• Korean journal of food and cookery science
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• v.14 no.1
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• pp.91-96
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• 1998

Growth of acrospire length from germinated covered barley with 1.5∼2.0 times length of buds had the highest amylase activity for 9 days at 15$^{\circ}C$. When the extraction of malt was carried out at 50$^{\circ}C$ for 3.5 hr., total sugar, reducing sugar, sweetness determined by refractometer and amylase activity were the highest, and 2.33%, 1.61%, 3.4 brix(%), 28,332 units, respectively. The sikhe saccharificated at 60$^{\circ}C$ for 8 hr. showed total sugar content increased to 3.90∼9.27% in nonwaxy rice, 4.19∼11.91% in waxy rice, and reducing sugar-content increased 3.30∼7.61% in nonwaxy rice, 3.31∼9.11% in waxy rice. Also, brix was increased to 3.6∼10.8 brix (%) in nonwaxy rice, 3.6∼12.8 brix(%) in waxy .ice, as saccharification time increased. The amylase activity was decreased as saccharification time was increased. And pH was gradually decreased according to time increase, however, it changed little after 4 hr. Morphology of cooked rice kernel during saccharification for sikhe gradually enlarged the oval for hydrolyzed starch granule by increasing saccharification time.

• 한국해양학회지
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• v.20 no.3
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• pp.55-61
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• 1985

Two hundred suspended-matter samples were collected from the continental shelf off the southeast coast of Korea during September, 1981, March, 1982 and April 1983. Superficial bottom sediments on the shelf were also taken. Based on the alalyses of TSM distribution and concentration patterns, it is considered that finegrained suspended matters are restricted to nearshore-inner shelf showing a band or zone paralleling with coastal morphology. This fact suggests a limitation of "modern" fine grained sediments to a nearshore and inner shelf band. The sand deposits with the lower value of mud content (<5%) adjacent to the shelf break and on the outer shelf would probably be "relict" sediments (old beach sediments) deposited in response to a lower stand of sea level during the Pleistocene ice age. The transgression did little to alter the distribution of sand on the outer shelf in this particular study area. The progress of shore line was so rapid that a given locality was in the beach zone and subject to rapid longshore drift and extensive reworking only for a few years. Probably the most pronounced effect of the transgression was sorting of the sand, and at least partial winnowing out of the finer fractions.

• Journal of the Korean Society of Food Culture
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• v.16 no.2
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• pp.109-117
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• 2001

Judging from the studies carried out by Dr. Jo, Yong Jin on the Koreans' faces, Koreans divided into two constitutions according to their facial features and heritages. The one population is the Northern lineage whose ancestor migrated from Siberia in ice age. In order to survive in cold climate, they have developed a high level of metabolic heat production. Cold adaptation for preventing heat loss results in a reduction in the facial surface area with small eyes, nose and lips. The other population is the Southern lineage who is the descent of native in Korean peninsular. They have big eyes with double edged eyelids, broad nose and thick lips. It is generally believed that both genetic and environmetal factors influence eating behaviors. Although we can't recognized their heritage that may contribute to the metabolism and eating behavior, we commonly recognize their physiological heritage acceding to their facial features. In order to investigate the relationship among the size and shape of facial feature, the eating behavior, anthropometric measurement in female college students, the eating behaviors was measured during an instant-noodle lunch eaten in a laboratory setting at the ambient temperature of $23^{\circ}C$. The anterior surface area of left eye and length of right eye were positively correlated with the difference between the peak postprandial and the meal-start core temperature. The surface area of lower lip also negatively correlated with the meal-start core temperature and meal duration. In addition, the total lips' area was positively correlated with the difference between the peak postprandial and the meal-start core temperature and negatively correlated with the meal duration. However anthropometric measurements were not related with the size of facial features.

• Applied Microscopy
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• v.42 no.2
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• pp.111-114
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• 2012

The scanning electron microscopy is an ideal technique for examining plant surface at high resolution. Most hydrate samples, however, must be fix and dehydrate for observation in the scanning electron microscope. Because the microscopes operate under high vacuum, most specimens, especially biological samples, cannot withstand water removal by the vacuum system without morphological distortion. Cryo-techniques can observe in their original morphology and structure without various artifacts from conventional sample preparation. Rapid cooling is the method of choice for preparing plant samples for scanning electron microscopy in a defined physiological state. As one of cryo-technique, high-pressure freezing allows for fixation of native non-pretreated samples up to $200{\mu}M$ thick and 2 mm wide with minimal or no ice crystal damage for the freezing procedure. In this study, we could design to optimize structural preservation and imaging by comparing cryo-SEM and convention SEM preparation, and observe a fine, well preserved Arabidopsis stem's inner ultrastructure using HPF and cryo-SEM. These results would suggest a useful method of cryo-preparation and cryo-SEM for plant tissues, especially intratubule and vacuole rich structure.

