• 공업화학
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• 제29권6호
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• pp.799-804
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• 2018

결정화조작에 의해 접촉분해경유(LCO) 유분 중에 함유된 2,6-디메틸나프탈렌(2,6-DMN)의 분리 정제를 검토했다. LCO 유분을 원료로, 이소프로필알코올을 결정화 용매로 각각 사용하여 solute crystallization (SC)을 수행했다. 결정화 조작온도의 상승과 용매/원료의 체적비(S/F)의 증가는 2,6-DMN의 순도를 향상시켰으나, 역으로 수율의 저하를 초래시켰다. LCO 유분(13.9% 2,6-DMN)과 이소프로필알코올을 사용한 SC, SC에 의해 회수한 결정과 메틸아세테이트를 사용한 re-crystallization 1 (RC 1), RC 1에 의해 회수한 결정과 메틸아세테이트를 사용한 RC 2의 3단계로 결정화조작을 행한 결과, 19.5%의 수율로 99.9% 2,6-DMN의 결정을 회수할 수 있었다. SC, RC 1, RC 2의 각 조작을 통해 얻어진 실험적 결과를 이용하여 LCO 유분 중에 함유된 2-6-DMN의 분리 정제공정을 검토했다.

• 열처리공학회지
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• 제35권3호
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• pp.150-158
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• 2022

The effects of scandium addition on the Al-6Si-2Cu Alloy were investigated. The Al-6Si-2Cu-Sc alloy was prepared by gravity die casting process. In this study, scandium was added at 0.2 wt%, 0.4 wt%, 0.8 wt%, and 1.0 wt%. The microstructure of Al-6Si-2Cu-Sc alloy was investigated using Optical Microscope, Field Emission Scanning Electron Microscope, Electron Back Scatter Diffraction, and Transmission Electron microscope. The microstructure of Al-6Si-2Cu alloy with scandium added changed from dendrite structure to equiaxed crystal structure in specimens of 0.4 wt% Sc or more, and coarse needle-shape eutectic Si and β-Al₅FeSi phases were segmented and refined. The nanosized Al₃Sc intermetallic compound was observed to be uniformly distributed in the modified Al matrix.

• 한방재활의학과학회지
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• 제30권3호
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• pp.1-21
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• 2020

Objectives This study was designed to evaluate the bone regeneration effects of Sintongchukea-tang (SC) on rib fractured rats. Methods Rats were randomly divided into 5 groups (normal, control, positive control, SC low [SC-L] and SC high [SC-H]). All groups were subject to fractured rib except normal group. Normal group received no treatment at all. Control group was orally fed with phosphate buffered saline, and positive control group was medicated with tramadol (20 mg/kg). SC group was orally medicated with SC (50 mg/kg, 100 mg/kg) once a day for 14 days. The fracture healing process was observed by x-ray, micro CT and fracture tissue slide was observed by immunohistochemical staining. We analysed levels of transforming growth factor-β1, Ki67, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), receptor activator of nuclear factor kappa-β, tartrate resistant acid phosphatase (TRAP) and analysed levels of Osteocalcin in plasma. We measured levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), ALP, blood urea nitrogen (BUN) and creatinine in plasma, for hepatotoxicity and nephrotoxicity of SC. Results Though X-ray and micro-computed tomography, more callus formation was observed and bone union was progressing. Through Hematoxylin and Eosin, callus formation was increased compared to the control group. Runx2 level at SC-H was significantly increased and TRAP level at SC-L was significantly decreased compared with the control group. AST, ALT, ALP, BUN and creatinine were not statistically different from the control group. Conclusions As described above, SC promoted fracture healing by stimulating the bone regeneration factor. And SC shows no hepatotoxicity and nephrotoxicity. In conclusion, it seems that SC helps to promote fracture regeneration and it can be used clinically to patients with fracture.

