• Biomaterials and Biomechanics in Bioengineering
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• 제2권2호
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• pp.97-109
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• 2015

A series of amphiphilic graft copolymers were synthesized by varying the number of graft chains and graft chain lengths. The polarity of the hydrophobic graft chain on the copolymers was varied their solution properties. The glass transition temperature of the copolymers was in the low-temperature region, because of the amorphous nature of poly (trimethylene carbonate) (PTMC). The surface morphology of the lyophilized colloid gel had a bundle structure, which was derived from the combination of poly(N-hydroxyethylacrylamide)( poly(HEAA)) and PTMC. The solution properties were evaluated using dynamic light scattering and fluorescence measurements. The particle size of the graft copolymers was about 30-300 nm. The graft copolymers with a higher number of repeating units attributed to the TMC (trimethylene carbonate) component and with a lower macromonomer ratio showed high thermal stability. The critical association concentration was estimated to be between $2.2{\times}10^{-3}$ and $8.9{\times}10^{-2}mg/mL$, using the pyrene-based fluorescence probe technique. These results showed that the hydrophobic chain of the graft copolymer having a long PTMC segment had a low polarity, dependent on the number of repeating units of TMC and the macromonomer composition ratio. These results demonstrated that a higher number of repeating units of TMC, with a lower macromonomer composition, was preferable for molecular encapsulation.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 2002년도 학술대회지
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• pp.509-521
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• 2002

'The Regional complex long-term program of restoration (reintroduction) of Primoryes ginseng population up to 2005' elaborated by Primorye governor administration, Regional Committee of Natural Resources and Russian Academy of Sciences operates in Russian Primorye. The Institute of Biology and Soil Science (IBSS) provides the scientific implementation of this program including the genetic analysis of extant ginseng populations, plant reproduction and offspring identification. According to our investigations, the genetic resource of P. ginseng in Primorye is represented by three populations of wild-growing ginseng and a few private plantations. The results obtained by RAPD allowed concluding that this resource is dispersed among the wild and cultivated ginseng sub-populations in such a way that each of sub-populations studied has to be represented in living plant collection as a stock material to maintain species genetic variability. The allozyme analyses also showed that the small sub-populations of natural ginseng are characterized by unique genetic diversity and, therefore, they all need to be represented in reintroduction centers. Additionally the allozyme analysis discovered that the Blue Mountain and Khasan populations possess the most genetic diversity. So, at least one more reproductive ginseng unit has to be created besides two already existing reintroduction centers representing the Sikhote-Alin and the Blue Mountain populations.

• 한국육종학회지
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• 제43권5호
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• pp.479-489
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• 2011

Gluten is the main functional component of wheat, and is the main source of the viscoelastic properties in a dough. One of the gluten group is glutenin, which is composed of high molecular weight (HMW) and low molecular weight (LMW) subunits. The HMW glutenin subunits (HMW-GS) have been shown to play a crucial role in determining the processing properties of the grain. They are encoded by the Glu-1 loci located on the long arms of homeologous group one chromosomes, with each locus comprising two genes encoding x- and y-type subunits. The presence of certain HMW subunits is positively correlated with good bread-making quality. The highly conserved N- and C- terminal contaning cystein residues which form interand intra-chain disulphide bonds. This inter chain disulphide bonds stabilize the glutenin polymers. In contrast, the repetitive domains that comprise the central part of the HMW-GS are responsible for the elastic properties due to extensive arrays of interchain hydrogen bonds. In this review, we discuss HMW-GS, HMW-GS structure and gluten elasticity, relationship between HMW-GS and bread wheat quality and genetic engineering of the HMW-GS.

• 한국축산식품학회지
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• 제38권6호
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• pp.1237-1245
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• 2018

In this study, the contamination levels of hygienic indicators and foodborne pathogens in retail meat products were investigated in relation to the various market factors including processing temperature, processing area, and market type. Ground beef samples (n=80) were purchased from 40 meat markets and investigated for microbiological quality. Beefs processed below $20^{\circ}C$ had significantly lower numbers of total coliforms (TC) than these processed over $20^{\circ}C$ (2.01 vs. 2.79 log CFU/g; p<0.05). Interestingly, separation of processing area did not affect the contamination levels. Remarkably, the contamination levels of hygienic indicator differ among market types, indicating that not only processing condition but distribution structure that is directly related with storage period could affect the final microbiological loads of the meat products. In addition, the prevalences of Listeria monocytogenes (a psychrotroph), Enterococcus faecium, and Enterococcus faecalis were 7.5% (6/80), 10.0% (8/80), and 20.0% (16/80), respectively, which is irrelevant to market factors except meat products from wholesale markets where no L. monocytogenes were found among 30 samples. The results of this study indicate that the contamination level of hygiene indicator and foodborne pathogens in retail beef is more related with processing temperature and storage period than other environmental factors.

