• Korean Journal of Crystallography
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• v.6 no.1
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• pp.1-13
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• 1995

Cr:A12O3 and Ti:A12O3 single crystals were grown by Czochralski method, and the effects of crystal growth parameters such as pulling rate, rotation rate, dopant and growth atmosphere on crystal quality were investigated. And spectroscopic properties including lasing efficiency were also measured. Single crystals, sized of 20mm in diameter and 100-135mm in length, were successfully grown from the seed of <001> direction. With the doping level of 0.5w/o Cr2O3, pulling rate 2.0mm/hr, rotation rate of 30rpm and inert atmosphere by nitrogen gas, high quality crystals of Cr:A12O3 were grown. While in case of Ti:A12O3 crystals, high quality crystals were grown under the conditions of the doping level of 0.25w/o TiO2, pulling rate of 1.5mm/hr, rotation rate of 30rpm and reducing atmosphere by hydrogen - nitrogen mixed gas. It was confirmed that Cr3+ ion which maintains its ionoc valence during growth easily de-bubbled than Ti4+ ion which changes its valence, Fe3+ ion also has do-bubbling effect to Ti:A12O3 crystal and the reducing atmosphere by 90% N2 - 10% H2 mixed gas gave effective result on the changing of Ti4+ to Ti3+ and de-bubbling. As a result of spectroscopic measurements of Cr:A12O3 crystal, 4A2 →4F2 and 4F1 absorption transitions and E →4A2(R1) and 2A →4A2(R2) fluorenscence transitions were confirmed. And it was measured that wavelengths of laser R1 and R2 transitions were 696±5nm and 692±5nm respectively, line width of these transitions were 12A, and life-time of fluorenscence was 152μsec. In case of Ti:A12O3 crystals, it was confirmed that absortion transition of 4T2→4E and fluorescence transition of 4E→4T2 with wide range of 650-1050nm was occured. And 147μsec of life-time of fluorescence, 125.4 of figure of merit and 9% of laser efficience were also measured.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.125-133
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• 1995

The crystal structure of dehydrated, partially Co(II)-exchanged zeolite X, stoichiometry Co2+Na+-X (Co41+Na10Si100Al92O384) per unit cell, has been determined from three-dimensional X-ray diffraction data gathered by counter methods. The structure was solved and refined in the cubic space group Fd3:α=24.544(1)Å at 21(1)℃. The crystal was prepared by ion exchange in a flowing stream using a solution 0.025 M each in Co(NO3)2 and Co(O2CCH3)2. The crystal was then dehydrated at 380℃ and 2×10-6 Torr for two days. The structure was refined to the final error indices, R1=0.059 and R2=0.046 with 211 reflections for which I > 3σ(I). Co2+ ions and Na+ ions are located at the four different crystallographic sites. Co2+ ions are located at two different sites of high occupancies. Sixteen Co2+ ions are located at the center of the double six-ring (site I; Co-O = 2.21(1)Å, O-Co-O = 90.0(4)°) and twenty-five Co2+ ions are located at site II in the supercage. Twenty-five Co2+ ions are recessed 0.09Å into the supercage from its three oxygen plane (Co-O = 2.05(1)Å, O-Co-O = 119.8(7)°). Na+ ions are located at two different sites of occupandies. Seven Na+ ions are located at site II in the supercage (Na-O = 2.29(1)Å, O-Na-O = 102(1)°). Three Na+ ions are statistically distribyted over site III, a 48-fold equipoint in the supercages on twofold axes (Na-O = 2.59(10)Å, O-Na-O = 69.0(3)°). Seven Na+ ions are recessed 1.02Å into the supercage from the three oxygen plane. It appears that Co2+ ions prefer sites I and II in order, and that Na+ ions occupy the remaining sites, II and III.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.8-19
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• 1996

