• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.123-131
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• 2009

Purpose: We tested a sample of nuclear medicine workers at Korean healthcare institutions for internal contamination with radioactive isotopes, measuring concentrations and evaluating doses of individual exposure. Materials and Methods: The detection and measurement was performed on urine samples collected from 25 nuclear medicine workers at three large hospitals located in Seoul. Urine samples were collected once a week, 100~200 mL samples were gathered up to 6~10 times weekly. A high-purity germanium detector was used to measure gamma radiations in urine samples for the presence of radioactive isotopes. Based on the detection results, we estimated the amounts of intake and committed effective doses using IMBA software. In cases where committed effective doses could not be adequately evaluated with IMBA software, we estimated individual committed effective doses for radionuclides with a very short half life such as $^{99m}Tc$ and $^{123}I$, using the methods recommended by International Atomic Energy Agency. Results: Radionuclides detected through the analysis of urine samples included $^{99m}Tc$, $^{123}I$, $^{131}I$ and $^{201}Tl$, as well as $^{18}F$, a nuclide used in Positron Emission Tomography examinations. The committed effective doses, calculated based on the radionuclide concentrations in urine samples, ranged from 0 to 5 mSv, but were, in the majority of cases, less than 1 mSv. The committed effective dose exceeded 1 mSv in three of the samples, and all three were workers directly handling radioactive sources. No nurses were found to have a committed effective dose in excess of 1 mSv. Conclusions: To improve the accuracy of results, it may be necessary to conduct a long-term study, performed over a time span wide enough to allow the clear determination of the influence of seasonal factors. A larger sample should also help increase the reliability of results. However, as most Korean nuclear medicine workers are currently not necessary to monitored routinely for internal contamination with radionuclides. Notwithstanding, a continuous effort is recommended to reduce any unnecessary exposure to radioactive substances, even if in inconsequential amounts, by regularly surveying workplace environments and frequently monitoring atmospheric concentrations of radionuclides.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.235-249
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• 2011

A new form of I-type PSC bridge girder, which has hole in the web, is proposed in this paper. Three different concepts were combined and implemented in the design. First of all, a girder was precast at a manufacturing plant as divided pieces and assembled at the construction site using post-tensioning method, and the construction period at the site will be reduced dramatically. In this way, the quality of concrete can be assured at the manufacturing factory and concrete curing can be well controlled, and the spliced girder segments can be moved to the construction site without a transportation problem. Secondly, a numerous number of holes was made in the web of the girder. This reduces the self-weight of the girder. But more important thing related to the holes is that about half of the total anchorages can be moved from the girder ends into individual holes. The magnitude of negative moment developed at girder ends will be reduced. Also, since the longitudinal compressive stresses are reduced at ends, thick end diaphragm is not necessary. Thirdly, Prestressing force was introduced into the member through multiple stages. This concept of multi-stage prestressing method overcomes the prestressing force limit restrained by the allowable stresses at each loading stage, and maximizes the magnitude of applicable prestressing force. It makes the girder longer and shallower. Two 50 meter long full scale girders were fabricated and tested. One of them was non-spliced, or monolithic girder, made as one piece from the beginning, and the other one was assembled using post-tensioning method from five pieces of segments. It was found from the result that monolithic and spliced girder show similar load-deflection relationships and crack patterns. Girders satisfied specific girder design specification in flexural strength, deflection, and live load deflection control limit. Both spliced and monolithic holed web post-tensioned girders can be used to achieve span lengths of more than 50m with the girder height of 2 m.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.1
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• pp.23-34
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• 2009

Objectives: Mesenchymal stem cells (MSC) comprise a promising tool for cellular therapy. It is known that long-term in vitro culture of human bone marrow and adipose tissue derived-MSCs lead to a reduction of life span and a change of stem-like characters. The aim of our study was to examine whether stem cell properties of human umbilical cord-derived stem cells (HUC) could be affected by in vitro expansion. Methods: HUC were isolated from human umbilical cord and cultured for 10 passages in vitro. Morphology and population doubling time (PDT) were investigated, and changes of stem cell properties were examined using RT-PCR and immunocytochemistry during serial subcultures. Results: Morphology and PDT of HUC began to change slightly from the 7th passage (p7). Expression level of nestin and vimentin mRNAs increased along with the culture period from p4 until p10. In contrast, expression level of SCF mRNA decreased during the same culture period. Expression level of Oct-4 and HNF-4${\alpha}$ mRNAs was not significantly changed throughout the culture period until p10. Expression level of BMP-4, FGF-5, NCAM and HLA-ABC mRNAs appeared to increase as the culture continued, however, the difference was not significant. Immunocytochemical studies showed that HUC at p3, p6 and p9 positively were stained with antibodies against SSEA-3 and SSEA-4 proteins. Interestingly, staining intensity of HUC for ICAM-1 and HLA-ABC gradually increased throughout the culture period. Intensity against thy-1 and fibronectin antibodies increased at p9 while that against TRA-1-60 and VCAM-1 antibodies began to decrease at p6 until p9. Conclusions: These results suggest that HUC change some of their stem cell characteristics during in vitro culture. Development of culture system might be needed for the maintenance of characteristics.