• Advances in nano research
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• 제10권1호
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• pp.59-69
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• 2021

Electrospinning is a cost-effective and versatile method for producing submicron fibers. Although this method is relatively simple, at the theoretical level the interactions between process parameters and their influence on the fiber morphology are not yet fully understood. In this paper, the aim was finding optimal electrospinning parameters in order to obtain the smallest fiber diameter by using Taguchi's methodology. The nanofibers produced by electrospinning a solution of Thermoplastic Polyurethane (TPU) in Dimethylformamide (DMF). Polymer concentration and process parameters were considered as the effective factors. Taguchi's L9 orthogonal design (4 parameters, 3 levels) was applied to the experiential design. Optimal electrospinning conditions were determined using the signal-to-noise (S/N) ratio with Minitab 17 software. The morphology of the nanofibers was studied by a Scanning Electron Microscope (SEM). Thereafter, a tensile tester machine was used to assess mechanical properties of nanofibrous scaffolds. The analysis of DoE experiments showed that TPU concentration was the most significant parameter. An optimum combination to reach smallest diameters was yielded at 12 wt% polymer concentration, 16 kV of the supply voltage, 0.1 ml/h feed rate and 15 cm tip-to-distance. An empirical model was extracted and verified using confirmation test. The average diameter of nanofibers at the optimum conditions was in the range of 242.10 to 257.92 nm at a confidence level 95% which was in close agreement with the predicted value by the Taguchi technique. Also, the mechanical properties increased with decreasing fibers diameter. This study demonstrated Taguchi method was successfully applied to the optimization of electrospinning conditions for TPU nanofibers and the presented scaffold can mimic the structure of Extracellular Matrix (ECM).

• Journal of Animal Science and Technology
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• 제63권2호
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• pp.339-353
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• 2021

This study aimed to assess the causality of different climate variables on the production of whole crop maize (Zea mays L.; WCM) in the central inland region of the Korea. Furthermore, the effect of these climate variables was also determined by looking at direct and indirect pathways during the stages before and after silking. The WCM metadata (n = 640) were collected from the Rural Development Administration's reports of new variety adaptability from 1985-2011 (27 years). The climate data was collected based on year and location from the Korean Meteorology Administration's weather information system. Causality, in this study, was defined by various cause-and-effect relationships between climatic factors, such as temperature, rainfall amount, sunshine duration, wind speed and relative humidity in the seeding to silking stage and the silking to harvesting stage. All climate variables except wind speed were different before and after the silking stage, which indicates the silking occurred during the period when the Korean season changed from spring to summer. Therefore, the structure of causality was constructed by taking account of the climate variables that were divided by the silking stage. In particular, the indirect effect of rainfall through the appropriate temperature range was different before and after the silking stage. The damage caused by heat-humidity was having effect before the silking stage while the damage caused by night-heat was not affecting WCM production. There was a large variation in soil surface temperature and rainfall before and after the silking stage. Over 350 mm of rainfall affected dry matter yield (DMY) when soil surface temperatures were less than 22℃ before the silking stage. Over 900 mm of rainfall also affected DMY when soil surface temperatures were over 27℃ after the silking stage. For the longitudinal effects of soil surface temperature and rainfall amount, less than 22℃ soil surface temperature and over 300 mm of rainfall before the silking stage affected yield through over 26℃ soil surface temperature and less than 900 mm rainfall after the silking stage, respectively.

