• Title/Summary/Keyword: Exposure Rates

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Effects of the Hormone Mimetid Insecticide Tebufenozide on Chironomus flaviplumus Larvae (Chironomus flaviplumus (Diptera: Chironomidae)에 잠재적 환경교란물질, Tebufenozide 처리효과)

  • 곽인실;이원철
    • Korean Journal of Environmental Biology
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    • v.21 no.1
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    • pp.72-76
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    • 2003
  • We investigated the effects of molting-hormone insecticide tebufenozide on fourth larvae of the midge C. flaviplumuon in growth development from fourth-instar to adult. Fourth-instar larvae were exposed test concentrations were chosen control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$, 60 $\mu\textrm{g}$$L^{-1}$ and 100$\mu\textrm{g}$$L^{-1}$. In control and 10 $\mu\textrm{g}$$L^{-1}$, 10~20% individuals succeed adults while low emergence rates were observed surplus 30 $\mu\textrm{g}$$L^{-1}$. Death larvae appeared a various day along the concentration. We observed the converged day: control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$ and 60~100 $\mu\textrm{g}$$L^{-1}$ were day 4 to day 18, day 13 to day 16, day 9 to day 17 and day 9 to day 15, respectively. Therefore we concerned a tendency that exposure concentration was high, death period was short. Also, due to molting hormone disruption, development of midge was postponed relatively low concentration such as 10 $\mu\textrm{g}$$L^{-1}$. The converged days of pupa stage revealed control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$ and 60~100$\mu\textrm{g}$$L^{-1}$ were day 11~15, day 16~20, day 9~15 and day 5~9, respectively. About 10% individuals grow up the pupa-stage in 60~100 $\mu\textrm{g}$$L^{-1}$ condition. Sex ratio of the emerged adults was not different in this study. Death pupae frequently appeared in day 13~16 in control, day 6~23 in 10 $\mu\textrm{g}$$L^{-1}$, day 13~16 in 30 $\mu\textrm{g}$$L^{-1}$ and day 6~16 in 60~100 $\mu\textrm{g}$$L^{-1}$.

Measuring the Third-Person Effects of Public Opinion Polls: Focusing On Online Polls (여론조사보도에 대한 제3자효과 검증: 온라인 여론조사를 주목하며)

  • Kim, Sung-Tae;Willnat, Las;Weaver, David
    • Korean journal of communication and information
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    • v.32
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    • pp.49-73
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    • 2006
  • During the past decades, public opinion polls have become an ubiquitous tool for probing the complexity of people's beliefs and attitudes on a wide variety of issues. Especially since the late 1970s, the use of polls by news organizations has increased dramatically. Along with the proliferation of traditional polls, in the past few years pollsters and news organizations have come to recognize the advantages of online polls. Increasingly there has been more effort to take the pulse of the public through the Internet. With the Internet's rapid growth during the past years, advocates of online polling often emphasize the relative advantages over traditional polls. Researchers from Harris Black International Ltd., for example, argue that "Internet polling is less expensive and faster and offers higher response rates than telephone surveys." Moreover, since many of the newer online polls draw respondents from large databases of registered Internet users, results of online polls have become more balanced. A series of Harris Black online polls conducted during the 1998 gubernatorial and senatorial elections, for example, has accurately projected the winners in 21 of the 22 races it tracked. Many researchers, however, severely criticize online polls for not being representative of the larger population. Despite the often enormous number of participants, Internet users who participate in online polls tend to be younger, better educated and more affluent than the general population. As Traugott pointed out, the people polled in Internet surveys are a "self selected" group, and thus "have volunteered to be part of the test sample, which could mean they are more comfortable with technology, more informed about news and events ... than Americans who aren't online." The fact that users of online polls are self selected and demographically very different from Americans who have no access to the Internet is likely to influence the estimates of what the majority of people think about social or political issues. One of the goals of this study is therefore to analyze whether people perceive traditional and online public opinion polls differently. While most people might not differentiate sufficiently between traditional random sample polls and non representative online polls, some audiences might perceive online polls as more useful and representative. Since most online polls allow some form of direct participation, mostly in the form of an instant vote by mouse click, and often present their findings based on huge numbers of respondents, consumers of these polls might perceive them as more accurate, representative or reliable than traditional random sample polls. If that is true, perceptions of public opinion in society could be significantly distorted for those who rely on or participate in online polls. In addition to investigating how people perceive random sample and online polls, this study focuses on the perceived impact of public opinion polls. Similar to these past studies, which focused on how public opinion polls can influence the perception of mass opinion, this study will analyze how people perceive the effects of polls on themselves and other people. This interest springs from prior studies of the "third person effect," which have found that people often tend to perceive that persuasive communications exert a stronger influence on others than on themselves. While most studies concerned with the political effects of public opinion polls show that exit polls and early reporting of election returns have only weak or no effects on the outcome of election campaigns, some empirical findings suggest that exposure to polls can move people's opinions both toward and away from perceived majority opinion. Thus, if people indeed believe that polls influence others more than themselves, perceptions of majority opinion could be significantly altered because people might anticipate that others will react more strongly to poll results.