• Journal of Embryo Transfer
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• v.33 no.2
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• pp.75-84
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• 2018

The cryopreservation has been extensively applied in many cells including spermatozoa (semen) during past several decades. Especially, the canine spermatozoa cryopreservation has contributed on generation of progeny of rare/genetically valuable dog breeds, genome resource banking and transportation of male germplasm at a distant place. However, severe and irreversible damages to the spermatozoa during cryopreservation procedures such as the thermal shock (cold shock), formation of intracellular ice crystals, osmotic shock, stress of cryoprotectants and generator of reactive oxygen species (ROS) have been addressed. According as a number of researches have been conducted to overcome these problems and to advance cryopreservation technique, several analytical methods have been employed to evaluate the quality of the fresh or cryopreserved canine spermatozoa in regards to the motility, morphology, integrity of membrane and DNA, mitochondrial activity, ROS generation, binding affinity to oocytes, in vitro fertilization potential and fertility potential by artificial insemination. Because the study designs with certain application of analytical methods are selective and varied depending on each experimental objective and laboratory condition, it is necessary to establish the normal reference data of the fresh or cryopreserved canine spermatozoa for each analytical method to monitor experimental procedure, to translate raw data and to discuss results. Here, we reviewed the recent articles to introduce various analytical methods for the canine spermatozoa as well as to establish the normal reference data for each analytical method in the fresh or cryopreserved canine spermatozoa, based on the results of the previous articles. We hope that this review contributes to the advancement of cryobiology in canine spermatozoa.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.179-186
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• 2003

Human embryonic stem (hES) cell lines have been derived from human blastocysts and are expected to have far-reaching applications in regenerative medicine. The objective of this study is to improve freezing method with less cryo-injuries and best survival rates in hES cells by comparing various vitrification conditions. For the vitrifications, ES cells are exposed to the 4 different cryoprotectants, ethylene glycol (EG), 1,2-propanediol (PROH), EG with dime-thylsulfoxide (DMSO) and EG with PROH. We compared to types of vehicles, such as open pulled straw (OPS) or electron microscopic cooper grids (EM grids). Thawed hES cells were dipped into sequentially holding media with 0.2 M sucrose for 1 min, 0.1 M sucrose for 5 min and holding media for 5 min twice and plated onto a fresh feeder layer. Survival rates of vitrified hES cells were assessed by counting of undifferentiated colonies. It shows high survival rates of hES cells frozen with EG and DMSO (60.8％), or EG and PROH(65.8％) on EM grids better than those of OPS, compared to those frozen with EG alone (2.4％) or PROH alone (0％) alone. The hES cells vitrified with EM grid showed relatively constant colony forming efficiency and survival rates, compared to those of unverified hES cells. The vitrified hES cells retained the normal morphology, alkaline phosphates activity, and the expression of SSEA-3 and 4. Through RT-PCR analysis showed Oct-4 gene expression was down-regulated and embryonic germ layer markers were up-regulated in the vitrified hES cells during spontaneous differentiation. These results show that vitrification method by using EM grid supplemented with EG and PROH in hES cells may be most efficient at present to minimize cyto-toxicity and cellular damage derived by ice crystal formation and furthermore may be employed for clinical application.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.63.3-63.3
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• 2019

Active asteroids are celestial bodies that distinctively have asteroid-like orbital elements but show comet-like activity. They exhibit the activities due to the sublimation of volatile ices, impacts with small objects or break-up by rapid rotations. As of 2019 February, 30 active asteroids are detected in the outer main belt (i.e., the semimajor axes a>2.5 au) while only 3 of them in the inner main belt (a<2.5 au), suggesting that sublimation of remaining icy volatiles can be one of the most fundamental mechanisms for the activities. A sudden activity of (6478) Gault was reported in early 2019. The asteroid was discovered in 1988 and has exhibited its inactive appearance until the end of last year. Soon after the report, we have conducted imaging observations using the Seoul National University Observatory 1.0-m telescope and the Korea Microlensing Telescope Network (KMTNet) to monitor the activity. The observed images showed a primary dust tail that consists of dust grains ejected early November in 2018. Later, another tail developed, indicating further dust ejection occurred around late December 2018. Our model simulation to reproduce the morphology of the dust cloud suggests that the slightly-curved primary dust tail results from a continuous dust ejection over weeks. The total mass of ejecta was estimated to XX kg (XX% of the asteroid mass). Such continuous dust ejection for the inner active asteroids was unexpected because ice might have already sublimated from subsurfaces of inner main belt. Based on our observational evidence, we will discuss how inner asteroids are activated and eject dust continuously.

