• The Korean Journal of Nuclear Medicine
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• v.37 no.4
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• pp.219-228
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• 2003

Purpose: The amount of salvaged myocardium is an important prognostic factor in patients with acute myocardial infarction (MI). We investigated if early Tl-201 SPECT imaging could be used to predict the salvaged myocardium and functional recovery in acute MI after primary PTCA. Materials and Methods: In 36 patients with first acute MI treated with primary PTCA, serial echocardiography and Tl-201 SPECT imaging ($5.8{\pm}2.1$ days after PTDA) were performed. Regional wall motion and perfusion were quantified with on 16-segment myocardial model with 5-point and 4-point scaling system, respectively. Results: Wall motion was improved in 78 of the 212 dyssynergic segments on 1 month follow-up echocardiography and 97 on 7 months follow-up echocardiography, which were proved to be salvaged myocardium. The areas under receiver operating characteristic curves of Tl-201 perfusion score for detecting salvaged myocardial segments were 0.79 for 1 month follow-up and 0.83 for 7 months follow-up. The sensitivity and specificity of Tl-201 redistribution images with optimum cutoff of 40% of peak thallium activity for detecting salvaged myocardium were 84.6% and 55.2% for 1 month follow-up, and 87.6% and 64.3% for 7 months follow-up, respectively. There was a linear relationship between the percentage of peak thallium activity on early redistribution imaging and the likelihood of segmental functional improvement 7 months after reperfusion. Conclusion: Tl-201 myocardial perfusion SPECT imaging performed early within 10 days after reperfusion can be used to predict the salvaged myocardium and functional recovery with high sensitivity during the 7 months following primary PTCA in patients with acute MI.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.39-45
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• 2022

This study aimed to investigate the validation and modify the analytical method to determine quercetin-3-𝑜-gentiobioside and isoquercitrin in Abelmoschus esculentus L. Moench for the standardization of ingredients in development of functional health products. The analytical method was validated based on the ICH (International Conference for Harmonization) guidelines to verify the reliability and validity there of on the specificity, linearity, accuracy, precision, detection limit and quantification limit. For the HPLC analysis method, the peak retention time of the index component of the standard solution and the peak retention time of the index component of A. esculentus L. Moench powder sample were consistent with the spectra thereof, confirming the specificity. The calibration curves of quercetin-3-𝑜-gentiobioside and isoquercitrin showed a linearity with a near-one correlation coefficient (0.9999 and 0.9999), indicating the high suitability thereof for the analysis. A. esculentus L. Moench powder sample of a known concentration were prepared with low, medium, and high concentrations of standard substances and were calculated for the precision and accuracy. The precision of quercetin-3-𝑜-gentiobioside and isoquercitrin was confirmed for intra-day and daily. As a result, the intra-day precision was found to be 0.50-1.48% and 0.77-2.87%, and the daily precision to be 0.07-3.37% and 0.58-1.37%, implying an excellent precision at level below 5%. As a result of accuracy measurement, the intra-day accuracy of quercetin-3-𝑜-gentiobioside and isoquercitrin was found to be 104.87-109.64% and the daily accuracy thereof was found to be 106.85-109.06%, reflecting high level of accuracy. The detection limits of quercetin-3-𝑜-gentiobioside and isoquercitrin were 0.24 ㎍/mL and 0.16 ㎍/mL, respectively, whereas the quantitation limits were 0.71 ㎍/mL and 0.49 ㎍/mL, confirming that detection was valid at the low concentrations as well. From the analysis, the established analytical method was proven to be excellent with high level of results from the verification on the specificity, linearity, precision, accuracy, detection limit and quantitation limit thereof. In addition, as a result of analyzing the content of A. esculentus L. Moench powder samples using a validated analytical method, quercetin-3-𝑜-gentiobioside was analyzed to contain 1.49±0.01 mg/dry weight g, while isoquercitrin contained 1.39±0.01 mg/dry weight g. The study was conducted to verify that the simultaneous analysis on quercetin-3-𝑜-gentiobioside and isoquercitrin, the indicators of A. esculentus L. Moench, is a scientifically reliable and suitable analytical method.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.101-118
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• 2023

