• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.150-151
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• 2011

양자점 Laser Diode(LD)는 낮은 문턱전류, 높은 미분 이득을 갖으며 또한 온도변화에도 안정적이기 때문에 광통신분야에서 광원으로 양자점 LD를 사용하기 위한 연구가 계속되고 있다. 양자점은 fill factor가 낮기 때문에 양자점의 밀도를 높이거나 양자점을 적층 성장하여 fill factor를 높인다. 그러나 양자점을 적층 성장하면 각 층간의 응력, 수직적 결합, 전기적인 결합이 생기며 이는 양자점의 전기적, 광학적 특성에 영향을 미친다. 본 연구에서는 metal organic chemical vapor deposition (MOCVD)을 이용하여 InP기판 위에 자발성장 법으로 InAs 양자점을 다주기 성장하였으며 photoluminescence (PL)을 이용하여 광학적 특성을 분석하였다. precursor는 trimethylindium (TMI), trimethylgalium (TMGa), $PH_3$, $AsH_3$를 사용하였으며 carrier gas는 $H_2$를 사용하였다. InAs 양자점은 1100 nm의 파장을 갖는 InGaAsP barrier 위에 성장하였고, InAs와 InGaAsP의 성장온도는 $520^{\circ}C$이며 InAs 양자점 성장시 V/III 비는 3.66으로 일정하게 유지하였다. 그림 1은 양자점 성장시간을 0.11분으로 고정하여 3주기(A), 5주기(B), 8주기(C) 성장한 구조이며 그림 2는 양자점 성장시간을 3주기마다 0.01분씩 줄여가며 3주기는 0.11분${\times}$3(D), 6주기는 0.11분${\times}$3+0.10분${\times}$3(E), 9주기는 0.11분${\times}$3+0.10분${\times}$3+0.09분${\times}$3(F) 으로 성장한 성장구조이다. 각 성장한 시료는 PL을 이용하여 파장과 반치폭을 측정하였다. 그림 3은 양자점 성장시간을 고정한 시료 A, B, C의 PL파장과 PL반치폭 데이터이다. PL파장은 A, B, C 시료 각각 1504 nm, 1571 nm, 1702 nm이며 반치폭은 각각 140 meV, 140 meV, 150 meV이다. PL파장과 반치폭은 각각 3주기에서 6주기로 증가할 때 67 nm, 0 meV 6주기에서 9주기로 증가할 때는 131 nm, 10 meV 증가하였다. 다음 그림4는 양자점 성장시간을 조절하여 성장한 양자점 시료 D, E, F의 PL파장과 PL반치폭 데이터이다. PL파장은 D, E, F 시료 각각 1509 nm, 1556 nm, 1535 nm이며 반치폭은 각각 137 meV, 138 meV, 144 meV이다. PL파장과 반치폭은 각각 3주기에서 6주기로 증가할 때 47 nm, 1 meV 증가하였고, 6주기에서 9주기로 증가할 때는 21 nm 감소, 6 meV 증가하였다. 양자점 성장시간을 고정하여 다주기를 성장하였고 또 3주기마다 양자점 성장시간을 달리하여 다주기를 성장하였으며 PL을 이용해 광학적 특성을 연구하였다. 성장된 양자점의 PL 파장과 PL 반치폭 변화를 통해 적층구조에서 성장 주기가 늘어날수록 양자점의 크기가 증가하는 것을 확인하였고 또한 적층성장을 할 때 양자점 성장시간을 줄임으로써 양자점의 크기 변화를 제어 할 수 있었다.

• Natural Product Sciences
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• v.11 no.4
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• pp.233-239
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• 2005

The aerial parts of Gomphocarpus sinaicus Boiss. yielded four flavonoids that were identified as isorhamnetin 3-O-rhamnoglucoside (1), luteolin-7-O-glucoside-3-O-rhamnoside (2), rutin (3) and rutin-7-O-rhamnoside (4). All of the isolated flavonoids were identified by spectroscopic methods (UV, FAB-MS, $^1H-NMR\;&\;^{13}C-NMR$) and in comparison with the literature data. The isolated flavonoids 1, 2 and 4 are reported here for the first time from Gomphocarpus sinaicus Boiss. Three sets of experiments were carried out using the defatted alcoholic extract of Gomphocarpus sinaicus Boiss: the $1^{st}$ experiment indicated that the $LD_{50}$ was 49.82 mg/100 g b.wt. of intraperitoneally (i.p.) injected mice. The toxic signs were recorded within the first 24 hr post-injection. The $2^{nd}$ experiment revealed that the extract of the plant exhibited significant anti-inflammatory effects in normal rats. The $3^{rd}$ experiment was found that the tested doses of the extract in diabetic rats induced a significant decrease in serum glucose, AST, ALT, triglycerides, cholesterol and LDL, while HDL caused a significant increase.

