• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.477-485
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• 2010

Various monitoring sensors are used to predict and detect structural damage. Smart sensors, such as glass-fiber sensors, PZT, and MEMS, among others, have replaced traditional sensors. They are now being used in many areas. This study aims to predict the damage by measuring the PZT voltage attached on the specimen by the applied impact load. In the experiment to detect damages in beam connection, simple $H-400{\times}200{\times}8{\times}13$ beams were spliced with bolts. The results of FFT between PZT sensor and accelrometer were compared to measure the sensitivity of the PZT sensor. The damage to the beam was presumed by loosening the bolt, and then the damage measurement was accompanied. Secondly, a steel $PL600{\times}65{\times}5.8$ plate beam was fabricated for the purpose of experimenting on damage measurement. Impact loading test on three different locations was carried out. Damage width varied between 6~42mm on both sides by cutting, using a steel saw. The ratio of frequencies before and after the damage was computed to quantify the damage level by using FFT, and the change in mode pattern with the increased damage was investigated to measure the damage.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.13-18
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• 2020

Iron oxide nanoparticles were microencapsulated using fibroin, a protein polymer of silk fiber, for theragnostic applications. The content of iron oxide was determined to be 4.28% by thermogravimetric analysis and 5.11% by magnetometer. A suspension of murine fibroblast 3T3 cells grown in medium supplemented with iron oxide-microcapsules turned clear in response to the magnetic force and the cells aggregated to the magnet direction. Neodymium magnets placed on the top of the culture dish, and attracted cells to the center of the culture surface. The cells collected on the culture surface aggregated to form a rough spheroid of 2 mm in a diameter after 72 h. In the outer layer of the cell aggregate, cells were relatively large and gathered together to form a dense tissue, but the central part was observed to undergo cell death due to the mass transfer restriction. In the outer layer, iron oxide-microcapsules were lined up like chains in the direction of magnetic force. Using microCT, it was demonstrated that the iron oxides inside the cell aggregate were not evenly distributed but biased to the magnetic direction.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.441-448
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• 2016

Heavy metal removal study is conducted from synthetic waste water by reduction and oxidation(redox) reaction of Cu-Zn metal alloy and adsorption reaction of aluminium silicate. Heavy metal whose ionization tendency is smaller than zinc are reducted in an aqueous solution, and the concentration of ionized zinc is reduced by adsorption reaction. The average diameter of metal alloy micro fiber is about $200{\mu}m$, and the surface area is wide enough to get equilibrium in a single cycle treatment. A single cycle treatment of redox reaction of Cu-Zn metal alloy, could remove 100.0 % of Cr(III), 98.0 % of Hg, 92.0 % of Sn and 91.4 % of Cu respectively. An ionization tendency of chromium is very close to zinc, but removal efficiency of chromium by redox reaction is significant. This result shows that trivalent chromium ion is expected to generate hydroxide precipitation with $OH^-$ ion generated by redox reaction. Zinc ion generated by redox reaction is readily removed by adsorption reaction of aluminium silicate in a single cycle treatment. Other heavy metal components which are not perfectly removed by redox reaction also showed very high removal efficiency of 98.0 % or more by adsorption reaction. Aluminium ion is not increased by adsorption reaction of aluminium silicate. That means heavy metal ion removal mechanism by adsorption reaction is turned out to be not an ion exchange reaction, but an adsorption reaction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.5
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• pp.458-465
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• 2006

This study was carried out to evaluate the nutritional properties of quality protein maize (QPM) and to select the elite lines for corn breeding. Two laboratory procedures for simultaneous identification of QPM and lysine content analysis were performed. The $BC_{1}F_{2}$ lines of KS5/QPM and KS135/QPM were analyzed with opaque-2(o2) specific SSR marker in order to differentiate the opaque-2 carrying QPM lines from the non-opaque genotypes. Although no significant difference in protein content, significant differences in lipid, ash, and crude fiber contents were observed. The composition of unsaturated fatty acid of QPM lines was slightly lower than non-QPM lines, but there was no significant difference. Sulphur-containing amino acids such as methionine and cystine showed no difference between QPM and non-QPM lines. However, lysine content of QPM lines was 38% higher than that of non-QPM lines, and the essential amino acid content of QPM lines (28.1%) was higher compared to non-QPM lines (27.1%).