During the COVID-19 pandemic, the utilization rate of neighborhood parks and green spaces increased significantly, and the outbreak served as an opportunity to highlight the values and functions of neighborhood parks and green spaces for urban residents. This study aims to empirically analyze how citizens' movement and the use of neighborhood parks and green spaces changed before and after COVID-19 and examine the social and spatial characteristics that affected these changes. As a research method, first, people's mobility around neighborhood parks and green spaces before and after the COVID-19 pandemic were compared using signal data from telecommunication carriers. Through the analysis of changes in residence time and movement volume, the movement characteristics of citizens after COVID-19 and changes in walking-based park visits were examined. Second, the factors affecting the mobility change in neighborhood parks and green spaces were analyzed. The social and spatial characteristics that affect citizens' visits to neighborhood parks and green spaces before and after COVID-19 were examined through correlation and multiple regression analysis. Subsequently, through cluster analysis, the types of living areas for the post-COVID era were classified from the perspective of the supply and management of neighborhood parks and green spaces services, and directions for improving neighborhood parks and green spaces by type were presented. Major research findings are as follows: First, since the outbreak of COVID-19, activities within 500m of the residence have increased. The amount of stay and walking movement increased in both 2020 and 2021, which means that the need to review the quantitative standards and attractions of neighborhood parks and green spaces has increased considering the changed scope of the walking and living area. Second, the overall number of visits to neighborhood parks and green spaces by walking has increased since the outbreak of COVID-19. The number of visits to neighborhood parks and green spaces centered on the house and the workplace increased significantly. The park green policy in the post-COVID era should be promoted by discovering underprivileged areas, focusing on areas where residential, commercial, and business facilities are concentrated, and improving neighborhood parks and green services in quantitative and qualitative terms. Third, it was found that the higher the level of park green service, the higher the amount of walking movement. It is necessary to use indicators that contribute to improving citizens' actual park green services, such as walking accessibility, rather than looking at the criteria for securing green areas. Fourth, as a result of cluster analysis, five types of neighborhood parks and green spaces were derived in response to the post-COVID era. This suggests that it is necessary to consider the socioeconomic status and characteristics of living areas and the level of park green services required in future park green policies. This study has academic and policy significance in that it has laid the basis for establishing neighborhood parks and green spaces policy in response to the post-COVID era by using various analysis methodologies such as carrier signal data analysis, GIS analysis, and statistical analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.3
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• pp.49-82
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• 1965