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Aquaporin in bleomycin induced lung injury (급성 폐손상 동물모델에서 aquaporin 수분통로의 발현)

  • Jang, An-Soo;Park, Jong-Sook;Lee, June-Hyuk;Park, Sung-Woo;Kim, Do-Jin;Uh, Soo-Taek;Kim, Yong-Hoon;Park, Choon-Sik
    • Tuberculosis and Respiratory Diseases
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    • v.60 no.3
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    • pp.330-336
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    • 2006
  • Background : Aquaporins (AQPs) may play a role in the pathogenesis of pulmonary inflammation and edema. This study investigated the role ofAQPs in acute lung injury following bleomycin inhalation in rats. Methods : Sprague-Dawley rats were treated via inhalation with 10 U/kg bleomycin hydrochloride dissolved in 5 ml of normal saline. The control rats were treated with 5 ml normal saline. The animals (n = 6-8 rats per group) were sacrificed at 4, 7, and 14 d. The changes in AQP1, AQP4, and AQP5 expression levels over time were analyzed by Western blotting. The nitrate and nitrite concentrations in the bronchoalveolar lavage fluid (BALF) were measured using a modified Griess reaction. ELISA was used to check cytokines. Results : The respiration rates were significantly higher 4 and 7 days after the bleomycin treatment compared with those of the control rats. The tidal volume was lower in rats at 4 days after the bleomycin treatment, and the wet/dry weights of the lung were significantly higher than those of the control group. The nitrite and nitrate concentrations in the BALF from the rats at 4 days after exposure to bleomycin were greater than those from the saline-treated rats. Immunoblotting studies demonstrated that the AQP1 and AQP4 expression levels were lower in the rats at 4 days. However, the AQP4 expression level was higher at 7 days. The AQP5 expression level increased at 4, 7 and 14 days after the bleomycin treatment. Conclusion : This study demonstrates that AQPs are expressed differently in bleomycin-induced pulmonary edema.

Vegetation Structure and Site Characteristics of Syringa fauriei Population in South Korea (버들개회나무(Syringa fauriei H. Lév.) 개체군의 식생구조와 입지특성)

