69
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• 2001

We report a study of the nitriding of the martensitic grade of stainless steel AKSK 420 in a low-pressure rl discharge using pure nitrogen. Much studied samples of the austenitic grade AISI 304 were treated at the same time to provide a comparison. With a treatment time of 4.0 h at $400^{\circ}C$, the nitrogen-rich layer on MSK 420 is 20pm thick and has a hardness about 4.3 times higher than that of the untreated material. The layer thickness is much greater than that obtained on AISI 304 under identical treatment conditions, reflecting the different Cr content of the two alloys. The alloy AlISI 420 is more susceptible than AISI 304 to the formation of CrN and ferrite, and this has a deleterious effect on the hardnes, gain. Below the temperature at which CrN forms, the treated layer retains its martensitic structure, but with a larger lattice parameter than the bulk, a phase that we term expanded martensite, by analogy with the situation with austenitic stainless steel. The fact that the treated layer retains a martensitic structure is interesting in view of previous evidence that nitrogen is an austenite stabilizer.

• 한국환경복원기술학회지
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• 제18권6호
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• pp.201-214
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• 2015

This study was conducted to identify forest topsoil's usefulness from July 2013 to Oct 2014. Generally, there are abundant seeds in topsoils and it can be used at restoration works. Mt. GARIWANG is famous for biodiversity in Korea. This study was aimed to find out the suitable utilization methods of natural topsoils for restoration works at sky-slopes construction sites. Test beds was made to identify suitable collecting times and suitable topsoil thickness. The main results are summarized as follows. First, Mt. GARIWANG have diverse species and in topsoils we can find lots of burried seeds which can be used at restoration works. Second, according to indoor experiment, as the depth of topsoil used thicker, the number of plants and coverage rates were increased. Also, there were no distinct differences in coverage rates between 5cm and 8cm thick topsoil plots and it can be possible to use at least 3cm thick topsoils even thou lower coverage rates. Third, as the results of research about indoor and outdoor experimental plots, there were difference in plant emergency. If we use the stabilizer to protect soil erosion, then we can get more increased results at sloped outdoor experimental plots. Fourth, based on environmental impact assessment, there was 389 species in whole region of Mt. GARIWANG. Through this seed bank experiments, we can find 23 varieties, including 4 tree varieties and 19 herbaceous varieties. We can find lots of native herbaceous species from topsoils. Fifth, this research was done at the specific area of Mt. GARIWANG and used limited topsoils. But we monitoring more longer periods, then there will be more useful outcomes. Finally by researching topsoils of Mt. GARIWANG, we can find diverse native plants. Thus, we must reuse natural topsoils of Mt. Gariwang for restoration of original vegetation.

• 한국화재소방학회논문지
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• 제14권2호
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• pp.33-38
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• 2000

전자산업의 공정에서 PCB기판납땜은 괼수적이며 이에 사용하는 Flux내 용제인 IPA(Iso--propyl alcohol)와 메탄올은 인화성과 폭발성이 강한 물질로 화재위험성이 대단히 높다. 또한 메탄올은 유독성물질로 지정되어 있으며, 환경법상 VOC(Volatile Organic Compound : 휘발성유기화합물)규제물질로 지정되어 있어 대체물질 개발이 절실히 요구된다. 이에 기존 Flux특성을 가지고 있으면서 화재위험성은 없고, 휘발성유기화합물 규제물질에는 해당되지 않는 디클로로프로판(Dichloropropane, DCP)를 주성분으로 하여 Flux 특성에 맞는 안정제 및 첨가제를 적정 조성비로 조합하여 용제를 개발하였다. 그 결과 200ppm의 작업환경허용농도를 470 ppm으로 완화시킬 수 있었으며 납땜불량율은 0.083%에서 0%로, 퍼짐성은 85%에서 87%로, 전연저항은 1.0$\times$$10^{12}$$\Omega$에서 6.9$\times$$10^{12}$/$\Omega$으로 기존 Flux보다 우수하였다. 그러므로 Flux의 안정성은 물론 환경안전측면과 품질, 생산성도 향상이 가능함을 확인하였고, 품질 특성시험 및 제품 신뢰성 시험 결과 만족할 만한 곁과를 얻었다.

• Journal of Pharmaceutical Investigation
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• 제32권4호
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• pp.277-284
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• 2002

Lansoprazole, pharmaceutics for acid-related diseases, is unstable in low pH environments and generally coated with enteric polymer to obtain gastroresistance in stomach. Because its storage stability is influenced by acidic substitutes of enteric polymer, alkaline chemicals wεre generally addεd to dosage form as a stabilizer. In this experience, we coated lansoprazole bead with sodium alginate and evaluated the effect of bead size and sodium alginate coating on the storage stability and dissolution profile of lansoprazole. Sodium alginate solution containing lansoprazole was sprayed as a droplet into 3% (w/v) $CaCl_2$ solution and the resultant bead was coated with starch, sodium alginate, and hydroxypropyl methylcellulose phthalate. The content of lansoprazole granule not coated with sodium alginate decreased to 57.96% of initial content when stored at a severe condition for 4 weeks, but that of lansoprazole granule coated with sodium alginate before enteric coating decreased little and as the thickness of sodium alginate film increased, the content of bead didn't decreased for 4 weeks. Sodium alginate film also improved the gastroresistance without much influencing the maximum dissolution rate.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.95-95
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• 2009

Zinc coatings provide the most effective and economical way of protecting steel against corrosion. There are three types of galvanizing lines typically used in production line in galvanizing industries,Galvanize (GI) coating (Zn-0.1-0.3%Al), Galfan coating (Zn-5%Al), Galvalume(GL) coating (45%Zn-Al). In continuous Galvanizing lines, the immersed bath hardware (e.g. bearings, sink, stabilizer, and corrector rolls, and also support roll arms and snout tip) are subjected to corrosion and wear failure. Understanding the reaction of these materials with the molten Zn alloy is becomes scientific and commercial interest. To investigate the reaction with molten Zn alloys, static immersion test performed for 4, 8, 16, and 24 Hr. Two different baths used for the static immersion, which are molten Zn and molten Zn-55%Al. Microstructures characterization of each of the materials and intermetallic layer formed in the reaction zone was performed using optical microscope, SEM and EDS. The thickness of the reaction layer is examined using image analysis to determine the kinetics of the reaction. The phase dominated by two distinct phase which are eutectic carbide and matrix. The morphology of the intermetallic phase formed by molten Zn is discrete phase showing high dissolution of the material, and the intermetallic phase formed by Zn-55wt%Al is continuous. Aluminum reacts readily with the materials compare to Zinc, forming iron aluminide intermetallic layer ($Fe_2Al_5$) at the interface and leaving zinc behind.