• The KSFM Journal of Fluid Machinery
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• v.17 no.2
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• pp.30-34
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• 2014

Membrane distillation (MD) is a thermal driven separation process in which separation a hydrophobic membrane is a barrier for the liquid phase, letting the vapor phase pass through the membrane pores. Therefore, a porous and hydrophobic membrane should be used in membrane distillation. MD cannot work if water penetrates into the pores of the membrane (membrane wetting). Accordingly, it is necessary to prevent wetting of MD membranes and to remove water inside the pores of the wetted membranes if possible. In this context, our study aimed to develop methods to recover wetted membranes in MD processes. Poly-vinylidene fluoride (PVDF) membranes were used in this study. A laboratory-scale direct contact MD (DCMD) system was used to examine the effect of operating parameters on wetting. For dewetting the wetted membranes, specific techniques including the use of high temperature air were applied. The performances of the membranes before and after dewetting were compared in terms of flux, salt rejection and liquid entry pressure(LEP). The surface morphology of dewetted membrane was confirmed by scanning electron microscope (SEM).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.391-391
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• 2010

초전도 가속공동기의 소재는 순수 Nb로 제작하는 것이 일반적이다. 그러나 극저온 (2-4.5K)에서 열전도도가 낮아서 순간적인 Normal zone이 발생되면 이를 원활이 냉각되지 못하여 Quench로 발생 가능성이 높다. 초전도 가속공동기는 약 3 mm 두께의 Nb 판을 이용하는데, 500 MHz 공동기의 전자기장의 침투깊이가 불과 수 nm에 불과해서 나머지 부분은 사실상 불필요한 부분이다. 따라서 이 경우 매우 비싼 초전도 공동기 소재의 낭비가 매우 심하다. 또 Nb 판으로 공동기를 제작할 경우 매우 비싸고 시간이 많이 소요되는 전자빔용접을 해야 하고 또 제작 후 표면처리가 매우 번거롭고 장시간을 요한다. 이러한 단점을 보완하기 위해서 구리판으로 성형가공법을 이용하여 공동기를 제작하고, 내부의 RF 표면에 수 ${\mu}m$ 두께의 Nb 코팅을 한 공동기를 개발하여 CERN의 LEP에 설치하여 실용화하였다. 이렇게 하여 소재비용을 포함한 초전도 공동기 제작, 표면처리 비용 절감은 만족할 만한 결과를 얻었다. 구리의 높은 열전도에 의한 고 가속전기장의 기대와 달리 가속전기장이 최고 약 7 MV/m 정도로 제한되었다. 그후 꾸준히 연구개발을 진행하여 현재 약 22 MV/m 까지 기록하고 있으나, 순수 Nb 공동기의 약 50 MV/m에 비하면 현저히 낮은 수준이다. 본 연구는 Nb 코팅법을 이용하여 Nb 코팅 초전도 공동기의 한계를 넓히기 위한 것이다. 본 발표는 "Sputtering 법에 의한 초전도 Nb coating 소재의 RF 한계 극복 연구"의 기초연구 결과를 보고하고자 한다.

• Membrane and Water Treatment
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• v.13 no.1
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• pp.51-62
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• 2022

Vacuum-assisted air gap membrane distillation (V-AGMD) has the potential to achieve higher flux and productivity than conventional air gap membrane distillation (AGMD). Nevertheless, there is not much information on technical aspects of V-AGMD operation. Accordingly, this study aims to analyze the effect of membrane deformation on flux in V-AGMD operation. Experiments were carried out using a bench-scale V-AGMD system. Statistical models were applied to understand the flux behaviors. Statistical models based on MLR, GNN, and MLFNN techniques were developed to describe the experimental data. Results showed that the flux increased by up to 4 times with the application of vacuum in V-AGMD compared with conventional AGMD. The flux in both AGMD and V-AGMD is affected by the difference between the air gap pressure and the saturation pressure of water vapor, but their dependences were different. In V-AGMD, the membranes were found to be deformed due to the vacuum pressure because they were not fully supported by the spacer. As a result, the deformation reduced the effective air gap width. Nevertheless, the rejection and LEP were not changed even if the deformation occurred. The flux behaviors in V-AGMD were successfully interpreted by the GNN and MLFNN models. According to the model calculations, the relative impact of the membrane deformation ranges from 10.3% to 16.1%.

• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.14-28
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• 1985

The development of mono energetic photon sources using $K_{\alpha}$ fluorescence X-ray of pure material was carried out in the energy range below 100 keV. The monoenergetic photons are very useful in the calibration of the radiation measuring instruments and can be produced as the $K_{\alpha}$ fluorescence X-ray by irradiating the bremsstrahlung to the thin pure metal foils called ‘radiators’. In this experiment, several radiators such as $_{47}Ag,\;_{50}Sn,\;_{68}Er,\;_{70}Yb,\;and\;_{82}Pb$ provide the wide monoenergetic photon energy ranging from 20 keV to 80 keV. By the spectrometry with HpGe LEPS, spectral purity factors which measure the monochrometicity for the $K_{\alpha}$ fluorescence X-ray, were determined as $0.64{\sim}0.94$. Dosimetry for the purpose of the determination of the exposure rate with a 600cc thin window ionization chamber, which was calibrated by the standard free-air ionization chamber, was performed. Exposure rates ranging $8.3{\sim}232.5mR/h$ was obtained according to the $K_{\alpha}$ fluorescence X-ray energy for each radiator.

• Biomedical Science Letters
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• v.16 no.4
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• pp.311-316
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• 2010

We studied a comparison of the concentration of biochemical markers in sera of patients hospitalized with high fever (n=296) in Jeonbuk province during the last 2 years (2008 to 2009). The patients were divided into three patient groups of viral hemorrhagic fever (VHF) patient group tested positive for Hantavirus (n=53), leptospirosis (LEP) patient group tested positive for Leptospira interrogans (n=137) and scrub typhus (TSU) patient group tested positive for Orientia tsutsugamushi (n=106). We analyzed the concentration of ALP, AST, ALT, blood urea nitrogen, creatinine and glucose and compared the mean levels of them to normal range, the first sample and last sample. The frequencies of abnormal patient elevated above the upper limit of normal for ALP, AST and ALT were 18~43.4%, 78~97% and 62.3~92.7% in patient groups, and 24.5~47.4% (total protein) and 13.2~50.0% (albumin) of patients in patient groups had decreased below the lower limit of normal. The patients showed higher abnormal levels of glucose in patient groups were 58.5% (viral hemorrhagic fever patient group), 66.4% (leptospirosis patient group), 71.7% (scrub typhus patient group) and 66.9% (total patient group). There were significant difference between the first sample and the last sample in the mean levels of AST (decreased 22.2% in viral hemorrhagic fever patient group, 30.2% in leptospirosis patient group, 20.4% in scrub typhus patient group and 24.1% in total patient group), BUN (43.0% in viral hemorrhagic fever patient group, 41.6% in leptospirosis patient group, 47.4% in scrub typhus patient group and 43.0% in total patient group) and glucose (20.2% viral hemorrhagic fever patient group, 17.9% in leptospirosis patient group, 18.6% in scrub typhus patient group and 18.9% in total patient group) in the first sample and the last sample. According to these results, those diseases may cause liver damage and have high concentration of ALP, AST, ALT and glucose in blood even though the patients get out of the hospital.