• Korean Journal of Environmental Biology
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• v.34 no.2
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• pp.63-72
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• 2016

The objective of this study was to identify the life form characteristics, naturalized degree and introduction period of naturalized plants on upland fields in South Korea. The survey sites were selected in 222 upland fields over 9 provinces where are relatively dry soil conditions and are disturbed continuously by farming practices. It seemed that these uplands maintain good condition for the invasion and settlement of alien plants. Field surveys were carried out twice from May to June and from August to September in 2013. The vascular plants of the upland fields were listed into 539 taxa which contain 103 families, 320 genera, 448 species, 2 subspecies, 74 varieties and 15 forms. Ninety nine taxa were naturalized plants composed of 23 families, 64 genera, 91 species and 8 varieties. The urbanization index and naturalized index is 30.65% and 18.37%, respectively. Among total 99 naturalized plants, Compositae (30 taxa) was the most dominant family, and followed by Gramineae (14 taxa). On the basis of dormancy form, 78 taxa were belong to Th (Therophyte). In radicoid form, $R_5$ plants (86 taxa) and $R_3$ plants (14 taxa) were dominantly distributed. In disseminule form, $D_4$ including 63 taxa and $D_2$ containing 26 taxa were dominant. On the basis of growth form, erect form (e) containing 26 taxa was dominant. In conclusion, life form spectrum was $Th-R_5-D_4-e$ type. According to life form analysis, naturalized degree and introduction period, alien plants with unique characteristics may have high ability to settle and spread nationwide after inflow into South Korea. It needs further to observe some plant species with or without ecological features such as widely disseminated seeds by wind or water, high seed productivity, long life-span seeds, high germination rate of seeds, or non-dormant germinable seed.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.191-204
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• 1994

Due to its topographic complexities and various climatical condition, Korea exhibits diverse forest types. Dominant tree species in this zone are Quercus spp., Betula spp., Zelkova spp., Fraxinus spp., Pinus densiflora, Pinus koraiensis, and Pinus thunbergii ete. Genetic conservation in forest species in Korea there are three ways ; one is in situ, other is ex situ and third is in-facility conservation. In situ conservation include that are the present status of conservation of rare and endangered flora and ecosystem, the reserved forest, the national and provincial park, and the gene pool of natural forests. Ex situ conservation means to be established the new forest from in situ forest stands, progeny and provenance test populations, seed orchard and clone banks, and gene conservation in-facility. As a tool for low temperature storage, several aspects on in vitro system were studied ; (1) establishment of in vitro cultures from juvenile and/or rejuvenated tissues, (2) induction of multiple shoots from the individual micropropagules, (3) elongation of the proliferated shoots. Studies on cold storage for short-and long-term maintenance of in vitro cultures under $4^{\circ}C$ in the refrigerator were conducted. For the cryopreservation at $-196^{\circ}C$, various factors affecting survivability of the plant materials are being examined. The necessity of gene conservation of forest trees is enlarged not only to increase the adaptability for various environments but also to gain the breeding materials in the future. For effective gene conservation of forest trees, I would like to suggest followings ; 1. Forest stands reserved for other than the gene conservation purposes such as national parks should be investigated by botanical and gene-ecological studies for selecting bio-diversity and gene conservation stands. 2. Reserved forest for gene pool should be extented both economically important tree spp. and non-economical species. 3. Reserved forest for progeny test and clone bank should be systematically investigated for the use of Ex situ forest gene conservation. 4. We have to find out a new methodology of genetic analysis determining the proper and effective size of subpopulation for in situ gene conservation. 5. We should develop a new tree breeding systems for successful gene conservation and utilization of the genetic resources. 6. New method of in-facility gene conservation using advanced genetic engineering should be developed to save time and economic resources. 7. For the conservation of species with short-life span of seed or shortage of knowledge of seed physiology, tissue culture techniques will be played a great role for gene conservation of those species. 8. It is are very useful conservation not only of genes but of genotypes which were selected already by breeding program. 9. Institutional and administrative arrangements including legistlation must be necessarily taken for gene conservation of forest trees. 10. It is national problems for conservation of forest resources which have been rapidly destroyed because of degenerating environmental condition and of inexperienced management system of bio-diversity and gene conservation. 11. In order to international cooperation for exchanging data of bio-diversity and gene conservation, we should connect to international net works as soon as possible.