  • Hwang, Yong;Kim, Yong-Yul;Kim, Mu-Yeol
    • Korean Journal of Environment and Ecology
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    • v.30 no.4
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    • pp.762-770
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    • 2016
  • This study intended to investigate environmental factors including soil and vegetation in order to understand the environmental and ecological characteristics of the Korean endemic species, Syringa fauriei. Syringa fauriei is mainly distributed along the valley and riverside of the Gangwondo and its population is located at an elevation of 121~520m. Consequent to a vegetation survey within natural populations, a total of 320 taxa were identified from 20 quadrates in 4 natural populations. The Syringa fauriei population was classified into Securinega suffruticosa dominant population, Acer pseudosieboldianum dominant population, Amorpha fruticosa dominant population and Sorbaria sorbifolia var. stellipila dominant population. According to the physical and chemical soil analysis, Syringa fauriei habitats contained 1.98~2.81% of organic matter and 0.13~0.20 mg/kg of total nitrogen. The concentrations of cation exchange capacities $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were $0.10{\sim}0.33cmol^+/kg$, $3.44{\sim}20.53cmol^+/kg$, and $0.34{\sim}0.95cmol^+/kg$, respectively. Positive ion substitution capacity was $8.08{\sim}13.68cmol^+/kg$. The pH was 6.28~7.74. The importance value of Deutzia glabrata, Fraxinus rhynchophylla, Alangium platanifolium var. trilobum, Syringa fauriei, Juglans mandshurica, and Salix koreensis in the Syringa fauriei population were 86.99%, 43.97%, 23.01%,18.52, 18.40%, and 11.56%, respectively. Correlation analysis between the vegetation of Syringa fauriei populations and its environmental factors using DCCA revealed that the altitude above sea level and $Mg^{2+}$ were the most influential factors, while dominant populations of Securinega suffruticosa and Acer pseudosieboldianum were spread across areas with high percentages of pH, CEC, and $Mg^{2+}$. Acer pseudosieboldianum population was dispersed in areas with higher $K^+$ compared to Securinega suffruticosa population. The dominant population of Amorpha fruticosa was found to live in places with high altitudes above sea level and with high rates of available phosphate, $K^+$, and rock-exposure.

Growth and Physiological Characteristics of Five Common Foliage Plant Species Grown under the Influence of Static Magnetic Field (정자기장 처리에 따른 실내 관엽식물의 생육 및 생리적 특성 변화)

  • Lee, Seong Han;Woo, Su Young;Kwak, Myung Ja
    • Horticultural Science & Technology
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    • v.30 no.5
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    • pp.484-492
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    • 2012
  • The present study aimed to investigate the effect of static magnetic field (SMF) on the growth and physiological characteristics of common indoor plant species. Five foliage plant species, Spathiphyllum spp., Ardisia pusilla DC., Syngonium podophyllum, Peperomia pereskiifolia, and Pilea cadierei were potted into plastic pot equipped with round type anisotropic sintered NdFeB permanent magnet inside the pot. The surface magnetic flux density of each magnet was 3,500 G. After 6 months of growth period, the biomass accumulations of Spathiphyllum, A. pusilla, and P. cadierei under SMF were statistically higher than those of controls. Tissue water content also increased under the influence of SMF in most species. The photosynthetic rate of Spathiphyllum under SMF significantly increased but other species showed no significant difference compared with control. Although there was no significant increase in the photosynthetic rates of A. pusilla, and P. cadierei, they showed remarkable increase in total fresh weight under SMF. This suggests that the demand of assimilates for normal metabolism could be decreased under magnetic influence and thereby biomass accumulation could be more favored. But this is not always true for all plant species because P. pereskiifolia in this experiment, showed no changes in both photosynthetic rate and biomass accumulation. Leaf nitrogen and chlorophyll contents were enhanced significantly in most plant species under influence of SMF. Chlorophyll a/b ratio also increased by SMF. Although there might be a limitation depending on plant species, these results suggest that long-term exposure to SMF might allow plant to have an enhanced acclimation capacity against environmental fluctuations and optimal application of SMF could increase the practical use of indoor plants such as an attempt to improve indoor air quality.