• Toxicological Research
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• v.13 no.4
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• pp.393-400
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• 1997

The effects of superoxide dismutase(SOD) and catalase on the toxicity of paraquat(PQ) were studied using diethyldithiocarbamate(DDC), 3-amino-1,2,4-triazole(AT) which are inhibitors of Cu, Zn-SOD and catalase in rats. Sprague Dawley rats were divide into 6 groups: control, DDC, PQ, AT, DDC+PQ, and AT+PQ group. The PQ (50 mg/kg body weight(BW); about half dose of $LD_{50}$) was administered with orally, otherwise AT(1.0g/kg BW) and DDC(1.0g/kg BW) were administered by intrperitoneal(iP) injection. The survival rate of rats in PQ+AT group was significantly decreased compared with PQ group while the difference of survival rate between DDC group and DDC+PQ group was not significant. The SOD activity after administration of DDC was decreased in liver, lung and kidney, but catalase activity was not changed. The catalase activity in liver, lung and kidney of AT treated rats was decreased, while SOD activity was not changed in this group. The effects of DDC and AT to the PQ toxicity was also observed in primary cultured rat Skin fibroblasts. The viable cells that was measured with MTT method, was decreased in AT+PQ treated group compared to PQ treated group, but the difference of cell viability between DDC treat group and DDC+PQ treated group was not observed. This result, AT potentlate PQ toxicity while DDC were not affect, suggested that the decreased catalase activity lead to elevation of hydrogen peroxide levels and PQ toxicity may be correlate with the hydrogen peroxide rather than the superoxides.

• Korean journal of applied entomology
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• v.23 no.3 s.60
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• pp.166-171
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• 1984

The present studies were conducted to investigate the relative toxicity of several insecticides to the rice insect pests and the predatious spider, Pirate subpiraticus. In laboratory test by topical application, BPMC and MIPC for the plant and leafhoppers were toxic to Nilaparvata lugens, but less toxic to Pirata subpiraticus. Other carbamate insecticides such as carbaryl, carbofuran, and MTMC showed highly toxic effect on P. subpiraticus as well as N. lugens. No organophosphates showed selective toxicity to P. subpiraticus. Thiocyclam, effective to Chilo suppressalis and Sesamia inferens, had highly good selective toxicity to P. subpiraticus. In case of insecticides for Nephotettix cincticeps, BPMC only had a little selective toxicity between N. cincticeps and P. subpiraticus. Organophosphate insecticides which had been reported to induce chemical resistance to N. cincticeps showed high $LD_{50}$ value to N. cincticeps. In pot trials, dust formulation was more toxic to P. subpiraticus than emulsifiable concentrate. It was more toxic to P. subpiraticus to increase number. of insecticide application.

• Food Science of Animal Resources
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• v.25 no.4
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• pp.403-408
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• 2005

The objective of this study was to investigate the effects of supplemental levels of Bamboo vinegar (BV) on meat quality characteristics of Hanwoo. A total of 15 cows $(400.0\pm15.0\;kg)$ was fed with a commercial diet (control) or $3\%$ bamboo vinegar supplemented diets $(3\%\;BV),\;6\%$ BV for four months. Then, cows were slaughtered and M. longissimus dorsi (LD) was collected from each treatment group During storage at $4^{\circ}C$ for 21day, physico-chemical, microbiological and sensory characteristics were determined It increased (p<0.05) in at 3 and 9 days of the refrigeration storage. Hunter a value decreased (p<0.05) in the meat fed with $3\%\;and\;6\%$ BV at 1, 3 and 9 days. Hunter b value increased (p<0.05) in $3\%\;and\;6\%$ BV at 1 and 3 days. TBA and total bacterial count were significantly (p<0.05) low in $3\%\;and\;6\%$ BV at 1 and 3 days. Supplementation of $3\%\;or\;6\%$ BV showed a significant (p<0.05) decrease in cooking loss at 9 and 15 days. $3\%\;and\;6\%$ BV showed a significant (p<0.05) decrease in shear force at 1, 3 and 9 days; it tended to decrease throughout the whole storage period The treatments $3\%\;and\;6\%$ BV scored high in area of taste; taste increased significantly (p<0.05) at 1 and 3 days.