• Journal of fish pathology
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• v.18 no.1
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• pp.19-28
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• 2005

Scuticociliatosis has badly settled one of most damaging diseases during the seedling production process of olive flounder. Paralichthys olivaceus in Korea. We isolated a new type of Scuticociliate from flounder. The parasite metamorphoses to ciliate and cyst phases with each other by environmental changes and survive for a relatively long span. The ciliate was measured average 41.8 ${\mu}m$ in length and 21.0 ${\mu}m$ in width, and cyst was 17.0 ${\mu}m$ and 13.5 ${\mu}m$, respectively. Nutritional condition was determined as a major parameter of metamorphosing between ciliate and cyst stages. The ciliate transforms to a cyst stage because of food shortage, and the cyst returns to a ciliate stage with a favorite environmental condition and shows active growth and reproduction. The ciliate multiplied at the maximal density of $2.9 {\times} 10^5 {m\ell}^{-1}$cells in vitro cultivation at $15 ^{\circ}C$temperature using MS BHI medium and bacterial food sources. The ciliate could be proliferated at a 2.5 to $30 ^ \circ}C$ temperature range, pH 6 to 9, and 1 to 55 ppt salinity. Particularly, it survived over one week at $0 ^{\circ}C$temperature showing a high resistance against unfavorable environmental conditions. And the cyst survived for 320 days in the condition of $5 ^{\circ}C$with no feeding, but its survival period was markedly shortened in higher temperature conditions. The chemotherapeutants (formalin and hydrogen peroxide) were clarified as effective chemicals against the ciliate during in vitro trials, but the effect of therapeutants differed in proportion, depending upon the density and the bathing time of chemical compounds.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.27-36
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• 1984

It was previously reported that red ginseng extract inhibited carcinogenesis by urethan, DMBA and aflatoxin $B_1E (Cancer Detection and Prevention, 6: 515-525, 1983). In an attempt to investigate the mechanism of the anticarcinogenic effect of ginseng, we assayed natural killer (N.K) activity in mice treated with urethan and benzo(a)pyrene. In our experiment newly born Swiss Webster mice, less than 24 hrs. old, were given a single subcutaneous injection of lmg of ure-than and 40ug of benzo(a)pyrene. The mice had been administered with ginseng since weaning, and sacrificed at various intervals. Major organs were examined both, with the naked eye and microscopically. N.K. activity of spleen cells was analyzed in a 12-hour $^{51}Cr^-release$ assay against YAC-1 cells. Administration of ginseng resulted in an increase of N.K. activity by $18\%$ at 4 weeks, $20\%$ (P < 0.05) at 6, $29\%$ (P < 0.05) at 12, and $13\%$ at 24 following a single injection of urethan. At the same time, significantly lower incidences of lung adenoma were noted at 6 weeks $(50\%)$ and 12 weeks $(27\%)$ following the administration of ginseng to urethan-injected mice. This result indicates that the enhancement of N.K. activity by ginseng makes a contribution to its anticarcinogenic effect. On the hand, N.K. activity was suppressed by benzo(a)pyrene during the time span of this experiment and it almost returned to the level of controls following the adminsitration of ginseng. However, the lung adenoma induced by benzo(a)pyrene began to occur at 48 weeks in which N.K. activity had naturally declined to a very low level in all experimental mice, and administration of ginseng did not decrease the incidence. In explanation of this result, we might propose that the recovery of the N.K. activity by ginseng had little effect on the incidence of lung adenoma because of the long latent period of carcinogenesis by benzo(a)pyrene. In conclusion, these results suggest that the anticarcinogenic effect of ginseng in urethan-treated mice may be related to the augmentation of N.K. activity.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.191-198
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• 2009