Characteristics of Percutaneous Absorption of Glycol ethers (Glycol ethers에 대한 피부 투과 특성)

  • Lee, Han-Seob;Choi, Sung-Boo;Kim, Nac-Joo;Keun, Jang-Hyoun;Hwang, Hyun-Suk;Baek, Jung-Hun;Choi, Jin-Ho;Lee, Ho-Joon
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.1
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    • pp.116-126
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    • 2013
  • Glycol ethers are a group of solvents based on alkyl ethers of ethylene glycol commonly used in paints. These solvents typically have a higher boiling point, together with the favorable solvent properties of lower-molecular weight ethers and alcohols. The word "Glycol ethers" was registered as a United States trademark by Union Carbide Corp. Typically, glycol ethers are found in pharmaceuticals, sunscreens, cosmetics, inks, dyes and water based paints. On the other hand, glycol ethers are used in degreasers, cleaners, aerosol paints and adhesives. Most glycol ethers are relatively water soluble, biodegradable and only a few are considered toxic. Therefore, they are unlikely to pose an adverse risk to the environment. Recent study suggests that occupational exposure to glycol ethers is related to low motile sperm count in men, but the finding has been disputed by others. In this study, skin permeation of 3 types glycol ethers were studied in vitro using matrix such as solvent and detergent. The absorption of glycol ethers[methyl glycol ethers(MC), ethyl glycol ethers(EC) and butyl glycol ethers(BC)] has been measured in vitro through rat skin. Epidermal membranes were set up in Franz diffusion cells and their permeability to PBS measured to establish the integrity of the skin before the glycol ethers were applied to the epidermal surface. Absorption rates for each glycol ethers were determined and permeability assessment made to quantify any irreversible alterations in barrier function due to contact with the esters. Types of glycol ethers in vitro experimental results on MC> EC> BC quickly appeared in the following order: skin permeation was beneficial to the skin permeation small molecular weight, the difference in chemical structure, such as hydrophilic, because with the partition coefficient and solubility mechanisms and passive diffusion to increase the speed at which transmission is considered.

Effect of the Space Dose Rate due to Change of X-ray Irradiation Energy and MU Value in Radiation Therapy Room (선형가속기의 엑스선 조사에너지와 MU값의 변화가 치료실 내 공간선량률 변화에 미치는 영향)

  • Kwon, Hyeonghyo;Park, Geonryul;Kim, Minji;Jo, Yeongdan;Kim, Youngjae
    • Journal of the Korean Society of Radiology
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    • v.14 no.2
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    • pp.77-83
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    • 2020
  • This study investigated the radiation protection of therapeutic radiologists. Based on the change in X-ray energy and MU value, the space dose rate in the treatment room after the irradiation was measured. 6MV, 10MV and 15MV photon beams were exposed to radiation inside the treatment room based on 300MU, 600MU and 1000MU using a linear accelerator. And repeated 10 times under the same conditions. As a result of the experiment, 0.1555 μSv/h for 6MV 300MU, 0.157 μSv /h for 300sec, 0.152 μSv/h, 0.156 μSv/h for 600MU, and 0.157 μSv/h 0.152 μSv/h for 1000MU. 300MU of 10MV was 0.49 μSv/h, 0.309 μSv/h, and 0.69 μSv/h, 0.416 μSv/h for 600MU, respectively, and 1000MU was 0.977 μSv/h and 0.478 μSv/h, respectively. The 300MU of 15MV was 3.02 μSv/h, 1.2 μSv/h, 5.459 μSv/h at 600MU, 7.34 μSv/h at 1.836 μSv/h 1000MU, and 2.709 μSv/h. The average spatial dose rate of 6MV was not significantly different from the natural spatial dose rate in the treatment room. High spatial dose rates were measured at 10 MV and 15 MV and were attenuated over time. Therefore, entering the treatment room after a certain period of time (more than 60 seconds) is considered to be effective to prevent the exposure dose of radiation workers.