Cholestryl Methyl and Propyl Carbonate(CH3OCOOC27H45, C3H7OCOOC27H45) are monoclinic, space group P21, with a=17.014(1), b=7.682(1), c=10.612(1)Å, β=103.05(1)°, Z=2, V=1351.16Å3, Dc=1.09 g/cm3 for methyl carbonate, and with a=13.683(1), b=11.864(2), c=18.904(2)Å, β=106.30(1)°, Z=4, V=2945.4Å3, Dc=1.06 g/cm3, Dm=1.06 g/cm3 for propyl carbonate. The intensity data were collected on an Enraf-Nonius CAD-4 diffractometer with a graphite monochromated Cu-Kα radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R factor was 0.051 for 2323 observed reflections for methyl carbonate and 0.074 for 3323 observed reflections for propyl carbonate. Compared with other cholesteryl derivatives, the cholesteryl ring and tail region of the molecules are normal. The molecules are stacked in clearly separated layers. At center of the layer, there are cholesteryl-C(17) side chain interactions. The interface region between layers is occupied by the loosely packed methyl carbonate chains. The structure of cholesteryl propyl carbonates have two propyl carbonates have two molecules(A, B) that are not related by crystal symmetry and have their tetracyclic system almost parallel to each other. Cholesteryl-cholesteryl interactions between symmetry related A-molecules, and cholesteryl-C(17) side chain interactions between symmetry related B-molecules occur at the center of the layers and these molecules stack along 2₁ screw axes. There are also C(17)chain-carbonate chain and C(17)chain-C(17)chain interactions in the interface region between layers. There is efficient packing between cholesteryl ring systems in propyl carbonates. Temperature ranges of cholesteric mesophases of cholesteryl alkyl cargonates are narrow for methyl, pentyl and hexyl carbonates, and rather broader for ethyl and propyl carbonates. Cholesteryl-isotropic transitions change very little with chain length.

• Sleep Medicine and Psychophysiology
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• v.9 no.2
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• pp.106-114
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• 2002

Objectives: Daytime sleepiness is a common symptom and is associated with sleep behavior, sleep deprivation, and night shift, etc. It is also one of the most important symptoms of sleep disorders like obstructive sleep apnea (OSA). According to our survey on Korean literature, a few studies have dealt with daytime sleepiness, and we have not been able to locate any study comparing normal subjects with polysomnography-proven sleep disorder patients regarding daytime sleepiness. We aimed at comparing daytime sleepiness among normal healthy daytime workers, medical students being expected to have daytime sleepiness due to chronic sleep deprivation, and patients having sleep disorders diagnosed with polysomnography. We also studied the association between subjective daytime sleepiness and objective polysomnographic findings in patients with sleep disorders. Methods: One hundred three hospital workers, 137 medical students, and patients with sleep disorders were studied. Sleep disorders included OSA, periodic limb movements in sleep (PLMS), insomnia, and narcolepsy. The degree of subjective sleepiness in each group was measured by the Korean version of Epworth sleepiness scale and compared. The relationship between polysomnographic findings reflecting severity of sleep disorder in each patient group and subjective sleepiness was analyzed. As for patients with narcolepsy, the relationship between the mean sleep latency and subjective sleepiness was studied. Results: There was a significant difference of ESS score (F=68.190, dF=5.752, p<0.001) among daytime workers, medical students, and sleep disorder patients. In OSA patient group, the degree of the sleepiness had no significant correlation either with mean O2 satuaration (p=0.062) or with RDI (p=0.807). In PLMS patient group, there was no correlation between periodic limb movement index (PLMI) and subjective sleepiness (p=0.761). In narcolepsy patient group, the subjective sleepiness had no correlation with mean sleep latency measured with MSLT (p=0.055). Conclusion: We found a significant difference of subjective sleepiness among daytime workers, medical students, and patients with sleep disorders. However, no consistent correlation was found between severity of subjective sleepiness and objective polysomnographic findings reflecting severity of each sleep disorder. This research confirms that the evaluation of subjective sleepiness is important clinically, but it cannot substitute the objective measures such as nocturnal polysomnography and MSLT.