• 한국축산식품학회지
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• 제43권4호
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• pp.712-720
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• 2023

Osteoporosis is a growing global health concern primarily associated with decreased estrogen in postmenopausal women. Recently, some strains of probiotics were examined for potential anti-osteoporotic effects. This study intended to evaluate the impacts of Lactiplantibacillus plantarum MGE 3038 strain (MGE 3038) in ovariectomized rats. For this purpose, twelve weeks old female Wistar rats (n=21; 250-300 g) were divided into 3 groups; ovariectomy (OVX) group, OVX/MGE 3038 group and Sham group (control). In these groups; two went through respective OVX and one had daily MGE 3038 administration through oral gavage. Prior to 16 weeks after OVX, we collected blood samples and extracted the tibiae. We scanned the extracted tibiae by in-vivo micro-computed tomography (micro-CT) and evaluated pathology by hematoxylin and eosin (H&E) and Masson's trichrome staining. The serum levels of C-telopeptide of type I collagen (CTX), osteocalcin (OC), and the receptor activator of nuclear factor-κB ligand (RANKL) were examined. The OVX/MGE 3038 group showed increases in bone mineral density, trabecular bone volume, trabecular number, and trabecular thickness (Tb.Th), and a decrease in trabecular spacing than the OVX group. However, OVX/MGE 3038 group and control group were measurably comparable in Tb.Th. Micro-CT, H&E, and Masson's trichrome findings exhibited increased preservation and maintenance of trabecular bone structure in the OVX/MGE 3038 group in comparison to the OVX group. In serum, the levels of CTX, OC and RANKL were significantly different between the OVX and OVX/MGE 3038 groups. Taken together, L. plantarum MGE 3038 could be helpful for the treatment of osteoporosis.

• 한국가스학회지
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• 제27권3호
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• pp.19-26
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• 2023

수소는 화석연료를 대체할 수 있는 COx-free 에너지원으로 사용량은 지속적으로 증가할 것이다. 수소는 단위 질량당 에너지 함량이 높으나, 낮은 저장 밀도와 장기 저장의 어려움으로 저장 및 운송에 한계가 존재한다. 반면, 암모니아는 단위 부피당 저장용량이 크고, 비교적 액화가 용이하여 대용량 수소를 저장 및 운송할 수 있는 수소 운반체로 주목받고 있다. 암모니아 분해를 통한 수소 생산 반응은 흡열반응으로 공정의 효율성 및 경제성을 위해 저온 활성이 우수한 촉매 개발이 요구된다. 본 연구에서는 활성금속 Ni의 고분산 담지를 위해 넓은 비표면적의 제올라이트를 지지체로 사용하였으며, 제올라이트 종류(5A, NaY, ZSM5)에 따른 특성(기공구조, 양이온, Si/Al-비)이 촉매 활성 및 반응 특성에 미치는 영향을 확인하였다. 5A 제올라이트는 표면, 기공, 구조체 내에 Ni 을 고분산 담지를 가능하게 하였으며, 낮은 Si/Al-비로 인한 풍부한 산점은 암모니아 흡착을 증가시켰다. 또한, 지지체에 포함된 Na과 Ca 양이온으로 인한 중간-염기점은 질소 탈착속도를 향상시켰다. 따라서, 15wt%Ni/5A 촉매는 강한 금속-지지체 상호작용과 중간-염기점을 통한 질소 탈착 속도 향상으로 가장 우수한 암모니아 전환율과 높은 수소 생성율 23.5 mmol/g_cat·min (30,000 mL/g_cat·h, 600 ℃)을 보였다.

• 공업화학
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• 제9권6호
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• pp.822-828
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• 1998