• Korean Journal of Pharmacognosy
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• v.17 no.4
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• pp.292-301
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• 1986

The combined preparations of the traditional Korean prescriptions, Sahyangsohap-won (A1) and Woohwangporyong-hwan (B1) were evaluated on pharmacological actions in rats and mice, in parallel with the preparations of their modified prescriptions (A2 and B2). The acute toxicities of the four preparations were very low of which $LD_{50}$ values were more than 4g/kg, p.o. and no systematic symptoms were found at the doses. All the preparations showed sedative action by prolongation of sleeping time induced with hexobarbital sodium. The action was more potent in the modified preparations than in the original ones. All the preparations had no anticonvulsant action both in chemoshock seizures induced by pentetrazole and strychnine and in electroshock seizure. In rat fundus preparation, A1 and A2 elicited strong contraction at the concentration of $1{\times}10^{-3}\;g/ml$ in bath, whereas B1 and B2 did neither contraction nor relaxation at the same concentration. The four preparations had no inhibitory effect against acetylcholine induced spasm. In rat intestinal preparation, the four preparations exhibited neither contraction nor relaxation. However, A1 and A2 had antagonistic effect against spasm at the concentration of $1{\times}10^{-3}\;g/ml$. Single administration of each preparation at the dose of 0.24g/kg, p.o. stimulated the secretion of pepsin in rat stomach without inciting the secretion of gastric juice. Their stimulating actions were more marked in B1 and B2 than in A1 and A2, and were more promptly exhibited in the modified preparations (A2 and B2). Accelerating action of bile secretion by single administration of each preparation was found at the dose of 0.24g/kg, p.o. in rats. All the preparations except A2 also stimulated the secretion of bile acid.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.355-360
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• 2016

The insecticidal activities of the essential oils of Artemisia vulgaris, Achillea millefolium, Anethum graveolens, Cimicifuga heracleifolia, Citrus paradisi, Chrysanthemum indicum, Eucalyptus dives, Neroli bigard, Nigella sativa, and Ruta graveolens against stored-grain insects, Plodia interpunctella and Tribolium castaneum larvae and adults were evaluated using fumigant and contact bioassays. Based on the $LD_{50}$ values in fumigant bioassay, A. millefolium ($0.12{\mu}g/cm^3$) and A. graveolens ($93.14{\mu}g\;cm^{-3}$) oil were most effective against P. interpunctella and T. castaneum adults. In addition, N. bigard ($139.11{\mu}g\;cm^{-3}$) and A. graveolens ($52.87{\mu}g\;cm^{-3}$) oil exhibit strong insecticidal activities against P. interpunctella and Tribolium castaneum larvae in contact bioassay. These results indicate that A. millefolium, A. graveolens, N. bigard, and A. graveolens oils could be effective natural acaricides for managing stored-grain insects, P. interpunctella and T. castaneum.

• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.407-415
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• 1986

This study investigated whether a correlation exists between environmental physical and biochemical factors and adherence of Candida albicans to human buccal epithelial cells by using normal and UV-irradiated strains. The results were as follows: 1. The percentage of germ tube forming activities of normal Candida albicans was 91.5% and UV-irradiated Candida albicans was 15.0%. The $LD_{50}$ of normal strains in mice were $1.0{\times}10\;cells/ml$, but could not be observed in the UV-irradiated strains even with $1.0{\times}10\;cells/ml$. It demonstrated that the virulence is decreased in the UV-irradiated strain. 2. The adherence of normal Candida albicans to human buccal epithelial cells($166{\pm}29{\sim}207{\pm}17\;cells$/100 epithelial cells) was significantly greater than UV-irradiated Candida albicans($99{\pm}21{\sim}131{\pm}25\;cells$/100 epithelial cells). 3. Candida albicans cultured at $37^{\circ}C$ adhered to buccal epithelial cells($166{\pm}16{\sim}207{\pm}17\;cells$/100 epithelial cells) in greater numbers than cultured at $25^{\circ}C$($80{\pm}15{\sim}143{\pm}22\;cells$/100 epithelial cells). 4. On comparison of the adherence of viable and nonviable(heat-killed) Candida albicans to human buccal epithelial cells, the nonviable Candida albicans demonstrated poorer adherence than viable Candida albicans. 5. Adherence in vitro of Candida albicans to human epithelial cells appeared to be effected by the pH. The adherence ability was maximum increased at pH 7.0($187{\pm}22\;cells$/100 epithelial cells) other than experimental pH. 6. The adherence was proportional to the incubation time and the Candida cell concentration in the suspension. 7. A strong correlation was shown between germ tube forming activity and increased adherence of Candida albicans to human epithelial cells, indicating that germ tube forming activity were responsible for candidal virulence.