• Korean Journal of Remote Sensing
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• v.34 no.2_1
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• pp.237-248
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• 2018

The vertical distribution of hydrometeor before precipitation near the cloud base has been analyzed using a scanning lidar, rawinsonde data, and Cloud-Resolving Storm Simulator (CReSS). This study mostly focuses on 13 Desember 2016 only. The typical synoptic pattern of lake-effect snowstorm induced easterly in the Yeongdong region. Clouds generated due to high temperature difference between 850 hPa and sea surface (SST) penentrated in the Yeongdong region along with northerly and northeasterly, which eventually resulted precipitation. The cloud base height before the precipitation changed from 750 m to 1,280 m, which was in agreement with that from ceilometer at Sokcho. However, ceilometer tended to detect the cloud base 50 m ~ 100 m below strong signal of lidar backscattering coefficient. As a result, the depolarization ratio increased vertically while the backscattering coefficient decreased about 1,010 m~1,200 m above the ground. Lidar signal might be interpreted to be attenuated with the penetration depth of the cloud layer with of nonspherical hydrometeor (snow, ice cloud). An increase in backscattering signal and a decrease in depolarization ratio occured in the layer of 800 to 1,010 m, probably being associated with an increase in non-spherical particles. There seemed to be a shallow liquid layer with a low depolarization ratio (<0.1) in the layer of 850~900 m. As the altitude increases in the 680 m~850 m, the backscattering coefficient and depolarization ratio increase at the same time. In this range of height, the maximum value (0.6) is displayed. Such a result can be inferred that the nonspherical hydrometeor are distributed by a low density. At this time, the depolarization ratio and the backscattering coefficient did not increase under observed melting layer of 680 m. The lidar has a disadvantage that it is difficult for its beam to penetrate deep into clouds due to attenuation problem. However it is promising to distinguish hydrometeor morphology by utilizing the depolarization ratio and the backscattering coefficient, since its vertical high resolution (2.5 m) enable us to analyze detailed cloud microphysics. It would contribute to understanding cloud microphysics of cold clouds and snowfall when remote sensings including lidar, radar, and in-situ measurements could be timely utilized altogether.

• Molecules and Cells
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• v.26 no.6
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• pp.566-575
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• 2008

Twenty-five chipmunk species occur in the world, of which only the Siberian chipmunk, Tamias sibiricus, inhabits Asia. To investigate mitochondrial cytochrome b sequence variations and population structure of the Siberian chipmunk in northeastern Asia, we examined mitochondrial cytochrome b sequences (1140 bp) from 3 countries. Analyses of 41 individuals from South Korea and 33 individuals from Russia and northeast China resulted in 37 haplotypes and 27 haplotypes, respectively. There were no shared haplotypes between South Korea and Russia - northeast China. Phylogenetic trees and network analysis showed 2 major maternal lineages for haplotypes, referred to as the S and R lineages. Haplotype grouping in each cluster was nearly coincident with its geographic affinity. In particular, 3 distinct groups were found that mostly clustered in the northern, central and southern parts of South Korea. Nucleotide diversity of the S lineage was twice that of lineage R. The divergence between S and R lineages was estimated to be 2.98-0.98 Myr. During the ice age, there may have been at least 2 refuges in South Korea and Russia - northeast China. The sequence variation between the S and R lineages was 11.3% (K2P), which is indicative of specific recognition in rodents. These results suggest that T. sibiricus from South Korea could be considered a separate species. However, additional information, such as details of distribution, nuclear genes data or morphology, is required to strengthen this hypothesis.

• Journal of Korean Dental Science
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• v.10 no.1
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• pp.10-21
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• 2017

Purpose: The purpose of this study was to investigate the electrochemical characteristics of nanotubular Ti-25Nb-xZr ternary alloys for dental implant materials. Materials and Methods: Ti-25Nb-xZr alloys with different Zr contents (0, 3, 7, and 15 wt.%) were manufactured using commercially pure titanium (CP-Ti), niobium (Nb), and zirconium (Zr) (99.95 wt.% purity). The alloys were prepared by arc melting in argon (Ar) atmosphere. The Ti-25Nb-xZr alloys were homogenized in Ar atmosphere at $1,000^{\circ}C$ for 12 hours followed by quenching into ice water. The microstructure of the Ti-25Nb-xZr alloys was examined by a field emission scanning electron microscope. The phases in the alloys were identified by an X-ray diffractometer. The chemical composition of the nanotube-formed surfaces was determined by energy-dispersive X-ray spectroscopy. Self-organized $TiO_2$ was prepared by electrochemical oxidation of the samples in a $1.0M\;H_3PO_4+0.8wt.%$ NaF electrolyte. The anodization potential was 30 V and time was 1 hour by DC supplier. Surface wettability was evaluated for both the metallographically polished and nanotube-formed surfaces using a contact-angle goniometer. The corrosion properties of the specimens were investigated using a 0.9 wt.% aqueous solution of NaCl at $36^{\circ}C{\pm}5^{\circ}C$ using a potentiodynamic polarization test. Result: Needle-like structure of Ti-25Nb-xZr alloys was transform to equiaxed structure as Zr content increased. Nanotube formed on Ti-25Nb-xZr alloys show two sizes of nanotube structure. The diameters of the large tubes decreased and small tubes increased as Zr content increased. The lower contact angles for nanotube formed Ti-25NbxZr alloys surfaces showed compare to non-nanotube formed surface. The corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface showed longer the passive regions compared to non-treatment surface. Conclusion: It is confirmed that corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface has longer passive region compared to without treatment surface.