• 식물병연구
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• 제18권2호
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• pp.123-128
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• 2012

We investigated the resistance of 50 commercial Chinese cabbage cultivars against clubroot disease caused by Plasmodiophora brassicae in the three difference fields, Suwon, Hwacheon, and Pyeongchang. Wilting symptom on Chinese cabbage was first observed at 15 days after transplanting in Pyeongchang and Hwacheon, while disease symptoms appeared later in Suwon after the rainy season. Among 50 cultivars, eight cultivars, SC26, SC29, SC30, SC31, SC34, SC46, SC47 and SC50 showed highly susceptible symptoms like wilting and heavy root galls in all three fields. Meanwhile, seven cultivars such as SC05, SC06, SC07, SC09, SC11, SC17, and SC36 showed moderate resistance with delayed wilting and few root galls. Only two cultivars, Chuwol (CB22) and Gohyangssam (CB23) were highly resistant to clubroot disease until the harvest season in all of the three fields. These two commercial cultivars may be considered as candidate cultivars for cultivation of organic Chinese cabbage in Suwon, Hwacheon, and Pyeongchang.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
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• pp.111.2-111
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• 2002

• Korea-Australia Rheology Journal
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• 제20권4호
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• pp.235-243
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• 2008

The aim of this study is to explore the possibility of incorporating supercritical carbon dioxide ($scCO_2$) into twin screw extrusion process for the production of polypropylene-clay nanocomposite (PPCN). The $CO_2$ is used as a reversible plasticizer which is expected to rapidly transport polymeric chains into the galleries of clay layers in its supercritical condition inside the extruder barrel and to expand the gallery spacings in its sub-critical state upon emerging from die. The structure and properties of the resulting PPCNs are characterized using wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), rheometry, thermogravimetry and mechanical testing. In the processing of the PPCNs with $scCO_2$, optimum $scCO_2$ concentration and screw speed which maximized the degree of intercalation of clay layers were observed. The WAXD result reveals that the PP/PP-g-MA/clay system treated with $scCO_2$ has more exfoliated structure than that without $scCO_2$ treatment, which is supported by TEM result. $scCO_2$ processing enhanced the thermal stability of PPCN hybrids. From the measurement of linear viscoelastic property, a solid-like behavior at low frequency was observed for the PPCNs with high concentration of PP-g-MA. The use of $scCO_2$ generally increased Young's modulus and tensile strength of PPCN hybrids.

• 한국세라믹학회지
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• 제53권5호
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• pp.500-505
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• 2016

Scandia-stabilized zirconia co-doped with $CeO_2$ is a promising electrolyte for intermediate temperature SOFC, but still shows rapid degradation during a long-term operation. In this study, $CeO_2$ (1 mol%) as a stabilizer is partially substituted with lanthanum oxides ($M_2O_3$, M=Yb, Gd, Sm) to stabilize a cubic phase and thus durability in reducing atmosphere. 0.5M0.5Ce10ScSZ electrolytes were prepared by solid state reaction and sintered at $1450^{\circ}C$ for 10 h to produce dense ceramic specimens. With addition of the lanthanum oxide, 0.5M0.5Ce10ScSZ showed lower degradation rates than 1Ce10ScSZ. Since $Gd_2O_3$ showed the highest ionic conductivity among the co-dopants, an electrolyte-supported cell with 0.5Gd0.5Ce10ScSZ was prepared to compare its long-term performance with that of 1Ce10ScSZ-based cell. Maximum power density of 0.5Gd0.5Ce10ScSZ-based cell was degraded by about 2.3% after 250 h, which was much lower than 1Ce10ScSZ-based cell (4.2%).

• 한국산업정보학회논문지
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• 제26권6호
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• pp.1-9
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• 2021

주파수 전송 효율을 높이기 위하여 주파수 대역에서의 켤레 복소수 대칭 특성을 갖는 단일 측대 파형 전송 시스템의 연구가 이루어지고 있다. 또한, 직교 블록 부호(시공간 및 주파수 공간 블록 부호)를 활용한 전송 시스템의 다이버시티 성능 이득에 대하여 많은 연구가 진행되어 왔다. 본 논문에서는 4개의 송신 안테나를 갖는 3/4 비율의 주파수 공간 블록 부호 단일 측대 파형 SC(single carrier) FDMA(frequency division multiple access) 시스템을 구현한다. 3/4 비율의 4×4 직교 블록 부호를 적용함으로써 기존의 단일 안테나 기반 단일 측대 파형 SC FDMA 시스템과 2개의 송신 안테나를 이용한 2×2 주파수 공간 블록 부호 단일 측대 파형 SC FDMA 시스템보다 뛰어난 수신 성능을 확보할 수 있음을 실험 결과를 통해 확인할 수 있다.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.1-9
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• 2021