• Journal of Chest Surgery
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• v.32 no.3
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• pp.224-236
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• 1999

Background: To evaluate the short-term effect of dynamic cardiomyoplasty on circulatory function and detect the related factors that can affect it, experimental cardiomyoplasties were performed under the state of normal cardiac function and heart failure. Material and Method: A total of 10 mongrel dogs weighing 20 to 30kg were divided arbitrarily into two groups. Five dogs of group A underwent cardiomyoplasty with latissimus dorsi(LD) muscle mobilization followed by a 2-week vascular delay and 6-week muscle training. Then, hemodynamic studies were conducted. In group B, doxorubicin was given to 5 dogs in an IV dose of 1 mg/kg once a week for 8 weeks to induce chronic heart failure, and simultaneous muscle training was given for preconditioning during this period. Then, cardiomyoplasties were performed and hemodynamic studies were conducted immediately after these cardiomyoplasties in group B. Result: In group A, under the state of normal cardiac function, only mean right atrial pressure significantly increased with the pacer-on(p<0.05) and the left ventricular hemodynamic parameters did not change significantly. However, with pacer-on in group B, cardiac output(CO), rate of left ventricular pressure development(dp/dt), stroke volume(SV), and left ventricular stroke work(SW) increased by 16.7${\pm}$7.2%, 9.3${\pm}$3.2%, 16.8${\pm}$8.6%, and 23.1${\pm}$9.7%, respectively, whereas left ventricular end-diastole pressure(LVEDP) and mean pulmonary capillary wedge pressure(mPCWP) decreased by 32.1${\pm}$4.6% and 17.7${\pm}$9.1%, respectively(p<0.05). In group A, imipramine was infused at the rate of 7.5mg/kg/hour for 34${\pm}$2.6 minutes to induce acute heart failure, which resulted in the reduction of cardiac output by 17.5${\pm}$2.7%, systolic left ventricular pressure by 15.8${\pm}$2.5% and the elevation of left ventricular end-diastole pressure by 54.3${\pm}$15.2%(p<0.05). With pacer-on under this state of acute heart failu e, CO, dp/dt, SV, and SW increased by 4.5${\pm}$1.8% and 3.1${\pm}$1.1%, 5.7${\pm}$3.6%, and 6.9${\pm}$4.4%, respectively, whereas LVEDP decreased by 11.7${\pm}$4.7%(p<0.05). Comparing CO, dp/dt, SV, SW and LVEDP that changed significantly with pacer-on, both under the state of acute and chronic heart failure, augmentation widths of these left ventricular hemodynamic parameters were significantly larger under the state of chronic heart failure(group B) than acute heart failure(group A)(p<0.05). On gross inspection, variable degrees of adhesion and inflammation were present in all 5 dogs of group A, including 2 dogs that showed no muscle contraction. No adhesion and inflammation were, however, present in all 5 dogs of group B, which showed vivid muscle contractions. Considering these differences in gross findings along with the following premise that the acute heart failure state was not statistically different from the chronic one in terms of left ventricular parameters(p>0.05), the larger augmentation effect seen in group B is presumed to be mainly attributed to the viability and contractility of the LD muscle. Conclusion: These results indicate that the positive circulatory augmentation effect of cardiomyoplasty is apparent only under the state of heart failure and the preservation of muscle contractility is important to maximize this effect.

• Environmental Mutagens and Carcinogens
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• v.24 no.1
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• pp.25-32
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• 2004

To validate and to estimate the chemical hazard playa very important role to environment and human health. The detection of many synthetic chemicals used in industry that may pose a genetic hazard in our environment is of great concern at present. Since these substances are not limited to the original products, and enter the environment, they have become widespread environmental pollutants, thus leading to a variety of chemicals that possibly threaten the public health. In this resepct, the clastogenicity of 17 synthetic chemicals was evaluated with bone marrow micronucleus assay in mice. The positive control, mitomycin C (2 mg/kg, i.p.) revealed significant induction ratio of percentage of micronucleated polychromatic erythrocytes/1,000 polychromatic erythrocytes compared to solvent controls. The chemicals with relatively high $LD_{50}$ value such as allyl alcohol (CAS No. 107-18-6), 2,4-pentanedione (CAS No. 123-54-6) and 4-chloro-3,5-dimethylphenol (CAS No. 88-04-0) revealed no significant induction of micronucleated polychromatic erythrocytes in mice. From this results, 17 synthetic chemicals widely used in industry have revealed no significant micronucleus induction of clastogenicity in mice in this experiment.