• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.5
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• pp.315-322
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• 2003

Background : Important factors to determine treatment method and prognosis of oral cancer are anatomical site, tumor size, metastatic lesion, histologic cell differenciation and microvascular invasion. Anatomical site has great effect to oral cancer patient's survival rate because each site's accessibility and lymph node metastasis is different but this factor was't studied much than other factors. Patients and Methods : 228 patients with squamous cell carcinoma of common primary sites(Mandible, Maxilla, Floor of Mouth and Tongue) in oral cavity who were diagnosed in the Korea Cancer Center Hospital from January 1989 to December 1999, were clinically studied and analyzed on survival rate. Results : 1. Survival rates of each anatomical sites were Tongue(36.8%), Mandible(33.3%), Maxilla(28.7%) and Floor of Mouth(24.5%). Survival rates difference between Tongue and Floor of Mouth has significance(p<0.05). 2. Survival rates for early cancer of each site were Maxilla(100%), Mandible(57.1%), Tongue(54.2%) and Floor of Mouth(46.7%). Survival rates difference between Maxilla and Floor of Mouth has significance(p<0.05). 3. Survival rates by surgery method of each site were Maxilla(60.6%), Tongue(56.9%), Mandible(44.8%) and Floor of Mouth(26.3%). Survival rates difference between Maxilla and Floor of Mouth has significance(p<0.05). 4. Survival rates by radiation or chemo method of each site were Floor of Mouth(23.5%), Mandible(20.0%), Maxilla(9.5%), and Tongue(9.1%). Survival rates difference between each site doesn't have significance(p>0.05). 5. In advance stage, Survival rates by single therapy of each site were Tongue(33.6%), Mandible(23.5%), Floor of Mouth(16.7%), Maxilla(0%), and Survival rates difference between Maxilla and Tongue has significance (p<0.05). Survival rates by combination therapy of each site were Mandible(38.1%), Maxilla(30.0%), Floor of mouth(18.2%), Tongue(12.5%), and Survival rates difference between Mandible and Tongue has significance(p<0.05). Conclusion : Survival rate of tongue is higher than the other sites, early detection of oral cancer can increase survival rate at any site and combination therapy is the most effetive method, especially at maxilla.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.4
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• pp.287-293
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• 2001

Objective : To investigate the efficacy of high infusion frequency of liquid nitrogen on pregnancy in human embryo after freezing and thawing. Materials and Methods: 150 infertile patients underwent 162 consecutive thawing-ET cycles. In the high infusion frequency group (Group A), 47 patients (50 cycles) underwent cryopreservation with high infusion frequency of liquid nitrogen. In the low infusion frequency group (Group B), 103 patients (112 cycles) underwent cryopreservation with low infusion frequency of liquid nitrogen. We analyzed the clinical characteristics, fertilization rates, development of embryo, good quality embryo ratio, implantation rates, and pregnancy rates between these two groups. Results: There was no difference between the groups with regard to clinical characteristics (mean age, infertility duration, infertility factors, hormone profile), mean number of oocyte retrieval, fertilization rates, and mean embryo number of transfers. The survival rates in group A was 64.9% (228 of 350 embryos), and among the 228 embryos 190 embryos (83.3%) which progressed to the two- to eight-cell stage. After thawing, the embryo numbers were 65 (34.2%), 29 (15.3%), 35 (18.4%), and 37 (19.5%) of grades 1, 2, 3, and above 4, respectively. The survival rates in group B was 63.8% (482 of 755 embryos), and among the 482 embryos 465 embryos (96.5%) which progressed to the two- to eight-cell stage. After thawing, the embryo numbers were 106 (22.8%), 94 (20.2%), 89 (19.1%), and 112 (24.1%) of grades 1, 2, 3, and above 4, respectively. There was no difference in embryo quality change after the freezing-thawing procedure between the groups. Implantation rates (31.1% vs. 34.3%) were not significant. However hCG positive rates in group A (40%) were higher than group B, but not statistically significant. Clinical pregnancy rate (26% vs. 25.9%), on going pregnancy rates (>20 weeks) were not significant (26% vs. 25%). Conclusion: We compared embryo quality change, survival rates, and pregnancy rates between high infusion frequency group and low infusion frequency group and the results were similar between the two groups. Therefore, high infusion frequency of liquid nitrogen for cryopreservation is a worthy method to preserve in human embryos.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.5
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• pp.92-100
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• 2001