For the stable and high yields of low-land rice in Korea, the characteristics of rice plant for the vegetative and physiological responses, plant type formation, and yield components have been studied in order to obtain the fundamental data for the improvement of cultural practices, especially for the ideal fertilizer application. Furthermore the environmental conditions in Korea including temperatures, light, precipitation, and soil conditions have been compared in the broad sense with those in Japan, and the application of nitrogen, phosphorus, potassium, silicate and other micro-nutrients were described in relation to the characteristics of environmental conditions for the improvement of fertilizer application. 1. The average yield of polished-rice per 10 are in Korea is about 204 kg and this values are much less than those in Japan and Taiwan where they produce 77% to 13% more than in Korea. The rate of yield increase a year in Korea is 4.2 kg, but in Japan and Taiwan the rates of yield increase a year are 81 % and 62%, respectively. It was also found that the coefficient of variation of yield is 7.7% in Korea, 6.7% in Japan and 2.5% in Taiwan. This means that the stability of producing rice in Korea is very low when compared with those in Japan and Taiwan. 2. It was learned from the results obtained from the 'annual yield estimation experiment' that there are big differences in the respect of plant type formations between rice crops grown in Japan and Korea. The important differences found were as follows: (1) The numbers of spikelets per 3.3 square meters are 891 in Korea and 1, 007 in Japan(13% more than in Korea). (2) The numbers of tillers per 3.3 square meters at the stage of maximum tillering are 1, 150 in Korea, but in Japan they showed 19% more than in Korea. (3) The ratio of effective tillers to total tillers is 77.5% in Korea and 74.7% in Japan, which seems to be higher in Korea than in Japan. But the ratio in Korea is very low when considered the numbers of total tillers in both countries. (4) The ratio of grain to straw is 85.4% in Korea and 96.3% in Japan. 3. The average temperatures during the growing season at the area of Suwon, Kwangjoo and Taegu are almost same as those in the district of Jookokoo(Fookoo yama) in Japan, i.e., the temperatures during the rice-growing season in Korea are similar to those in the southern-warm regions of Japan. 4. Considering the minimum temperatures at the stage of limiting transplanting, 13$^{\circ}C$, the time of transplanting might be 30 to 40 days earlier than presently practicing transplanting time, which comes around June 10. 5. The temperatures during the vegetative growth in Korea were higher than those temperatures that needed in the protein synthesis which ate the main metabolism during this stage. However, the temperatures at the time of reproductive growth was lower than the temperatures that needed in the sugar assimilation which is main metabolism in this stage. In this point of view, it might be considered that the proper time of growing rice plant in Korea would be rather earlier. 6. The temperatures and the day light conditions at the time of first tillering stage of rice plant, when planted as presenting transplanting practices, are very satisfactory, but the poor day light length, high temperatures and too wet conditions in the time of last-tillering stage(mid or last July) might cause the occurrence of disease such as blast. 7. The heading stage of rice plants at each region through nations when planted as presently practicing method comes when the day light length is short. 8. It was shown that the accumulated average air-temperature at the time of maturing stage was not enough and the heading time was too late, when considered the annual deviations of mean temperatures and low minimum temperatures. 9. The nitrogen content of each plant part at the each growing stage was very high at the stage of vegetative growth when compared with the nitrogen content at the stage of reproductive growth after heading. In this respect it was believed to be important to prevent the nutrient shortages at the reproductive stages, especially after the heading. 10. The area of unsatisfactory irrigation paddy fields and natural rain-fed paddy fields are getting reduced in Korea. The correlation between the rate of reducing unsatisfactory irrigation and natural rain-fed paddy fields and the rate of yield increase were computed. The correlation coefficients(r) between the area of unsatisfactory irrigation paddy fields and yield increase were +0.525, and between the natural rain-fed paddy fields and yield increase, +0.832 and between the unsatisfactory irrigation plus natural rain-fed paddy fields and yield increase, +0.84. And there were. highly significant positive correlations between natural rain-fed paddy fields and yield increases indicating that the less the area of natural rain-fed paddy fields, the greater the yields per unit area. 11. The results obtained from the fertilizer experiments (yield performance trials) conducted in both Korea and Japan showed that the yield of non-fertilized plots per 10 are was 231 kg in Korea and 360 kg in Japan. On the basis of this it might be concluded that the fertility of soil in Korea is lower than that in Japan. Furthermore it was. also found that the yields of non-nitrogen applied plots per 10 are were 236 kg in Korea and 383 kg in Japan. This also indicates that the yields of rice in Korea are largely depending on the nitrogen content in the soil. 12. The followings were obtained when the chemical natures of soils in both Korea and Japan were compared. (1) The content of organic matter, total nitrogen, exchangeable calcium, and magnesium in Korea were no more than the half those in Japan. (2) The content of N/2 chloride and soluble silicate in low-land soil were on the average lower in Korea. (3) The exchange capacity of bases in Korea was no more than half that in Japan. 13. It was also observed by comparing the soil nature of the soil with high yielding capacity with the soil with low yielding capacity that the exchange capacity of bases, exchangeable calcium and magnesium, potassium, phosphorus, manganese, silicate and iron were low in the soil with low yielding capacity. 14. The depth of furrow slice was always deeper in the soil with high yielding capacity, and the depth of furrow slice in Korea was also shallower than that in Japan. 15. Summarizing the various conditions mentioned previously and considering the effects of silicate and trace elements such as manganese and iron besides three elements on the physiological and plant type formation of rice crops, more realistic and more ideal fertilizing practices were proposed. proposed.