Statement of problem: Ceramics have been important materials for the restoration of teeth. The demands of patients for tooth-colored restorations and the availability of various dental ceramics has driven the increased use of new types of dental ceramic materials. Improved physical properties of theses materials have expanded its use even in posterior crowns and fixed partial dentures. However, ceramic still has limitation such as low loading capability. This is critical for long-span bridge, because bridge is more subject to tensile force. Purpose: The wire reinforced ceramic was designed to increase the fracture resistance of ceramic restoration. The purpose of this study was to evaluate the fracture resistance of wire reinforced ceramic. Material and methods: Heat pressed ceramic(ingot No.200 : IPS Empress 2, Ivoclar Vivadent, Liechtenstein) and Ni-Cr wire(Alfa Aesar, Johnson Matthey Company, USA) of 0.41 mm diameter were used in this study. Five groups of twelve uniform sized ceramic specimens(width 4 mm, thickness 2 mm, length 15 mm) were fabricated. Each group had different wire arrangement. Wireless ceramic was used as control group. The experimental groups were divided according to wire number and position. One, two and three strands of wires were positioned on the longitudinal axis of specimen. In another experimental group, three strands of wires positioned on the longitudinal axis and five strands of wires positioned on the transverse axis. Three-point bending test was done with universal testing machine(Z020, Zwick, Germany) to compare the flexural modulus, flexural strength, strain at fracture and fracture toughness of each group. Fractured ceramic specimens were cross-sectioned with caborundum disc and grinded with sandpaper to observe interface between ceramic and Ni-Cr wire. The interface between ceramic and Ni-Cr wire was analyzed with scanning electron microscope(JSM-6360, JEOL, Japan) under platinum coating. Results: The results obtained were as follows: 1. The average and standard deviation in flexural modulus, flexural strength and fracture toughness showed no statistical differences between control and experimental groups. However, strain was significantly increased in wire inserted ceramics(P<.001). 2. Control group showed wedge fracture aspects across specimen, while experimental groups showed cracks across specimen. 3. Scanning electron microscopic image of cross-sectioned and longitudinally-sectioned specimens showed no gap at the interface between ceramic and Ni-Cr wire. Conclusion: The results of this study showed that wire inserted ceramics have a high strain characteristic. However, wire inserted ceramics was not enough to use at posterior area of mouth in relation to flexural modulus and flexural strength. Therefore, we need further studies.

• Journal of Life Science
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• v.29 no.6
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• pp.747-753
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• 2019

Cognitive decline is characterized by reduced long-/short-term memory and attention span, and increased depression and anxiety. Such decline is associated with various degenerative brain disorders, especially Alzheimer's disease (AD) and Parkinson's disease (PD). The increases in elderly populations suffering from cognitive decline create social problems and impose economic burdens, and also pose safety threats; all of these problems have been extensively researched over the past several decades. Possible causes of cognitive decline include metabolic and hormone imbalance, infection, medication abuse, and neuronal changes associated with aging. However, no treatment for cognitive decline is available. In neurodegenerative diseases, changes in the gut microbiota and gut metabolites can alter molecular expression and neurobehavioral symptoms. Changes in the gut microbiota affect memory loss in AD via the downregulation of NMDA receptor expression and increased glutamate levels. Furthermore, the use of probiotics resulted in neurological improvement in an AD model. PD and gut microbiota dysbiosis are linked directly. This interrelationship affected the development of constipation, a secondary symptom in PD. In a PD model, the administration of probiotics prevented neuron death by increasing butyrate levels. Dysfunction of the blood-brain barrier (BBB) has been identified in AD and PD. Increased BBB permeability is also associated with gut microbiota dysbiosis, which led to the destruction of microtubules via systemic inflammation. Notably, metabolites of the gut microbiota may trigger either the development or attenuation of neurodegenerative disease. Here, we discuss the correlation between cognitive decline and the gut microbiota.

• MISULJARYO - National Museum of Korea Art Journal
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• v.96
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• pp.89-122
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• 2019