• Tuberculosis and Respiratory Diseases
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• v.42 no.5
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• pp.752-759
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• 1995

Background: Bronchial asthma is characterized by noctunal dyspnea, cough and wheezing because of airway hyperresponsiveness to nonspecific stimuli. These symptoms and signs are also observed in patients with congestive heart failure. Therefore, this is so called "cardiac asthma". There are lots of experimental and clinical datas to suggest that airway dysfunctions occur in acute and chronic congestive heart failure. However, it is still controversial whether bronchial hyperresponsiveness is present in patients with congestive heart failure. To assess whether bronchial hyperresponsiveness is present in patients with congestive heart failure and to demonstrate the relationship between bronchial responsiveness and vascular pressure, we performed methacholine provocation test in 11 patients with mitral valvular heart disease. Methods: All patients were in the New York Heart Association functional class II and treated continuously with digoxin and/or dichlozid and/or angiotensin converting enzyme inhibitor except one patient. All patients were undergone right and left side heart catheterization for hemodynamic measurements. A 20 percent fall of peak expiratory flow rate were considered as positive response to methacholine provocation test. Results: 1) Only one patient who has normal pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac index was positive in methacholine provocation test. 2) Their mean pulmonary artery pressure, pulmonary capillary wedge pressure were $21.72{\pm}9.70mmHg$, $15.45{\pm}8.69mmHg$ respectively which were significantly higher. Conclusion: It is speculated that in stable congestive heart failure patients, bronchial responsiveness as assessed by methacholine provocation test may not be increased.

• Tuberculosis and Respiratory Diseases
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• v.52 no.2
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• pp.117-127
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• 2002

Backgroud : MUC1 mucin is a heavily glycosylated large glycoprotein and is expressed aberrantly in carcinoma. CD44 is polymorphic family of cell surface glycoproteins participating in cell-cell adhesion and modulation of the cell-matrix interaction. MUC1 mucin and CD44 expression have been implicated in a tumor invasion and metastasis in certain malignancies. In this study, the expression of MUC1 and the standard form of CD44 (CD44s) was examined in non-small cell lung cancer (NSCLC). Methods : Immunohistochemical staining using monoclonal antibodies including MUC1 glycoprotein and CD44s was performed on 80 NSCLC surgical specimens. The association between MUC1 and CD44s expression and the histological type and tumor stage was investigated. Results : Depolarized MUC1 expression in more than 10% of cancer cells was found in 12 (27.9%) out of 43 squamous cell carcinomas (SCCs) and 12 (32.4%) out of 37 adenocarcinomas (ACs). It was not associated with the tumor histological type and the TNM-stage in SCCs. Depolarized MUC1 expression correlated with the N-stage in ACs (p=0.036). CD44s was expressed in 36 (83.7%) out of 43 SCCs and 14 (37.8%) out of 37 ACs. Reduced CD44s expression correlated with the N-stage (p=0.031) and the TNM-stage (p=0.006) in SCCs. Conclusions : Depolarized MUC1 expression was related to the nodal stage in NSCLC adenocarcinoma. Reduced CD44s expression was related to nodal involvement and the TNM-stage in squamous cell carcinoma. This suggests that MUC1 and CD44s expression in NSCLC might play important roles in tumor progression and cap be used as prognostic variables.

• Tuberculosis and Respiratory Diseases
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• v.52 no.1
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• pp.5-13
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• 2002

Background: DNA repair plays a crucial role in protecting the genome from cancer-causing agents. Therefore, a reduced DNA repair capacity can increase the susceptibility to cancer. The human OGG1 (hOGG1) gene encodes DNA glycosylase/apurinic lyase and excise 8-hydroxyguanine, one of the major premutagenic DNA lesions, which is produced by oxygen radical forming agents including smoking. Recently several polymorphisms in the hOGG1 gene were identified, and it is possible that these polymorphism') may affect the DNA repair capacity and thus modulate cancer susceptibility. The relationship between the codon 326 polymorphism (Ser to Cys) in the hOGG1 gene and lung cancer risk was investigated. Materials and Method: The Ser326Cys genotypes were determined using PCR-RFLP analysis in 299 primary lung cancer patients and 186 healthy controls who were frequency (case:control=3:2) matched according to age and sex. Result: The frequencies of the Ser326Cys genotypes (Ser/Ser, Ser/Cys and Cys/Cys) among cases (23.4%, 51.8%, and 24.7%, respectively) were not significantly different from those among the controls (22.6%,52.1% and 25.3%, respectively). When the analyses were stratified according to age, sex, smoking status and packyears of smoking, no significant association between this polymorphism and lung cancer risk was found. Moreover, the Ser326Cys genotype showed no apparent relationship with any of the histological types of lung cancer. Conclusion: These result suggest that the hOGG1 Ser326Cys polymorphism is not a major contributor to individual lung cancer susceptibility in Koreans.