• Journal of Veterinary Clinics
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• v.24 no.4
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• pp.514-521
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• 2007

The sympathetic nerve block improves the blood flow in the innervated regions. For this region, the sympathetic nerve block has been performed in the neural and cerebral disorders. However, the cerebral blood flow regulation of the cranial cervical ganglion block in dogs have not been well defined and the correlation to the changes in the cerebral circulation and the changes in the electroencephalogram is not well defined in dogs yet. Therefore, we investigated the hypothesis that changes in the EEG could be affected by the changes in cerebral blood flow following the cranial cervical ganglion block in dogs. Twenty five beagle dogs were divided into 3 groups; group I(LCCGB, n=10) underwent left sided cranial cervical ganglion block using the 1% lidocaine, group II(L, n=10) injected the 1% lidocaine into the right or left sided digastricus muscle, group III(N/SCCGB, n=5, served as control) underwent the left sided cranial cervical ganglion block using saline. A statistical difference was not found between the control group and the LCCGB group in the 95% spectral edge frequency(SEF) and the median frequency(MF). In the relative band power, the $\delta$ frequency was decreased during 5-25 min, while the $\alpha$ frequency was increased during the same time(p<0.05). But the $\theta$ frequency and the $\beta$ frequency were not shown the significant changes compared with the control group during the same time(p<0.05). These results suggest that the left cranial cervical ganglion block does not induce the change of the cerebral blood flow and its effect is insignificant.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.153-154
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• 2003