MODULATION OF INTRACELLULAR pH BY $Na^+/H^+$ EXCHANGER AND $HCO_3^-$ TRANSPORTER IN SALIVARY ACINAR CELLS ($Na^+/H^+$ exchanger와 $HCO_3^-$ transporter에 의한 흰쥐 타액선 선세포내 pH 조절)

  • Park, Dong-Bum;Seo, Jeong-Taeg;Sohn, Heung-Kyu;Lee, Jong-Gap
    • Journal of the korean academy of Pediatric Dentistry
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    • v.25 no.2
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    • pp.352-367
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    • 1998
  • Intracellular pH (pHi) plays an important role in the regulation of cellular processes by influencing the acitivity of various enzymes in cells. Therefore, almost every type of mammalian cell possesses an ability to regulate its pHi. One of the most prominent mechanisms in the regulation of pHi is $Na^+/H^+$ exchanger. This exchanger has been known to be activated when cells are stimulated by the binding of agonist to the muscarinic receptors. Therefore, the aims of this study were to compare the rates of $H^+$ extrusion through $Na^+/H^+$ exchanger before and during muscarinic stimulation and to investigate the possible existence of $HCO_3^-$ transporter which is responsible for the continuous supply of $HCO_3^-$ ion to saliva. Acinar cells were isolated from the rat mandibular salivary glands and loaded with pH-sensitive fluoroprobe, 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein(BCECF), for 30min at room temperature. Cells were attached onto the coverglass in the perfusion chamber and the changes in pHi were measured on the iverted microscope using spectrofluorometer. 1. By switching the perfusate from $HCO_3^-$-free to $HCO_3^-$-buffered solution, pHi decreased by $0.39{\pm}0.02$ pH units followed by a slow increase at an initial rate of $0.04{\pm}0.007$ pH units/min. The rate of pHi increase was reduced to $0.01{\pm}0.002$ pH units/min by the simultaneous addition of 1 mM amiloride and $100{\mu}M$ DIDS. 2. An addition and removal of $NH_4^+$ caused a decrease in pHi which was followed by an increase in pHi. The increase of pHi was almost completely blocked by 1mM amiloride in $HCO_3^-$-free perfusate which implied that the pHi increase was entired dependent on the activation of $Na^+/H^+$ exchanger in $HCO_3^-$-free condition. 3. An addition of $10{\mu}M$ carbachol increased the initial rate of pHi recovery from $0.16{\pm}0.01$ pH units/min to $0.28{\pm}0.03pH$ units/min. 4. The initial rate of pHi decrease induced by 1mM amiloride was also increased by the exposure of the acinar cells to $10{\mu}M$ carbachol ($0.06{\pm}0.008pH$ unit/min) compared with that obtained before carbachol stimulation ($0.03{\pm}0.004pH$ unit/min). 5. The intracellular buffering capacity ${\beta}1$ was $14.31{\pm}1.82$ at pHi 7.2-7.4 and ${\beta}1$ increased as pHi decreased. 6. The rate of $H^+$ extrusion through $Na^+/H^+$ exchanger was greatly enhanced by the stimulation of the cells with $10{\mu}M$ carbachol and there was an alkaline shift in the activity of the exchanger. 7. An intrusion mechanism of $HCO_3^-$ was identified in rat mandibular salivary acinar cells. Taken all together, I observed 3-fold increase in $Na^+/H^+$ exchanger by the stimulation of the acinar cells with $10{\mu}M$ carbachol at pH 7.25. In addition, I have found an additional mechanism for the regulation of pHi which transported $HCO_3^-$ into the cells.

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Effects of Kinds of Cryoprotectants on the Characteristics of Frozen Fowl Semen (닭 정액 동결 시 동결 보호제가 정액 성상에 미치는 영향)