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.90-90
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• 2012

극세섬유는, 1970년대 말부터 일본의 합섬업체들이 천연소재인 Silk를 모방하기 위해 개발을 시작하였으며, 개발된 섬유의 굵기가 0.5d(1denier=1g/9,000m)이하인 것을 말한다. 이후 극세사에 대한 끊임없는 노력으로, 1980년대에는 천연스웨이드 풍의 인조피혁의 제조가 가능한 0.1d이하급 초극세사가 N/P(Nylon/Polyester) 복합방사된 형태로 개발되었으며, 일본, 및 한국 등에서 이들 소재로 제조된 직편물 제품이 첨단 고부가소재로서 호황을 누려왔다. 이러한 초극세사는 다양한 형태로 발전되어왔는데, 해도형(Islands-in-a-Sea Type), N/P(Nylon/PET), P/N(PET/Nylon) 등이 대표적인 형태이며, 가공공정 중에서 분할이 되면서 그 특성을 발현한다고 하여 분할사, 형태에 따라서 N/P 분할사라 하기도 한다. 최근들어 이러한 N/P 분할사는 기존의 의류용 용도뿐만 아니라, Wiping Cloth, 극세사 타울, 항진드기용 침장 등 다양한 비의류용 소재로도 확대 전개되고 있으며, 이렇게 다양화 되어가고 있는 용도에 따른 공정별 최적 가공 방법에 대한 연구가 진행 중이다. 사가공 공정에 있어서는 텍스쳐링 방법이 적용되기도 하는데, 가장 보편화된 텍스쳐링 방법으로는 DTY(Draw Texturing Yarn), ATY(Air Texturing Yarn) 등의 형태가 있으며, 이러한 텍스쳐링 방법은 물성에 민감한 N/P 분할사의 강도, 신도, 분할도에 영향을 미치게 된다. 본 연구에서는 기존의 텍스쳐링 방법이 아닌 Fancy사 형태로 사가공을 하였으며, 직물로 제직하고, 분할 가공하여 직물로써의 물성까지 분석하였다. Fancy사는 색이나 형의 변화로 디자인효과를 준 실을 말하는데, 심사, 부사, 압사로 이뤄지며 의장사, 장식사 등으로 불려지기도 한다. 주요 공정을 보면, 크릴형성용 부사를 500-600T/M으로 가연한 연사를 얻는 제1공정과, 이 가연된 부사와 심사를 합사하는 제2공정 및 합사된 크릴의 뒤틀림을 방지하기 위하여 압사로 크릴을 고정하여 주는 제3공정으로 이루어진다. 사용된 N/P 분할사는 NP30/36dty, NP50/36dty를 사용하였으며, 부사의 오버피드 및 피드되는 사에 따라 각각 8종, 7종의 Fancy사를 제조하여 섬도(Denier), 강도(Tenacity), 신도(Elongation)를 측정하였다. 또한, 이들 사들로 제직 및 분할가공을 하여 인장강도, 인장신도, 인열강도, 마모강도, 공기투과도 등의 물성과 중량, 두께를 측정하였으며, 온도, NaOH 농도, 시간 등의 분할 가공조건에 따른 직물의 인열강도 변화도 측정하였다. 이렇게 공정별 조건에 따른 물성의 변화분석을 통해 추후 N/P의 제품화 전개에 도움이 되고자 하였다.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.171-175
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• 2011

Lithium secondary batteries using lithium metal count electrode are easy to use and to analyze the specific characteristics of working electrode. Nevertheless, during the charge operation internal electrical short circuit could be caused by the dendritic growth of lithium. The cell failure by the short circuit depends on the condition of separator such as constitutive material and thickness. To prevent the cell failure caused by the dendritic growth of lithium, the electrochemical properties of the cell of lithium metal count electrode were evaluated for four different kinds of separator. Among the tested separators, GMF (glass micro-fiber filter, $300{\mu}m$) was the most promising one because it could effectively prevent the cell failure during the charge. The cell using GMF separator had relatively low impedance. Generally the cell using thicker separator than $50{\mu}m$ could effectively avoid the cell failure by internal short circuit and had the good cycleability. The highest rate capability by the signature method was acquired in the case of GMF separator.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.624-629
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• 2013

