• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.377-385
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• 2015

The span-lengthening of PSC I girder has increased the risk of lateral instability of the girder with the increases in the aspect ratio and self-weight of the girder. Recently, collapses of PSC I girder during construction raise the necessity of evaluating the lateral instability of the girder. Thus, the present study evaluated the lateral behavior and instability of PSC I girders under wind load, regarded as one of the main causes of the roll-over collapse during construction. Lateral instability of the girder is mainly dependent on the length of the girder and the stiffness of the support. The analysis results of this study showed the decrease in the critical wind load and the increase in the critical deformation and angle of the girder, leading to the lateral instability of the girder. Finally, this study proposed analytical equations that can predict the critical amount of wind load and lateral deformation of the girder, which would provide quantitative management values to maintain lateral stability of PSC I girder during construction.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.87-93
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• 2020

The purpose of this study was to examine the convergence correlation between physical characteristics and functional movement screen(FMS). Overall, 193 adults with normal single measurement values participated in the study. For data analysis, we used the SPSS Ver. 26.0 statistical program to perform t-tests and to determine Pearson's correlation coefficients for variables. Data analysis revealed significant sex differences in the active straight-leg raise and trunk stability push up tests (P<.05). In addition, our data analysis also revealed a negatively correlation between body fat percentage and FMS tests, except in the shoulder mobility and active straight leg raise test. In the active straight leg raise, the quality of functional movement was higher in women than in men; while in the trunk stability push ups, the quality of functional movement was higher in men than in women. Therefore, we conclude that men should reinforce the flexibility of the lower extremities, and females should apply upper body muscular strength for better trunk stability movement.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.4
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• pp.285-294
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• 2010

As there are increasing number of tunneling works these days, shotcrete is used as primary supports in order to secure the stability of tunnels. The quality of shotcrete has a direct influence on tunnels, because it is a primary support which secures the stability of completed tunnels as well as the stability of tunnels under excavation. Especially in case that ordinary shotcrete is used under weak rock conditions or at water gushing sections, more shotcrete is needed and rebound ratio increases. As a result, it is hard to keep economic feasibility. In addition to it, in subway construction, there are cases of separated excavation and it may have a bad influence on construction period or quality. Therefore, in this study, we are going to evaluate the early strength of powder type accelerator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.681-693
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• 2019

Multi-use ophthalmic solutions are used many times after opening; therefore, there is a high possibility of decreased quality during use. This study was conducted to determine the recommended use period of multi-use ophthalmic solutions based on evaluation of the stability by comparing stability evaluation regulations of the USA, EU and Korea We selected four types of multi-use ophthalmic solutions (Olopatadine (Olo), Fluorometholone (Flu), Dorzolamide (Dor), Timolol (Timol)) that are frequently marketed in Korea and evaluated their stability during storage according to the actual usage method after opening. The Olo had a decrease in assay and preservative content at 2 months after opening, while Flu showed a significant difference from day 28 after opening. For Dor, significant differences were observed from day 14 after opening in the assay and impurity test item and Timol showed a significant difference from day 28 after opening. Based on the results of the stability test Olo and Flu should only be used within 28 days of opening, while Dor and Timol should be used within 14 days of opening. Therefore, we suggest that regulations system related use periods of multi-use ophthalmic solutions designed as aseptic preparations should be improved based on the results of stability tests after opening.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.1022-1027
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• 2004

The monacolin K content was determined to investigate the stability of monacolin K from red yeast rice after heating (20∼8$0^{\circ}C$), adjusting the pH (2∼8) by adding 3 N HCl or 3 N NaOH, adding the organic acid (6.0% acetic acid, 0.6% citric acid, 1.5% lactic acid) to pH 4.0 and adding the water (0∼80%). And the monacolin K was isolated from red yeast rice by conducting open column chromatography using neutral aluminum oxide. As a result, the stability of monacolin K decreased with increasing the temperature. The stability for pH was in the order of the unadjusted pH (pH 5.9)>8>4 and pH 2>10. The stability for organic acid was high in the order of lactic acid>citric acid>acetic acid, and the stability of monacolin K under acid was different according to the acid type. The degradation rate of monacolin K increased with increasing the water content. Moreover monacolin K was able to isolate from red and pink pigments as well as the other noncoloric compounds in red yeast rice. The yield of monacolin K was found to be 70%.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.510-513
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• 2012

Palladium particles were synthesized by conventional chemical reduction method with ionic liquids. The size and shape of palladium particles were significantly affected by the cation parts of ionic liquids. This is mainly attributed to the different stabilities of the ionic liquid structure formed by the physical bond between the cation parts. Among ionic liquids with [$BF_{4}$] as an anion part, the hexyl substituent in the cation parts was more effective to synthesize palladium particles with the smaller size and more uniform shape.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.19-24
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• 2005