In the Internet of Thing (IoT) framework, massive machine-type communications (MMTC) have required large spectral efficiency. For this, non-orthogonal multiple access (NOMA) has emerged as an efficient solution. Recently, a non-successive interference cancellation (SIC) NOMA scheme has been implemented without loss. This lossless NOMA without SIC is achieved via correlated superposition coding (SC), in contrast to conventional independent SC. However, conventional minimum high-correlated SC for only 2-user NOMA schemes was investigated in the lossless 2-user non-SIC NOMA implementation. Thus, this paper investigates a 3-user low-correlated SC scheme, especially for an inflated achievable sum rate, with a design of 3-user low-correlated SC. First, we design the 3-user low-correlated SC scheme by taking the minimum sum rate between 3-user SIC NOMA and 3-user non-SIC NOMA, both with correlated SC. Then, simulations demonstrate that the low correlation in the direction of the first user's power allocation inflates the sum rate in the same direction, compared to that of conventional minimum high-correlated SC NOMA, and such inflation due to low correlation is also observed similarly, in the direction of the second user's power allocation. Moreover, we also show that the two low correlations of the first and second users inflates doubly in the both directions of the first and second users' power allocations. As a result, the proposed 3-user low-correlated SC could be considered as a promising scheme, with the inflated sum rate in the future fifth-generation (5G) NOMA networks.

• 자원환경지질
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• 제49권6호
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• pp.469-477
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• 2016

국내 이산화탄소 지중저장 저장암의 저장성능을 평가하기 위하여, 이산화탄소 주입 시 저장암 내 공극수와 대체되는 초임계이산화탄소($scCO_2$)량을 실험실에서 측정하는 기술을 개발하였다. 국내 $CO_2$ 육상 지중저장 후보지로 판단되는 장기분지 사암과 역암에 대하여, 지중 저장 조건에서 $scCO_2$를 저장암 내부로 주입하는 경우, 공극 내 존재하는 지하수를 대체하여 저장되는 $scCO_2$ 대체저장효율(displacement efficiency)을 측정하였다. 국내 육상 지중저장 후보지인 장기분지 주변 대심도 시추공에서 채취한 사암과 역암 코어를 훼손하지 않고 그대로 사용하여 대체저장효율을 측정할 수 있는 '이중벽 고압셀'을 제작하였다. 시추한 암석 코아를 원형 그대로 고압셀 내부에 밀착시켜 $scCO_2$를 암석 공극 내 충분히 주입 한 후, 공극에 포화되어 있던 지하수와 대체된 $scCO_2$ 대체저장효율을 측정한 결과, 장기분지 역암과 사암의 평균 $scCO_2$ 대체저장효율은 각각 31.2%와 14.4%이었다. 장기분지 역암과 사암의 $scCO_2$ 저장량을 계산하기 위하여 대심도 시추 자료, 시추 부지 주변 지질조사 및 물리탐사 자료로부터 주입 후보지 하부에 존재하는 장기분지 역암과 사암층의 평균 두께를 각각 50 m, 두 지층의 연장 면적을 주입공 주변으로 반경 250 m로 가정하였다. 실험으로부터 얻어진 $scCO_2$ 대체저장효율, 평균 유효 공극률, 지중저장 조건에서 $scCO_2$의 밀도값 등을 이용하여 계산된 시추공 주변 하부 장기분지 역암과 사암층의 $scCO_2$ 저장량은 264,592 t (metric ton)으로 계산되었다. 본 실험결과로부터 대심도 시추공 주변 장기분지의 역암과 사암층은 수 만톤 규모의 $CO_2$ 주입과 저장 실증 시험을 위해 충분한 저장성능을 보유하고 있는 국내 육상 $CO_2$ 지중저장 후보지임을 입증하였다.