$^1H$ NMR gradient spin echo법을 이용하여 polyoxyethylene dodecyl ether[$C_{12}H_{25}(OCH_2CH_2)nOH$] 수용액에서 미셀 형성과정에 대한 것을 비교검토 하였다. 여기서 n=5($C_{12}EO_5$) 및 n=8($C_{12}EO_8$)인 비이온성 계면활성제를 사용하였으며 등방성상의 영역범위에서의 자기확산 계수는 일정온도에서 농도변화에 따른 pulsed field gradient법을 사용하여 측정하였고, 또한 여러 프로톤의 시그날에 대한 피크폭(line width)을 추적하여 액정 특성에 대한 것을 검토하였다. 알킬사슬의 메틸렌 시그날의 넓혀짐은 $C_{12}EO_5-$물 계에서는 핵사고날 액정상의 근접될 때 관찰되었지만 $C_{12}EO_8-$물 계에서는 넓혀짐이 보다 작게 관찰되었다. 낮은 온도에서 농도가 증가함에 따라 $C_{12}EO_5$에서는 막대형 미셀이 형성되지만 $C_{12}EO_8$에서는 전 농도 범위에서 작은 미셀로 이루워 진다. 계면활성제의 자기확산계수는 서서히 증가하다가 극소점에 이르러서는 농도가 증가함에 따라 급격히 감소한다. 극소점의 위치는 온도가 담점에 이르렀을 때 낮은 농도에서 나타나고 이 계에서는 두 개의 등방성 상으로 분리된다. 피크폭 연구에서 피크폭의 넓어짐은 $C_{12}EO_5$에서는 온도가 증가되었을 때 온도의 차이로 형성된다. 그 결과 담점에 이르러 계면활성제의 회합체가 커지는 것으로 생각한다. 이 회합체가 담점에 이르러 한정된 모양을 갖는 것은 아니다. $C_{12}EO_8$에서는 미셀들이 온도의 증가에 영향을 받지 않고 미셀형성이 불확실하다. 에틸렌옥사이드 일부분의 메틸렌 시그날은 일관되게 좁게 나타났다. 회합에 있어서 이들은 알킬사슬 메틸렌보다 작은 질서로 나타내었다. 회합의 크기나 모양에 있어서 여러 변화성은 상 변화에 따라 등방성과 액정상의 안정성 범위가 정하여 진다. 회합체 크기와 상 구조는 여러 온도와 농도 변화에서 분자의 효과적 모형을 고려하여 정성적인 결과에 따른다.

• 한국산림과학회지
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• 제94권6호
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• pp.410-419
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• 2005

상록활엽수림의 지속적 보전을 도모하기 위하여 전남 진도의 여귀산에서 상록활엽수림을 대상으로 식생조사를 실시하였다. 주요 상록수종에 대하여 흉고직경분포와 개체군분포상황을 파악하였으며, 수종의 중요치를 사용하여 cluster 분석에 의하여 군집을 분류하였다. 군집별로 종다양도, 균재도, 종상관 등을 산출하였으며, CCA분석에 의하여 군집과 토양환경인자간의 연관관계를 파악하였다. Cluster 분석에 의하면 여귀산의 상록활엽수림은 동백나무군집군과 붉가시나무군집군으로 분류되었다. 이는 다시 동백나무-상록활엽수군집, 동백나무-참식나무군집, 동백나무-낙엽활엽수군집, 붉가시나무-동백나무군집, 붉가시나무군집의 5개 군집으로 세분되었다. 상록활엽수 수종 중에서는 동백나무, 붉가시나무, 참식나무, 후박나무, 붓순나무, 광나무 등이 우점종으로 나타났고, 낙엽활엽수 수종 중에서는 때죽나무, 비목나무, 산딸나무, 산벚나무, 자귀나무, 상수리나무 등이 생육하고 있었다. 각 군집의 종다양도는 붉가시나무-동백나무군집이 종다양도가 0.8231로 가장 높게 나타났으며 붉가시나무군집(0.8135), 동백나무-낙엽활엽수군집(0.7931), 동백나무-상록활엽수군집(0.7674), 동백나무-참식나무군집(0.6164) 순이었다. 여귀산의 주요 상록수종은 2 cm~10 cm의 직경급이 전체의 약 80%를 차지하는 것으로 나타났으며 DBH 5 cm 이하의 동백나무가 전 지역에 걸쳐 괴상으로 분포하고 DBH가 증가함에 따라 임의분포하는 경향을 보였다. 한편 DBH 15 cm 이상에서는 붉가시나무가 참식나무, 후박나무 등에 비해 집중되는 경향을 보였다. 동백나무와 붉가시나무, 붓순나무, 산딸나무 사이에는 유의적인 부의 상관관계를 보였지만, 참식나무와는 유의적인 정의 상관관계를 나타냈다. 붉가시나무는 참식나무, 후박나무와는 유의적인 부의 상관관계를 나타냈고, 붓순나무와는 유의적인 정의 상관관계를 나타냈으며 참식나무는 산딸나무와 부의 상관관계를 보였다. 조사지의 토양 pH는 4.04~5.16이었고, 유기물함량은 3.15~9.21%, 유효인산함량은16.1~37.1 ppm, 양이온치환용량은 7.6~11.5 me/100 g이었다. CCA분석에 의하여 5개 군집 및 주요 수종의 분포를 살펴본 결과 토양유기물함량과 양이온치환용량이 높고 토양 산도가 낮아질수록 동백나무가 우점종으로 생육하면서 점차 참식나무, 붉가시나무의 혼효군집으로 발달하는 경향을 나타내었다.