수소 여과용 치밀질 membrane의 제조는 기존의 SC($SrCeO_3$)보다 높은 여과특성을 가지는 BC($BaCeO_3$)구조의 재료를 이용하여 시편을 제조하였고, 시편의 물성은 기공율, 수분에 대한 내구성 그리고 여과 특성을 측정하였다. 우선 열적 안정성 및 수분에 대한 내구성 향상은 $Y_2O_3$를 0.1mol첨가 하였을 때 1% 이내의 기공율을 가지고 있었으며 수분에 대한 안정성을 위해 boiling test에서도 균열이 발생되지 않고 안정적인 것을 확인할 수 있었다. 또한 여과 특성을 향상시키기 위해 Ce과 치환이 가능하고 전도성을 향상시킬 수 있는 $Ga_2O_3$, $La_2O_3$을 치환하여 물성을 측정한 결과 $Ga_2O_3$은 0.05, $La_2O_3$ 0.1mol%가 최적이었으며, 이들 중 $Ga_2O_3$가 0.05mol 첨가 되었을 때 가장 높은 이온 전도도 값을 얻었으며, $La_2O_3$이 첨가된 경우가 다음으로 높게 나타났다. 전자 전도성을 높이기 위하여 Pt를 sol로 만들어 나노 입자로 분산 시키는 방법으로 실험을 실시 $500^{\circ}C$ 이상의 온도에서는 복합전도에 의해 전도도가 향상되어지는 것을 확인할 수 있다. 또한 이들 시편의 여과 특성을 측정한 전도도 측정의 결과와 동일한 결과를 얻을 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.156-157
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• 2008

반도체 소자 회로의 집적도가 높아짐에 따라 선폭이 감소하였고 고온 공정이 필요하게 되었다. 기존의 반도체 회로 배선 재료인 Al을 사용할 경우 소자의 속도가 느려져서 소자의 신뢰도가 떨어지고 고온공정에서의 문제가 발생되어 이를 해결하기 위한 차세대 배선 물질로 비저항이 낮은 Cu의 사용이 요구되고 있다. 하지만 Cu는 Si와의 확산이 잘 일어나기 때문에 그 사이에서 확산을 막아주는 확산방지막에 대한 필요성이 제기되었고 연구가 활발히 진행되고 있다. 본 논문에서는 Cu와 Si사이의 확산을 방지하기 위한 W-C-N 확산방지막을 물리적 기상 증착법(PVD)중 하나인 RF Magnetron Sputtering 방식을 사용하여 증착하였다. 고온 공정에서의 안정성을 알아보기 위해 $600^{\circ}C$ 부터 $900^{\circ}C$ 까지 $100^{\circ}C$ 단위로 열처리를 하였고 4-point probe 장치를 사용하여 열처리 온도에 따른 비저항 측정을 통해 W-C-N 확산방지막의 특성을 분석하였다.

• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.215-224
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• 2021

In this study, to investigate the effect of stabilization of Pb-contaminated soil near a smelter site for the reduction of environmental risk of Pb leaching, commercial stabilizers were amended with the Pb-contaminated soil and evaluated leaching characteristics of Pb in soil by TCLP and SPLP leaching test. Also, performing sequential extraction procedure speciation of Pb in the amended soil was investigated. Limestone, AC-2 (Amron), Metafix (Peroxychem) that possess stabilization performance towards heavy metal in soil and mass production is available were selected as candidates. AC-2 contained a CaCO₃ and MgO crystalline phase, while Metafix had a Fe₇S₈ crystalline phase, according to XRD studies. Pb content in SPLP extract was lower than the South Korean drinking water standard for Pb in groundwater at 4% AC-2 and Metafix treatment soil, and TCLP-based stabilization effectiveness was more than 90%. The findings of the sequential extraction method of soil treated with Metafix revealed that fractions 1 and 2 of Pb, which correspond to relatively high mobility and bioavailable fractions, were lowered, while the residual fraction (fraction 5) was raised. As a consequence, the order of performance for Pb stabilization in polluted soil was Metafix>AC-2>limestone.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.272-279
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• 2013

The concept of implant stability was basically originated from the relative condition of bone-implant interface and has some meanings for evaluation of that interface. In addtion, it has been used for the investigation of initial bone healing process after fixture installation because a degree of micromotion around interface can affect unfavorable clinical results. The purpose of this study is to investigate the mode of initial bone healing from fixture installation through prospective trial. Thirty fixtures were consecutively installed in mandibles of 26 patients with single tooth loss area and then healing abutment were secured for one-stage surgery meothod. Resonance frequency analysis was performed with one week interval during 12 weeks and periapical radiographs were taken at each month. Although marginal bone level change was not shown through observation period (P>0.05), statistical difference of implant stability was shown through 4 and 6 week (P<0.05) and was not shown after 6 week (P>0.05) according to the bone quality. Initial bone healing process is a successive process of bone resorption and favorable bone healing result might be postulated at 4 week interval after installation through RFA.