• Journal of Embryo Transfer
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• v.27 no.3
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• pp.175-181
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• 2012

The synovial tissues are a valuable MSCs source for cartilage tissue engineering because these cells are easily obtainable by the intra-articular biopsy during diagnosis. In this study, we isolated and characterized the canine MSCs derived from synovial fluid of female and male donors. Synovial fluid was flushed with saline solution from pre and post-puberty male (cM1-sMSC and cM2-sMSC) and female (cF1-sMSC and cF2-sMSC) dogs, and cells were isolated and cultured in advanced-DMEM (A-DMEM) supplemented with 10% FBS in a humidified 5% $CO_2$ atmosphere at $38.5^{\circ}C$. The cells were evaluated for the expression of the early transcriptional factors, such as Oct3/4, Nanog and Sox2 by RT-PCR. The cells were induced under conditions conductive for adipogenic, osteogenic, and chondrogenic lineages, then evaluated by specific staining (Oil red O, von Kossa, and Alcian Blue staining, respectively) and analyzed for lineage specific markers by RT-PCR. All cell types were positive for alkaline phosphatase (AP) activity and early transcriptional factors (Oct3/4 and Sox2) were also positively detected. However, Nanog were not positively detected in all cells. Further, these MSCs were observed to differentiate into mesenchymal lineages, such as adipocytes (Oil red O staining), osteocytes (von Kossa staining), and chondrocytes (Alcian Blue staining) by cell specific staining. Lineage-specific genes (osteocyte; osteonectin and Runx2, adipocytes; PRAR-${\gamma}2$, FABP and LEP, and chondrocytes; collagen type-2 and Sox9) were also detected in all cells. In this study, we successfully established synovial fluid derived mesenchymal stem cells from female and male dogs, and determined their basic biological properties and differentiation ability. These results suggested that synovial fluid is a valuable stem cell source for cartilage regeneration therapy, and it is easily accessible from osteoarthritic knee.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.221-231
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• 2018

A new procedure to produce poly(vinylidene fluoride)/boron nitride hybrid membrane is presented for application in membrane distillation (MD) process. The influence of hexagonal boron nitride (h-BN) incorporation on the performance of the polymeric membranes is studied through the present investigation. For this aim, h-BN nanopowders were successfully synthesized using the simple chemical vapor deposition (CVD) route and subsequent solvent treatments. The resulting h-BN nanosheets were blended with poly(vinylidene fluoride) (PVDF) solution. Then, the prepared composite solution was subjected to phase inversion process to obtain PVDF/h-BN hybrid membranes. Various examinations such as scanning electron microscopy (SEM), wettability, permeation flux, mechanical strength and liquid entry pressure (LEP) measurements are performed to evaluate the prepared membrane. Moreover, Air gap membrane distillation (AGMD) experiments were carried out to investigate the salt rejection performance and the durability of membranes. The results show that our hybrid PVDF/h-BN membrane presents higher water permeation flux (${\sim}18kg/m^2h$) compared to pristine PVDF membrane. In addition, the experimental data confirms that the prepared nanocomposite membrane is hydrophobic (water contact angle: ${\sim}103^{\circ}$), has a porous skin layer (>85%), as well competitive fouling resistance and operational durability. Furthermore, the total salt rejection efficiency was obtained for PVDF/h-BN membrane. The results prove that the novel PVDF/h-BN membrane can be easily synthesized and applied in MD process for salt rejection purposes.

• The Plant Pathology Journal
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• v.32 no.5
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• pp.431-440
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• 2016

In 2004, bacterial spot-causing xanthomonads (BSX) were reclassified into 4 species-Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri. Bacterial spot disease on pepper plant in Korea is known to be caused by both X. axonopodis pv. vesicatoria and X. vesicatoria. Here, we reidentified the pathogen causing bacterial spots on pepper plant based on the new classification. Accordingly, 72 pathogenic isolates were obtained from the lesions on pepper plants at 42 different locations. All isolates were negative for pectolytic activity. Five isolates were positive for amylolytic activity. All of the Korean pepper isolates had a 32 kDa-protein unique to X. euvesicatoria and had the same band pattern of the rpoB gene as that of X. euvesicatoria and X. perforans as indicated by PCR-restriction fragment length polymorphism analysis. A phylogenetic tree of 16S rDNA sequences showed that all of the Korean pepper plant isolates fit into the same group as did all the reference strains of X. euvesicatoria and X. perforans. A phylogenetic tree of the nucleotide sequences of 3 housekeeping genes-gapA, gyrB, and lepA showed that all of the Korean pepper plant isolates fit into the same group as did all of the references strains of X. euvesicatoria. Based on the phenotypic and genotypic characteristics, we identified the pathogen as X. euvesicatoria. Neither X. vesicatoria, the known pathogen of pepper bacterial spot, nor X. perforans, the known pathogen of tomato plant, was isolated. Thus, we suggest that the pathogen causing bacterial spot disease of pepper plants in Korea is X. euvesicatoria.