This study was conducted to evaluate the growth rate of landscape trees produced in containers for three year, and the growth rate of the establishment period during sixth month~twelve months after transplanting. Two types of container such as plastic pot(pot) and fabric growing bag(bag) were adopted to restrict tree roots. Each type of container was divided into seven sub-types. One traditional production method was included as comparison. Two landscape woody plant species (Magnolia denudata, Albizzia julibrissin) were planted in the seven sub-types of container. After one or two growing season in the container, the trees of each container type were transplanted. Half of the trees were transplanted in the mild spring season, and the other half were transplanted in the improper summer season. The data was collected on the diameter of root cellar and the tree height in each year. The research results are as follows; 1. Container production method was lower than the traditional production methods by 1.3 times ~ 2 times in the growth rates. 2. The Geocell bag and Root control bag revealed higher growth rates than pp-woven bag. And pot- in-pot(double pot)system revealed higher growth rates than the ether container pot system in A denudata. There were no differences in the growth rates between container production system in Albizzia julibrissin. 3, The growth rates of improper transplanting trees was high in the \"pot\" type - \"bag\" type - \"control\" in descending order. Especially, the growth rates of \"pot\" type revealed higher than \"control\" by 4 times. 4. From the results of ANOVA and Ad hoc test, the variable of growth factors of each container types in improper transplanting experiment was not significant for a range of 5% or 1% level. And the growth rates of traditional production method was lower than the container production method. 5. There was no differences in growth rate between the containerized and the traditional production system in the case of proper transplanting experiment. The growth rates of diameter of root collar was higher in the \"control\". The growth rates of tree height was higher in the \"bag\" type. Finally, based upon the results of this study, subsequent research on the development of container materials and maintaining methods that focused on the growth rates would be required.aintaining methods that focused on the growth rates would be required.

• Ocean and Polar Research
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• v.25 no.3
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• pp.277-286
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• 2003

Nitrification performance of fixed film biofilters using coarse sand, loess bead, or styrofoam beads in biofilter columns 1 meter high and 30cm in diameter were studied at different hydraulic and organic matter loading rates. Synthetic wastewater was supplied to the culture tank in order to maintain desired TAN concentrations in inlet water to biofilters. All the biofilters were conditioned 5 months before start of sampling. TAN and $NO_2-N$ conversion rates increased with an increase in the hydraulic loading rate (HLR). However, the improvement in biofilter performance was not linearly correlated to HLR in styrofoam bead filters. This is mainly due to the characteristics of the styrofoam beads used. TAN conversion rates of sand filters increased with the increase of HLR up to $200m^3/m^2$. per day. No increase in the TAN conversion rate was observed at the highest HLR since flooding on the media surface took place. HLR had a significant impact on the TAN conversion rates in loess bead filter up to the highest HLR tested (P<0.05). TAN conversion rates were much less at organic matter loading rates of 9 and 18kg $O_2/m^3$ per day than those without the addition of organic matter in styrofoam bead filters. The addition of glucose resulted in a reduction of the TAN conversion rate from 540 to 284g $TAN/m^3$ per day. No significant difference of TAN conversion rates between the two organic matter loading rates was found (p<0.05). This indicates that the impact of organic matter on nitrification becomes less and less sensitive with an increase in the COD/TAN ratio. At an organic matter loading rate of 9kg $O_2/m^3$. per day, a great reduction of TAN conversion rates was observed in sand filters and loess bead filters. Clearly, organic matter can be one of the most Important Impacting factors on nitrification. $NO_2-N$ conversion rates showed a similar trend for TAN. Based on the TAN and nitrite conversion rates, styrofoam beads showed the best performance among the three filter media tested. Also, the low gravity and price of styrofoam beads make the handling easier and more cost-effective for commercial application. The results obtained at the highest organic matter loading rates can be used in the biofilter design in recirculating aquaculture system.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.45-50
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• 2007

In this study, uptake rates of internal organs and daily urinary excretion rates were measured to get more reliable estimation results for Korean. Radioactive iodine($^{131}I$) of $100{\mu}Ci$ was administered by ingestion to 28 adult males for the experiment and then the radioactivity in thyroid gland, liver, stomach, small intestine, kidneys, and urine was measured after time intervals of 2, 4, 6 and 24 hours. Uptake rates of each organ and daily urinary excretion rates were calculated on the basis of these experimental results. As a result, uptake rates of 19.70% for thyroid and daily urinary excretion rates of 71.12%, on the average, were indicated. The maximum of uptake rates and daily urinary excretion rates were recorded after 2 hours of administration of $^{131}I$, but those rates were decreased gradually later. It was also found that uptake rates were the highest in stomach, followed by the left kidney, liver, small intestine and right kidney except for thyroid gland. In this experiment, the calculated uptake change rate in thyroid gland after 24 hours of administration of $^{131}I$ was different from that of ICRP-54/67(30%) and ICRP-78(25%). Thus, it is necessary to apply more reliable approach, reflecting the characteristic of Korean physiology and to obtain the basic data of results using this approach for calculation of the internal adsorbed dose. In the future, this approach can be helpful for the internal dose assessment of radiation workers in a nuclear power plant or in a hospital.