The relation between performance maintenance conditions and those cost efficiency was studied to choose an optimum operating condition in the seawater desalination pretreatment system. A hollow fiber microfiltration module, which was developed with domestic technology, was tested with the various operating conditions such as chemically enhanced backwash cycles and design dosages of a cleaning chemical. Transmembrane pressure was measured to investigate membrane fouling status and cleaning degree. In addition, economic analysis was performed to compare water production costs by the operation condition. As a result, The operation mode III, chemically enhanced backwash at once a day with 100 mg/L of sodium hypochlorite (NaOCl) was selected. The concurrent evaluation between membrane filtration performance and its economic analysis will be suitable to choose an efficient optimum condition.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.261-269
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• 2018

The fractional anisotropy value of the basal ganglia fibers in the brain gray matter region was analyzed by Tract-Based Spatial Statics(TBSS) method after acquiring the diffusion tensor image to identify the presence or absence of brain white matter damage to smoking in male. As a result of measurement analysis, the fractional anisotropy measurement value was lower in smokers than non-smokers in all areas, and the FA value was statistically significant. smoking significantly affects all the anatomic micro structural changes in the brain gray matter and damages the nerve fiber tract. As a result, it can affects functional abnormalities related to the minute changes of the brain due to smoking.

• Horticultural Science & Technology
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• v.35 no.3
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• pp.289-299
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• 2017

The objective of this study was to determine the effect of replacing perlite (PL) with pellets processed with poultry feather fiber as an inert material to prepare growing medium. The growth and flowering of Salvia splendens 'Vista Red' grown in individual growing medium $Biosangto^{(R)}$, peat moss (PM), PL, and two pellets (P45-1 and P45-2) were evaluated. Peat moss was mixed with PL, P45-1, or P45-2 at various ratios (1:0 to 1:3 or 3:1 by volume) to investigate the feasibility of replacing PL with pellets. Nutrient composition of the growing medium and leaf tissues was analyzed. The number of florets, inflorescence length, plant height, and fresh weight of plants grown in media containing P45-1 or P45-2 were reduced compared to those grown in individual growing medium PM or PL. As the mixing ratio of P45-1 or P45-2 to PM was higher, the growth of salvia, such as inflorescence length, plant height, number of leaves, and fresh weight was inhibited. Our results indicate that mixing three parts PM with one part of P45-1 (PM/P45-1/3:1) or P45-2 (PM/P45-2/3:1) accelerated flowering and increased the number of florets and leaves compared to other mixing ratios of PM and pellets media. The concentrations of phosphorus (P), calcium (Ca), boron (B), iron (Fe), and copper (Cu) in individual growing medium PL, P45-1, and P45-2 were significantly lower than those in PM. The concentration of N was the highest in leaves of plants grown in P45-1 or P45-2 amended media, and the concentrations of P, Ca, and zinc (Zn) in leaves were lower in individual growing medium P45-1 or P45-2 than in PM and PL. The pH of PM/P45-1/3:1 or PM/P45-2/3:1 media was maintained at optimal level (5.8-5.9) and the concentrations of macro- and micro-elements in the media and leaves were considered to be optimal levels. Therefore, mixing three parts PM with one part P45-1(PM:P45-1/3:1) or P45-2 (PM:P45-2/3:1) is recommended for improved growth and flowering in salvia. This suggests that P45-1 or P45-2 can replace PL as an inert material to prepare growing medium.

• Publications of The Korean Astronomical Society
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• v.24 no.1
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• pp.53-64
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• 2009

MIRIS is the main payload of the STSAT-3 (Science and Technology Satellite 3) and the first infrared space telescope for astronomical observation in Korea. MIRIS space observation camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}\times3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200 K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI (Multi Layer Insulation) of 30 layers, and GFRP (Glass Fiber Reinforced Plastic) pipe support in the system. Optomechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.