  • Choi, Jin Seok;Shin, Dan-Bi;Ko, Yeoung-Gyu;Do, Yoon-Jung;Byun, Mijeong;Park, Soo-Bong;Seong, Hwan-Hoo;Kim, Hyun;Kong, Il-Keun;Kim, Sung Woo
    • Korean Journal of Poultry Science
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    • v.40 no.3
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    • pp.171-178
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    • 2013
  • The purpose of this study was to evaluate the sperm viability, normal acrosome and mitochondrial activity in the frozen-thawed fowl semen by different cryoprotectants. The experiment was carried out on 10 sexually adult roosters of Ogye. The semen was collected twice a week and pooled semen was diluted 1:1 EK extender containing no cryoprotectant at $5^{\circ}C$. After equilibration for 30 minutes, diluted chicken semen was diluted 1:1 extender containing either 7% dimethylacetamide (DMA), 7% dimethylformamide (DMF) or 7.5% methylacetamide (MA) at final concentration and was put in 0.5 mL plastic straws and frozen for 30 minutes by exposure to liquid nitrogen vapor 4 cm above the surface of liquid nitrogen, followed by plunging into liquid nitrogen. Frozen semen was thawed in water bath at $5^{\circ}C$ for 2 minutes. For cytometric analysis, the frozen-thawed semen was diluted with EK extender to a final concentration of 90 million spermatozoa per mL. Sperm membrane integrity was evaluated as SYBR-14 and propidium iodide (PI). Acrosome integrity was assessed with fluorescein isothiocyanate-labeled PSA and PI. The percentage of mitochondrial function was estimated by using Rhodamine123 (R123) and PI. In conclusion, freezing rooster semen by using 7% DMF as cryoprotectant was significantly highest in rates of survival and mitochondrial function while its rate of damage of acrosome was significantly lowest. As a result, DMF is the cryoprotectant that has the lowest influences on sperm membranes and acrosome integrity. Therefore it could be used for freezing method of animal genetic conservation method for poultry diversity.

Effect of Ethylene Glycol(EG) and Propylene Glycol(PG) on the Viability of Frozen-thawed Primordial Germ Cells(PGCs) on Korean Native Chicken(Ogye) by Vitrification (한국재래닭(오계)의 유리화 동결 시 생존율에 미치는 Ethylene Glycol(EG)과 Propylene Glycol(PG)의 영향)

  • Kim, Hyun;Kim, Dong Hun;Han, Jae Yong;Choi, Sung Bok;Ko, Yeoung Gyu;Do, Yoon Jung;Seong, Hwan-Hoo;Kim, Sung Woo
    • Korean Journal of Poultry Science
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    • v.40 no.3
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    • pp.197-205
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    • 2013
  • This study established a method for preserving chicken primordial germ cells (PGCs) that enables long-term storage in liquid nitrogen ($LN_2$) for preservation of the species. The purpose of this study was to compare the effects of Ethylene Glycol (EG) and Propylene Glycol (PG) on viability of cryopreserved PGCs with vitrification in Korean Native Chicken (Ogye), and to fine should be find or to the optimal protocol for PGCs freezing. One of the important components of cryopreservation process is cryopreservation medium that plays a vital role in preventing cellular injury during freeze-thawing. Cryoprotective agents have been known to improve cell viability after freeze-thawing. PGCs obtained from the germinal gonade of 5.5~6 day (stage 28) chick embryos, using the MACS method were suspended in a freezing medium containing a freezing and protecting agents. Gonads were harvested from stage 28 chick embryos and pooled in groups of 10E embryos, contributing gonads to the cell suspension. The gonadal cells, including PGCs, were then frozen in 1 of the following cryoprotectant treatments: 2.5% EG, 5% EG, 10% EG, 2.5% PG, 5% PG, 10% PG, and 0% cryoprotectant as a control. Effects of exposure to vitrification solution and vitrification, with different concentrations of the cryoprotectant solution, were examined. After freezing and thawing, survival rates of the frozen-thawed PGCs from the 0, 2.5, 5, 10 and 15% EG plus FBS treatment were 44.24%, 64.51%, 85.63%, 80.51% and 73.52% (p<0.05), respectively. The viability of PGCs after freeze-thawing was significantly higher for 10% EG plus FBS treatment than for 10% PG + FBS treatment (p<0.05)(85.63% vs 66.81%). Therefore, these systems may contribute in the improvement of cryopreservation for a scarce species in birds preservation. This study established a method for preserving chicken PGC that enables systematic storage and labeling of cryopreserved PGCs in liquid N at a germplasm repository and ease of entry into a database. In the future, the importance for this new technology is that poultry lines can be conserved while work is being conducted on improving the production of germline chimeras.