• Health Policy and Management
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• v.17 no.3
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• pp.87-105
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• 2007

The purpose of this study was to analyze whether nonemergency, isolated coronary artery bypass graft (CABG) surgery for high- or low-risk patients biases the assessment of the risk-adjusted mortality rates of hospitals. This study used 2002 National Health Insurance claims data for tertiary hospitals in Korea. The study sample consisted of 1,959 patients from 23 tertiary hospitals. The risk-adjustment model used the patients' biological, admission, and comorbidity data identified in the claims. The subjects were classified into high- and low-risk groups based on predicted surgical risk. The crude mortality rates and risk-adjusted mortality rates for low-risk, high-risk, and all patients in a hospital were compared based on the rank and the four intervals defined by quartile. Also, the crude mortality rates of the three groups were compared with their 95% confidence intervals of predicted mortality rates. The C-statistic (0.83) and Hosmer-Lemeshow test ($X^2$=11.47, p=0.18) indicated that the risk-adjustment model performed well. Presenting crude mortality rates with their 95% confidence intervals of predicted rates showed higher agreements among the three groups than using the rank or intervals of mortality rates defined by quartile in the hospital performance assessment. The crude mortality rates for the low-risk patients in 21 of the 23 hospitals were located on the same side of their 95% confidence intervals compared to that for all patients. High-risk patients and all patients differed at only one hospital. In conclusion, the impact of risk selection by hospital on the assessment results was the smallest when comparing the crude inpatient mortality rates of CABG patients with the 95% confidence intervals of predicted mortality rates. Given the increasing importance of quality improvements in Korean health policy, it will be necessary to use the appropriate method of releasing the hospital performance data to the public to minimize any unwanted impact such as risk-based hospital selection.

• Honam Mathematical Journal
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• v.34 no.2
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• pp.209-217
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• 2012

Convergence rates in the law of large numbers for i.i.d. random variables have been generalized by Gut[Gut, A., 1978. Marc inkiewicz laws and convergence rates in the law of large numbers for random variables with multidimensional indices, Ann. Probab. 6, 469-482] to random fields with all indices having the same power in the normalization. In this paper we generalize these convergence rates to the identically distributed and negatively associated random fields with different indices having different power in the normalization.

• Journal of the Korean Data and Information Science Society
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• v.10 no.2
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• pp.445-455
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• 1999

We modify the Gompertz regression model for estimation of cure rates from pediatric clinical trials by assuming different hazard rates on the different periods. A treatment period may be divided by the stages of treatments under the different treatment arms. The piecewise Gompertz models provide an efficient method for estimation of the cure rates and a method for testing the difference of the treatment effects in the given interval.

• The Korean Journal of Financial Studies
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• v.6 no.1
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• pp.335-356
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• 2000

This paper examines the time series dynamics of spot and forward exchange rates and Eurocurrency deposit rates for four bilateral relationships vis a vis the U.S. dollar using daily data. The equilibrium implied by covered interest parity provides a theoretical foundation from which to estimate and analyze the dynamic properties of each system of exchange rates and interest rates. The structural statistical model is identified by relying on the implied cointegration vectors and long-run neutrality restrictions.

• Korean Journal of Animal Reproduction
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• v.11 no.3
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• pp.161-169
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• 1987

This experiment was carried out to investigate the optimal cooling rate and the plunging temperature into liquid nitrogen of the 8-cell hamster embryos. The female hamsters were induced to superovulate by intraperitoneal injection of 30 i.u. PMSG. Embryos were flushed from oviduct and uterine horn. Embryos were frozen and incubated with a modified Dulbecco's phosphate buffered saline, and equilibrated with 1.5M-dimethyl sulfoxide by a 3-step procedure. The cooling rate of samples was 1$^{\circ}C$/min from room temperature to -5$^{\circ}C$ and the samples were seeded at -5$^{\circ}C$. The plunging temperatures into liquid nitrogen were -20, -25, -30, -35, -40, -45, -50 and -55$^{\circ}C$ at 0.3$^{\circ}C$/min, 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. The survival rates at 0.3$^{\circ}C$/min were significantly high. Under the condition of 0.3$^{\circ}C$/min cooling rate, the survival rates of embryos according to the plunging temperature were 70.0% and 73.5% at -40 and -45$^{\circ}C$, and those were higher than other plunging temperatures. Under the condition of 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, the survival rates according to the plunging temperatures were lower than the cooling rate of 0.3$^{\circ}C$/min, showing the similar tendency at all the plunging temperatures. In conclusion, 8-cell hamster embryos showed the best survival rates at 0.3$^{\circ}C$/min cooling rate and -45$^{\circ}C$ plunging temperature.