In this paper, I argue that the Handscroll of a Sightseeing Trip to the Hangang and Imjingang Rivers by Jeong Su-yeong (1743~1831, pseudonym: Jiwujae) is a record of his private journeys to several places on the outskirts of Hanyang (present-day Seoul) and that it successfully embodies the painter's subjective perspective while boating on these rivers and going on outings to nearby mountains. Around 1796, Jeong Su-yeong traveled to different places and documented his travels in this 16-meter-long handscroll. Several leaves of paper, each of which depicts a separate landscape, are pieced together to create this long handscroll. This indicates that the Handscroll of a Sightseeing Trip to the Hangang and Imjingang Rivers reflected the painter's personal subjective experiences as he went along his journey rather than simply depicts travel destinations. The Handscroll of a Sightseeing Trip to the Hangang and Imjingang Rivers features two types of travel: boating and mountain outings on foot. Traveling by boat takes up a large portion of the handscroll, which illustrates the channels of the Hangang and Imjingang Rivers. Mountain outings correspond to the sections describing the regions around Bukhansan, Gwanaksan, and Dobongsan Mountains. Jeong Su-yeong traveled to this wide span of places not just once, but several times. The fact that the Hangang River system are not presented in accordance with their actual locations shows that they were illustrated at different points. After visiting the riversides of the Hangang and Namhangang Rivers twice, Jeong Su-yeong delineated them in fourteen scenes. Among them, the first eight illustrate Jeong's initial trip by boat, while the other six scenes are vistas from his second trip. These fourteen scenes occupy half of this handscroll, indicating that the regions near the Hangang River are painted most frequently. The scenes of Jeong Su-yeong's first boating trip to the system of the Hangang River portray the landscapes that he personally witnessed rather than famous scenes. Some of the eight scenic views of Yeoju, including Yongmunsan Mountain, Cheongsimru Pavilion, and Silleuksa Temple, are included in this handscroll. However, Jeong noted spots that were not often painted and depicted them using an eye-level perspective uncommon for illustrating famous scenic locations. The scenes of Jeong's second boating trip include his friend's villa and a meeting with companions. Moreover, Cheongsimru Pavilion and Silleuksa Temple, which are depicted in the first boating trip, are illustrated again from different perspectives and in unique compositions. Jeong Su-yeong examined the same locations several times from different angles. A sense of realism is demonstrated in the scenes of Jeong's first and second boating trips to the channels of the Hangang River, which depict actual roads. Furthermore, viewers can easily follow the level gaze of Jeong from the boat. The scenes depicting the Imjingang River begin from spots near the Yeongpyeongcheon and Hantangang Rivers and end with places along the waterways of the Imjingang River. Here, diverse perspectives were applied, which is characteristic of Imjingang River scenes. Jeong Su-yeong employed a bird's-eye perspective to illustrate the flow of a waterway starting from the Yeongpyeongcheon River. He also used an eye-level perspective to highlight the rocks of Baegundam Pool. Thus, depending on what he wished to emphasize, Jeong applied different perspectives. Hwajeogyeon Pond located by the Hantangang River is illustrated from a bird's-eye perspective to present a panoramic view of the surroundings and rocks. Similarly, the scenery around Uhwajeong Pavilion by the Imjingang River are depicted from the same perspective. A worm's-eye view was selected for Samseongdae Cliff in Tosangun in the upper regions of the Imjingang River and for Nakhwaam Rock. The scenes of Jeong Su-yeong's mountain outings include pavilions and small temple mainly. In the case of Jaeganjeong Pavilion on Bukhansan Mountain, its actual location remains unidentified since the pavilion did not lead to the route of the boating trip to the system of the Hangang River and was separately depicted from other trips to the mountains. I speculate that Jaeganjeong Pavilion refers to a pavilion either in one of the nine valleys in Wooyi-dong at the foot of Bukhansan Mountain or in Songajang Villa. Since these two pavilions are situated in the valleys of Bukhansan Mountain, their descriptions in written texts are similar. As for Gwanaksan Mountain, Chwihyangjeong and Ilganjeong Pavilions as well as Geomjisan Mountain in the Bukhansan Mountain range are depicted. Ilganjeong Pavilion was a well-known site on Gwanaksan that belonged to Shin Wi. In this handscroll, however, Jeong Su-yeong recorded objective geographic information on the pavilion rather than relating it to Shin Wi. "Chwihyangjeong Pavilion" is presented within the walls, while "Geomjisan Mountain" is illustrated outside the walls. Handscroll of a Sightseeing Trip to the Hangang and Imjingang Rivers also includes two small temples, Mangwolam and Okcheonam, on Dobongsan Mountain. The actual locations of these are unknown today. Nevertheless, Gungojip (Anthology of Gungo) by Yim Cheonsang relates that they were sited on Dobongsan Mountain. Compared to other painters who stressed Dobong Seowon (a private Confucian academy) and Manjangbong Peak when depicting Dobongsan Mountain, Jeong Su-yeong highlighted these two small temples. Jeong placed Yeongsanjeon Hall and Cheonbong Stele in "Mangwolam small temple" and Daeungjeon Hall in front of "Okcheonam small temple." In addition to the buildings of the small temple, Jeong drew the peaks of Dobongsan Mountain without inscribing their names, which indicates that he intended the Dobongsan peaks as a background for the scenery. The Handscroll of a Sightseeing Trip to the Hangang and Imjingang Rivers is of great significance in that it embodies Jeong Su-yeong's personal perceptions of scenic spots on the outskirts of Hanyang and records his trips to these places.