• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.1
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.20-28
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• 1999

This study was conducted to reveal the effect of some meterological factors on the weight of cone and seed per cone in Korean white pine (Pinus koraiensis SIEB. et ZUCC.). The weight of cone and seed per cone for 7 years from 1992 to 1998 on 45(1992) year-old trees and some meterological factors for 9 years from 1990 to 1998 were surveyed in Hongcheon-Gun region, Gangweon-Do. Simple correlations and multiple regression between weight of cone and seed per cone and some meterological factors were analyzed. The results obtained from the above experiments were as follows: 1. Positive correlations were found between weight of cone and monthly mean temperature of February in flower bud differentiation year. number of annual hoarfrost days of the cone production year monthly mean temperature of may in the cone production year, as July respectively. There were negative correlations between weight of cone and monthly mean temperature of august in the flowering year, wind speed of April in the flower bud differentiation year, number of clear days of december in the flowering year, number of annual cloudy days of the flowering year, number of precipitation days of june in the flowering year, number of annual precipitation days of the flowering year, number of annual cloudy days of March in the cone production year. number of annual cloudy days from march to October in the flowering year as well as number of precipitation from march to october in the flowering year. 2. Positive correlation between weight of seed per cone and number of hours with sunshine duration of June in the flowering year, the percentage of sunshine duration of June in the flowering year, number of clear days of June in the flowering year. monthly mean temperature of may in the cone production year. as well as monthly mean temperature of July in the cone production year were found. Negative correlations were recognized between weight of seed per cone and monthly mean temperature of January in the flowering year, monthly mean temperature of august in the flowering year, wind speed of april in the flower bud differentiation year, number of annual cloudy days of the flowering year, number of precipitation days of June in the flowering year, number of annual cloudy days from March to October in the flowering year as well as number of precipitation from march to October in the flowering year.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.52-56
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• 1985

For the fundamental studies of radiation breeding in edible marine algae, the biological effects on conchospores of Porphyra species by gamma-irradiation were examined. Two varieties, Keun-cham-gim (Porphyra tenera Kjell. form tamatsuensis Miura) and Saga No.5, were chosen for this study, and their conchospores after r-irradiation($5.0{\sim}20.0$ KR) were cultured for 50 days. The results obtained were summarized as follows. 1. Gamma-irradiation in less than the dose of 20KR did not affect germination of conchospores, and almost all spores grew into two cells germ in 24 hours after irradiation, but withering germs were gradually increased in number according to higher exposure within 5 days old culture. 2. High irradiation caused the induction of giant cells, abnormal useless growth of hold-fast, lumpish thalli and callus-like lumpy tissues. 3. The liberation of neutral spores from young germs and carpospores from mature thalli were observed on the frond exposed at $10{\sim}20$ KR irradiation. All spores were normal in division and its size. 4. The best irradiation effect on growth of Keun-cham-gim was observed at 10 KR dose, whose growth-rates were $140\%$ in wet weight and $108\%$ in mean frond area, but only $48\%$ was recorded in wet weight at 20 KR exposure. Saga No.5 were in contrast with Keun-cham-gim, and their most growth-rate was $400\%$ in wet weight ($258\%$ in frond area) at 10 KR irradiation and the worst was $20\%$ at the dose of 20 KR. 5. The withering phenomenon to death by treatment of gamma-ray presented substantial difference between two varieties. Survival rate compared with control in Keun-cham-gim was $70.7\%$ at 20 KR, but that in Saga No.5 recorded $47.0\%$ at same dose. 6. Synthesizing the results of high and low r-irradiation, it was suggested tat high r-irradiation in more than 5.0 KR inhibited conspicuously the growth of germs derived from conchospores, and about half of them withered at 15.0 KR dose or more.

• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.378-389
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• 2006

The purpose of this study was to compare the sealing ability of root canal obturation with or without the treatment of smear layer. Eighty extracted human teeth with one canal were selected Instrumentation was performed with crown-down technique. After instrumentation, root canals of the NaOCl group and NaOCl-6 group were irrigated with 3% NaOCl. EDTA group and EDTA-6 group were irrigated with 17% EDTA. Then all teeth were obturated using continuous wane obturation technique NaOCl group and EDTA group were immersed in methylene blue solution for 84hours. NaOCl-6 group and EDTA-6 group were immersed in methylene blue solution for 6months. The teeth were sectioned at 1.5 mn (Level 1), 3.0 mm (Level 2) and 4.5 mm (Level 3) from the root apex. The length of dye-penetrated inter-face and the circumferential length of canal at each level were measured using Sigma-Scan Pro 5.0. 1. The mean leakage ratio was decreased cervically. 2. NaOCl group showed higher mean leakage ratio than EDTA group at each level. But there was significant difference at level 1 only (p < 0.05). 3. NaOCl-6 group showed higher mean leakage ratio than EDTA-6 group at each level. But there was significant difference at level 1 only (p < 0.05). 4. NaOCl-6 group showed higher mean leakage ratio than NaOCl group at each level. But there was significant difference at level 1 only (p < 0.05). 5. EDTA-6 group showed higher mean leakage ratio than EDTA group at each level. But there was no significant difference. 6. In NaOCl group and NaOCl-6 group, scanning electron micrographs of tooth sections generally covered with smear layer. In EDTA group and EDTA-6 group, tooth sections showing the penetration of sealers to opened dentinal tubules. The results suggest that removal of smear layer was effective to reduce the apical microleakage of the root canal.

• Journal of Korean Society of Forest Science
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• v.44 no.1
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• pp.26-35
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• 1979

Factors affecting the survival of out planted Cryptomena and Japaneses Cypress seedlings. (I) - Especially on the drying and water soaking duration ­ There are often the cases of poor survival percentage for the economic forest establishments of Cryplomeria japonica D. Don. and Chamaecyparis obtusa End. This study was carried out to investigate the survival factors of both 1-1 seedlings and Cryptomena cutting Seedlings by room drying conditions, day drying conditions, OED green water soaking treatment and drying duration at the forest nursery of Chonnam National University from February to September. 1979. The results are as follows: 1. From 11 a.m. to 3 p.m. fluctuation in then moisture contents(MC) rapidly decreased and M.C. fluctuation in indoor until 5 p.m. showed the same results with the amount of an hour fluctuation in outdoor. 2. M.C. fluctuations between OED green and non-treatment of these seedlings were silghtly different. 3. The survival percentage of OED green and non-treatment of seedlings were highly significant in the room drying conditions and the day drying conditions respectively The effects of water soaking treatment on rooting was negligible. The survival percentage of seedlings of OED green was higher than that of non-treatment. 4. Although survival percentage of Japanese Cypress was almost in accord with Cryptomena, the power of resistance to drying was lower m Japanese Cypress than m Cryptomeria. 5. Compared with Cryptomena seedlings the survival percentage of Cryptomeria cutting seedlings was higher and not influenced at all in case of being drying for two hours; but it was highly significant in interactions between the drying time and the water soaking time. 6. When Cryptomena and Japanese Cypress seedling become drying in indoor for four days, the survival percentage remarkably reduced after two days and also was highly significant among numbers of drying days.

• Journal of Ginseng Research
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• v.1 no.1
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• pp.59-78
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• 1976