• Journal of Ginseng Research
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• v.46 no.4
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• pp.609-619
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• 2022

Obesity is a primary factor provoking various chronic disorders, including cardiovascular disease, diabetes, and cancer, and causes the death of 2.8 million individuals each year. Diet, physical activity, medications, and surgery are the main therapies for overweightness and obesity. During weight loss therapy, a decrease in energy stores activates appetite signaling pathways under the regulation of neuropeptides, including anorexigenic [corticotropin-releasing hormone, proopiomelanocortin (POMC), cholecystokinin (CCK), and cocaine- and amphetamine-regulated transcript] and orexigenic [agoutirelated protein (AgRP), neuropeptide Y (NPY), and melanin-concentrating hormone] neuropeptides, which increase food intake and lead to failure in attaining weight loss goals. Ginseng and ginsenosides reverse these signaling pathways by suppressing orexigenic neuropeptides (NPY and AgRP) and provoking anorexigenic neuropeptides (CCK and POMC), which prevent the increase in food intake. Moreover, the results of network pharmacology analysis have revealed that constituents of ginseng radix, including campesterol, beta-elemene, ginsenoside Rb1, biotin, and pantothenic acid, are highly correlated with neuropeptide genes that regulate energy balance and food intake, including ADIPOQ, NAMPT, UBL5, NUCB2, LEP, CCK, GAST, IGF1, RLN1, PENK, PDYN, and POMC. Based on previous studies and network pharmacology analysis data, ginseng and its compounds may be a potent source for obesity treatment by regulating neuropeptides associated with appetite.

• Journal of Animal Science and Technology
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• v.62 no.5
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• pp.614-627
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• 2020

During the course of this trial, our team assessed the influence of protease upon the growth performance, the nutrient digestibility, and the expression of growth-related genes and amino acid transporters within the liver, muscle, and small intestines of broilers. During the first step, our team allocated 600 broilers into four dietary treatments for a period of 35 days in order to measure the growth performance and nutrient digestibility of the broilers selected. The separate treatments contained 10 replicates (15 birds per replicate). The treatments were composed of: 1) CON, basal diet; 2) T1, basal diet + 0.03% protease; 3) T2, basal diet + 0.06% protease; and 4) T3, basal diet + 0.09% protease. Next, the broiler chick sample tissue was harvested from the CON and T3 groups in order to conduct gene expression analysis following the feeding trials the broilers underwent. Our team discovered that the broilers fed protease diets possessed increased body weight and an average daily gain, but conversely, had lower feed conversion ratios when their dietary protease levels increased from 0% to 0.09% (p < 0.05). Additionally, significant linear improvements were identified among the nutrient digestibility of dry matter, crude protein, energy, and amino acids within broilers supplied with protease diets when contrasted and compared with broilers supplied with the basal diet (p < 0.05). In addition, the gene expression of the genes IGF1, IGF2, GH, and LEP in the liver, and the genes MYOD1 and MYOG in the breast muscles, was significantly increased after broilers were fed with a protease diet as compared to broilers that subsisted on a basal diet (p < 0.05). Protease supplementation also raised the expression levels within these amino acid transporters: SCL6A19, SLC7A1, SLC7A7, SLC7A2, SLC7A6, SLC7A9, and SLC15A1, located in the small intestine, when compared to the basal diet (p < 0.05). Our results suggest that protease supplementation in their diet improved the growth performance of broilers via an increase in the expression growth-related genes within broiler liver and muscle tissue. In addition, protease supplementation enhanced broiler digestibility via the upregulation of amino acid transporter expression within the small intestine.