• Particle and aerosol research
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• v.11 no.3
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• pp.63-75
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• 2015

Atmospheric environment in Korea is influenced by outside, especially China. The concentrations of air pollutants in China have showed decreasing trends since 2000. However, these concentration levels in China are still higher than other developed countries. The Chinese Government has tried several measures to control the air pollution. In this study, the details of the amendments and smog reduction strategies in China, especially for Beijing are reviewed and the strategies for Korean side to promote cooperation in Northeast Asia are suggested and discussed. The Chinese State Council amended the Environmental Protection Provisions and Clean Air Act and announced The Action Plan for Air Pollution Control (2013-2017), focusing on three key regions, Beijing-Tianjin-Hebei area (Jing-Jin-Ji), Yangtze River Delta (YRD) and Pearl River Delta (PRD). These policy actions and plan are mainly for the reducing coal usage and emissions from vehicles. It is suggested that, Korea should actively promote multi-national cooperation in the region to take an initiative role in environmental areas.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.96-108
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• 1985

A study for the assessment of natural environmental radiation exposure at a flat and open field of about $10,000m^2$ in area in CNU Daeduk campus has been carried out by means of gamma-ray scintillation spectrometry and thermoluminescence dosimetry for one year period of time from October 1984. The detectors used were 3'${\phi}{\times}$3' NaI(T1) and two different types of LiF TLD, namely, chip sealed in plastic sheet which tightly pressed on two open holes of a metal plate and Teflon disk. Three 24-hour cycles of in-situ spectrometry, and two 3-month and one 1-month cycles of field TL dosimetry were performed. All the spectra measured were converted into exposure rate by means of G(E) opertaion, and therefrom exposure rate due to terrestrial component of environmental radiation was figured out. Exposure rate determined by the spectrometry was, on average, $(10.54{\pm}2.96){\mu}R/hr$, and the rates of $(12.0{\pm}3.4){\mu}R/hr$ and $(11.0{\pm}3.6){\mu}R/hr$ were obtained from chip and disk TLD, respectively. Fluctuations in diurnal variation of the exposure rate measured by the spectrometry were noticeable sometime even in a single cycle of 24 hours. It is concluded that appropriately combined use of TLD with iu-sitn gamma-ray spectrometry system can give more accurate and precise measure of environmental radiation exposure, and further study for more adequate and sensitive TLD for environmental dosimetry, including improvement and elevation of accuracy in data assessment through inter-laboratory or international intercomparison is necessary.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.1-7
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• 2005

Radiation absorption parameters of carbon fiber panel were measured in comparison to acrylic panel. $30{\times}30cm$ sized 2mm thick carbon fiber panel and identical sized 6mm thick acrylic panel were placed in tray holder position and 0cm, 5cm, 10cm from surface of phantom. Radiation field size was $10{\times}10cm$. 50MU of 4MV photon was irradiated to the phantom with dose rate of 300MU/min. Source-to-phantom distance was 120cm. Radiation dose was measured with 0.6cc Farmer-type ionization chamber with 1cm build-up. Measurement was repeated thrice and normalization was done to the dose of the open field. Radiation transmission rate of carbon fiber panel is approximately 1% lower than acrylic panel of equivalent thickness. However, considering the strength of the material, transmission rate is higher for carbon fiber panel. Although carbon fiber panel increases the radiation dose when attached to the surface for about 2%, it normalizes the radiation dose to 97-99% of irradiated dose which could have been lowered to as much as 5-7.5% with acrylic panel. As carbon fiber panel is stronger than acrylic panel, radiation fixation device could be made thinner and thus lighter and furthermore, with increased radiation transmission. This in turn makes carbon fiber more ideal material for radiation fixation device over conventionally used acrylic.