In order to investigate the influences of Panax ginseng (white ginseng and red ginseng) on the anesthetic effect and toxic effect of alcohol, experimental studies .had been carried out with albino rabbits, mongolian dogs and mice. The anesthetic effect of alcohol was observed by measuring the induction time, .anesthetic time, recovery time and duration from the beginning of induction to , the recovery of anesthesia (total time), respectively. and toxic effect ($LD_{50}$) of alcohol was measured. In addition to these experiments, al cohol concentration in .blood, blood sugar level, serum transaminase (GOT and GPT) activities and serum alkaline phosphatase activity were measured. Also in order to study the clinical effect of alcohol in healthy students, code .substitution, response time and muscle coordination were tested. The results were obtained as follows. 1. In the rabbits and mongolian Jags, the induction time of anesthesia by the administration of alcohol was delayed by the pretreatment of ginseng but recovery time and total time of anestksia were markedly shortend. 2. The bleed alcohol concentration was decreased by the pretreatment of ginseng , but not affected in mongolian dogs. 3. The blood sugar level, serum transaminase (GOT and GPT) activities and alkaline phoshatase activity in rabbits and dogs induced by the administration of alcohol were affected by the Pretreatment of ginseng. Because those were included within normal ranges, the differnces have no remarkable significance. 4. Liver alcohol dehydrogenase activity of rabbit was increased by the treatment of ginseng, especially it was markedly increased by the treatment of red ginseng 5. The average lethal dose of alcohol to mice was increased by the pretreatment. of ginseng, especially it was markedly increased by the pretreatment of red .ginseng. 6. In the clinical experiments, the blood alcohol concentration induced by alcohol administration was not affected by the pretreatment of ginseng whereas the bleed sugar level was increased. Blood alcohol concentration and bleed sugar level were measured after three hours alcohol administration. 7. The response time of healthy students administered with alcohol was markedly shortened by the pretreatment of ginseng but the experiments on the code substitution and muscle coordination were not affected.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.2
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• pp.39-44
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• 2020

Recently, numerous researches are being conducted in flexible substrate to apply to wearable devices. Particularly, Conductive substrate researches that can implement the wearable devices on clothing are massive. In this study, we formed fiber substrate spraying CNT and Pd mixed solution on it and plated metal layer with electroless plating. Used SEM equipment and EDS analysis to analysis structure of the plated fiber substrate and discovered Ni layer was created. For check electrical properties, mapping was performed to check surface resistance and distribution of resistance of electroless plated fiber substrate with 4-point probe. It was confirmed that conductivity was improved as the duration of electroless plating was increased, and it was found that distribution of resistance by surface location was uniform. Changes in resistance due to mechanical stress were measured through tensile, bending, and twisting tests. As a result, it was confirmed that resistance change of flexible substrate gradually disappeared as plating time increased. Using UTM (Universal testing machine), it was analyzed mechanical properties of the electroless plated substrate with respect to changes in plating time were improved. In the case of conductive fiber substrate in which electroless plating was performed for 2 hours, tensile strength was increased by 16 MPa than fiber substrate. Based on these results, we found that Ni-CNT-Fabric flexible substrate is adequate for clothing-intergrated conductive substrate and we positively expect that this experiment shows flexible substrate can adapt to and develop not only a wearable device technology but also other fields needing flexibility such as battery, catalyst and solar cell.

• Journal of agricultural medicine and community health
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• v.17 no.1
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• pp.34-45
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• 1992

In this county, the gap between the urban 'haves' and the rural 'have-nots' continues to be an increasing problem. WHO and UNICEF see primary health care(PHC) as the key to achieving an acceptable level of health throughout the world as a community development. PHC is essential health care made accessible to individuals and families in the community by means acceptable to them. It is the first level of contact of individual, the family, and community with the national health system. It includes at least education on health system. It includes at least education on health problems, promotion of food supply, MCH including family planning, immunization against infectious diseases, control of endemic diseases, treatment of common diseases and injuries, promotion of mental health, and provision of essential drugs. However, of the aboves, education concerning of mental health problems and the methods to identify, prevent, and control them is the principal step of establishment. In Korea, the category of PHC worker includes the physician as public doctor and nurse as primary health care practitioner and community health leader as village health worker. PHC workers of the aboves will thus function best if they are appropriately trained to respond to the health needs of the community. However in this country, since the national PHC service project launched in 1980, the government has not developed and performed appropriate and enough education and training activities. In light of above reasons, several categories of health education activities had been planned and performed being aimed at above specific target groups and the main focus was on the village health workers for about one year from July 1991 to July 1992 in Yeoju Kun of Kyonki Province. At the end of the period, evaluation of education input was carried out to measure the improvement of healthful life of people in terms of awareness, attitude, and practice. At the end of the period, evaluation of education input was carried out to measure the improvement of healthful life of people in terms of awareness, attitude, and practice. The totals of 80 village health workers, 13 public health practitioners and 9 public docters took in the course of health education for a few hours at every month and the evaluation works of educational effect were taken. The results the study were as follows. 1) Number of persons who realized the maxim "health care of the people is a duty of the government" increased after the education course, On the other hand, the rate of satisfaction on the effort of government for health promotion of the people decreased. 2) Public doctors and primary health care practitioners(nurses) liked and enjoyed the education schedule as a meeting of peer group. It provided chances of communication with staffs of Korea University Hospital. It was said that lectures covered great deal of knowledge and technic they urgently needed in the field. 3) After finishing the education course, more of village health workers(VHW) thought they adapted themselves to their roles and functions showing increased number of home visit and contact with primary health care practitioners by month. 4) In case of patient refer, VHW preferred primary health care practitioners to public doctors. 5) Capability of VHWs in most of their functions increased dramatically after when the education course finished except tuberculosis control.