운동여부와 운동횟수 그리고 어체 크기에 대한 양식산 어종의 품질판정을 위한 지표를 검색하기 위하여 효소적 방법 즉 ATP 관련화합물과 양식산 활어의 건강한 상태와 칼슘의 노출, 염도의 감소, 산소의 부족, 궁핍 등과 같은 스트레스를 받은 상태를 판단하는 adenylate energy charge (AEC)를 근육의 품질판정을 위한 지표로써 조사하였다. 운동사육구와 비운동사육구에서의 참돔육에 대한 ATP 관련화합물의 변화는 운동 0일에는 ATP함량은 8.62 μmol/g이었지만 20일차에는 8.59 μmol/g으로 운동기간이 길어짐에 따라 ATP의 함량은 약간의 감소를 보였다. 이는 운동이라는 자극요인으로 인하여 ATP의 소모가 촉진되었을 것으로 판단된다. 또한 운동 0일차의 ADP함량은 0.72 μmo1/g이었지만 20일차에는 0.93μmol/g로 ATP의 소모만큼 약간의 증가를 보이고 있다. 반면, 비운동사육구에서 0일차의 ATP함량은 5.78 μmol/g이었지만 20일차에서는 6.31 μmol/g로 운동사육구와 대조적으로 기간이 길어짐에 따라 ATP함량이 약간의 증가를 보여주고 있다. 생리적으로 동물에 가혹한 환경에 두거나 스트레스를 가하면 adenylate energy charge (AEC)가 영향을 받아 변화게 된다. AEC는 (ATP ＋ ½ ADP)/(ATP ＋ ADP + AMP)의 비율로 정의되는데, AEC의 범위는 0∼1사이로써 0은 ATP 관련화합물이 AMP로 전환된 상태를 말하며, 1은 모든 ATP 관련 화합물이 ATP로 존재하는 것을 의미한다. 그러므로, 이들결합의 상관적인 정도는 개개의 세포에서 에너지의 효용성을 측정하는 것으로 이용되고 있다. AEC 수치는 운동수조에서 0.91∼0.92 건강상태가 좋았지만 비운동수조는 0.87∼0.88로 운동수조에 비해 값이 낮게 나왔다. 운동횟수에 관계없이 운동시킨 어육의 AEC는 0.90∼0.91로 건강한 상태였다. 어체크기에 따른 ATP 관련화합물의 변화는 0.7∼0.9kg의 크기를 가진 참돔에서는 ATP 함량이 7.88 μmole/g, 1.5∼l,7kg의 크기를 가진 참돔에서는 ATP함량이 9.61μmole/g로 많았고 다른 크기에서는 큰 차이를 나타내지 않았다. 그리고 ADP함량은 어체의 크기가 증가할수록 함량은 감소하였다. 그러나, 어체의 크기에 따른 ATP관련화합물의 변화는 거의 없었다. 건강도의 지표인 AEC는 0.89∼0.94로 전체적으로 건강상태로 나타났다. 하루 2회 운동시킨 육에서의 ATP함량은 0일차에 8.75 μmole/g, 10일차에 8.46 μmole/g, 20일차에 8.51μmole/g로 약간의 감소를 보여준다. ADP함량은 일까지는 증가하지만 그 이후에는 큰 변화를 보이지 않는다. 6시간 운동시킨 그룹의 ATP함량은 0일차에 8.63 μmole/g, 5일차에 8.52 μmole/g, 10일차에 8.4μmole/g, 20일차에 8.51 μmole/g로 10일까지는 감소하지만 그 이후에는 큰 변화를 보이지 않는다. ADP함량은 0일차에 0.72 μmole/g, 10일차 0.84 μmole/g, 20일차에 0.83 μmole/g으로 10일차까지는 약간 증가하지만 그 이후에는 큰 변화를 보이지 않았다. 참돔의 근원섬유에 있어서 Ca/sup 2+/이 존재할 때 Mg/sup 2+/-ATPase 활성의 변화는 운동시킨 참돔 근원섬유의 Mg/sup 2+/-ATPase 활성은 0.35μmol Pi/minㆍmg였으며, 비운동구에서 0.34μmol Pi/minㆍmg으로 운동시킨 참돔의 육에서 ATPase 활성이 약간 높은 것으로 나타났다. 운동사육시킨 참돔은 운동기간이 증가할수록 ATPase활성이 증가하여 운동 20일에는 0.42μmo1 Pi/minㆍmg의 함량을 나타내었으나, 비운동사육에서는 큰 차이를 보이지 않고 있다. 근원섬유의 Ca/sup 2+/가 첨가되지 않았을때의 Mg/sup 2+/-ATPase 활성을 나타내었다. 운동시키전에는 각각 0.10μmol Pi/minㆍmg, 0.14μmol Pi/minㆍmg 나타나 비운동구가 운동구에 비하여 Mg/sup 2+/(-Ca/sup 2+/)-ATPase 활성이 높았으며 사육기간동안 활성이 서서히 감소하는 경향을 나타내었다. Ca/sup 2+/-ATPase의 활성 또한 사육기간 동안 큰 변화를 보이지 않았다. 그러므로, 참돔의 운동여부에 따라서 ATPase활성을 살펴본 결과, 운동기간에 따른 약간의 차이는 보이고 있으나, 품질지표로써 사용하기가 어렵다고 판단된다. 효소적인 방법을 이용한 양식산 활어의 품질지표로써 ATP 관련화합물, ATPase 활성은 운동여부, 크기에 따라 객관적인 지표로써의 사용이 어려우므로, 건강도를 측정할 수 있는 AEC의 수치를 적용하는 것이 적합하다고 판단된다. 즉, 양식산 참돔의 AEC 수치가 1∼0.9의 범위에서는 건강한 활어로 상급의 등급을, 0.8∼0.7의 AEC 수치는 중급의 등급으로, 그 이하의 수치에서는 하급으로 적용가능 하다고 판단된다.

• Korean journal of food and cookery science
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• v.1 no.1
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• pp.74-81
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• 1985