• Journal of Acupuncture Research
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• v.22 no.3
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• pp.105-112
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• 2005

Obiective : The purpose of this study was to assess the effect of acupuncture treatment for chronic headache patients using power spectrum analysis of the heart rate variability(HRV). Methods : 15 clinical experiment participants were gathered and through a questionnaire patients who experienced headache for more than 4 hours a day and more than IS days per month were qualified as Chronic Headache patients. Treatment was afplied 2 times a weeks for 8 weeks. The acupoints, GV2O, HN23, ST8, HN46, TEl7, GB2O, LI2O, LI11, LI14, ST36, and LR3 were stimulated for 20 minutes. The effects of acupuncture treatment were analyzed using power spectrum analysis of the HRV. HRV was recorded before and after acupuncture treatment. Results : HRV before and after treatment was compared after 8 weeks of acupuncture treatment. Increase in mean values of SDNN and RMSSD were observed but the increases were not statistically significant. Increase in mean values of TP, LF and HF were observed but, the increase was significant(p<0.05) only in TP. Conclusions : The results suggest that acupuncture treatment on chronic headache patients can increase the activity of autonomic nervous system. Further use of HRV for quantitative analysis of acupuncture treatment on autonomic nervous system related symptoms is suggested.

• Journal of Acupuncture Research
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• v.22 no.1
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• pp.117-130
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• 2005

Objective : Generation after generation, by Oriental medicine literatures, Soyo-san has been used as a clinical prescription that is important to climacteric syndrome, and also has been used extensively to psyco-neurotic problems, melancholia and stress symptoms. The experimental study of Soyo-san's effect has been reported, but the effect of herbal acupuncture solution by Soyo-san is not reported yet. Thus the purpose of this experiment is to test whether Herbal acupuncture of Soyo-san have anti-stress or antidepressant effects in the menopause or not. Methods : Female Sprague-Dawley(240-260g) rats were used. Temperature controlled within $20-25^{\circ}C$. Water and food not limited, and Manipulated the day and night 12 hours each. In the experiment, enforced Morris water maze after immobilization stress for 5 minutes, and operating Herbal acupuncture of Soyo-san 30 minutes before stress every day during 7 days. Flowed through by 4% paraformaldehyde and fixed brain tissue after test of 7 days. Results : 1) As a result of the acquisition test, Soyo-san group was recognized by significant difference compared to Ovx group and the retention test Soyo-san group increased significantly compared to Sham and Ovx group. 2) Soyo-san group showed that the degree of revealation of Tyrosine hydroxylase decreased comparing to Ovx group in ventral tegmental area and that of Choline acetyltransferase increased comparing to Ovx group in CAI region of Hippocampus. Conclusion : As a result of this experiment to grasp those effects on postmenopausal depression or learing disability and memory disorder, the possibility of Herbal acupunture by Soyo-san is warranted as a suitable treatment to relieve women's monopausal depression and those of stress reaction, improving tearing disability and memory disorder.