For this research, the Atka-fisher which are used commonly in many homes for baking and broilling were broiled by an iron baking method, a pan baking method, a grill baking method and a microwave baking method respectively after 20 hours salting with 3% salt concentration of fish muscle weight. This thesis has an intention of appreciating the tastes according to each baking method through a sensory test, of examining the corelation between the change of texture measured by Rheometer and a sensory test and of comparing the changes of chemical component of the fish. The results were as follow: 1. The appearance of the broiled Atka-fish maintained a good appearance by the iron baking method and the grill baking method. In the color, the iron baking method and the grill baking method by direct :fire resulted a good score too. In the flavor, there was a significant difference between the grill baking method and the microwave baking method while there was no difference between the iron baking method and the pan baking method. The result of tenderness showed that the pan baking method has the highest score. Difference between the iron baking method and the pan baking was not significant. There was no difference in tenderness between the grill baking method and the microwave baking method. The iron baking method showed-the highest score in juciness and the microwave baking method stowed the highest score in acceptability however the differences were not significant. 2. As a result of the measurement of the texture by Rheometer, the iron baking method and the grill baking method showed higher score than other methods in hardness and chewiness. In springiness and cohesiveness, there was no significant difference among methods. As a result of the measurement of the texture by Rheometer, the corelation with a sensory test was considered to be low. 3. After broil, the cooking retention was the highest in the pan baking method and the moisture content was the highest in microwave baking method. Nitrogen content was the highest in the iron baking method. Fat content was the highest in the iron baking method, followed by the grill baking method, the pan baking method, and the microwave baking method. Free amino acid content was the highest in the iron baking method, followed by the grill baking method, the pan baking method and the micro-wave baking method.

• Tuberculosis and Respiratory Diseases
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• v.56 no.6
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• pp.600-610
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• 2004

Background : The plasma B-type natriuretic peptide(BNP) concentration increases with the degree of pulmonary hypertension in patients with chronic respiratory disease. The aim of this study was to examine the prognostic role of BNP in the acute exacerbation of chronic obstructive lung disease (COPD). Method : We selected 67 patients who were admitted our hospital because of an acute exacerbation of COPD. Their BNP levels were checked on admission at the Emergency Department. Their medical records were analyzed retrospectively. The patients were divided into two groups according to their in-hospital mortality. The patients' medical history, comobidity, exacerbation type, blood gas analysis, pulmonary function, APACHE II severity score and plasma BNP level were compared. Results : Multiple logistic regression analysis identified three independent predictors of mortality: $FEV_1$, APACHE II score and plasma BNP level. The decedents group showed a lower $FEV_1$($28{\pm}7$ vs. $37{\pm}15%$, p=0.005), a higher APACHE II score($22.4{\pm}6.1$ vs. $15.8{\pm}4.7$, p=0.000) and a higher BNP level ($201{\pm}116$ vs. $77{\pm}80pg/mL$, p=0.000) than the sSurvivors group. When the BNP cut-off level was set to 88pg/mL using the receiver operating characteristic curve, the sensitivity was 90% and the specificity was 75% in differentiating between the survivors and decedents. On Fisher's exact test, the odds ratio for mortality was 21.2 (95% CI 2.49 to 180.4) in the patients with a BNP level > 88pg/mL. Conclusion : The plasma BNP level might be a predictor of mortality in an acute exacerbation of COPD as well as the $FEV_1$ and APACHE II score.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.173-185
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• 2015

This study aims to investigate the characteristics and types of car accidents and establish a prediction model by analyzing 456 car accidents having occurred in the 11 tunnels in Busan, through statistical analysis techniques. The results of this study can be summarized as below. As a result of analyzing the characteristics of car accidents, it was found that 64.9% of all the car accidents took place in the tunnels between 08:00 and 18:00, which was higher than 45.8 to 46.1% of the car accidents in common roads. As a result of analyzing the types of car accidents, the car-to-car accident type was the majority, and the sole-car accident type in the tunnels was relatively high, compared to that in common roads. Besides, people at the age between 21 and 40 were most involved in car accidents, and in the vehicle type of the first party to car accidents, trucks showed a high proportion, and in the cloud cover, rainy days or cloudy days showed a high proportion unlike clear days. As a result of analyzing the principal components of car accident influence factors, it was found that the first principal components were road, tunnel structure and traffic flow-related factors, the second principal components lighting facility and road structure-related factors, the third principal factors stand-by and lighting facility-related factors, the fourth principal components human and time series-related factors, the fifth principal components human-related factors, the sixth principal components vehicle and traffic flow-related factors, and the seventh principal components meteorological factors. As a result of classifying car accident spots, there were 5 optimized groups classified, and as a result of analyzing each group based on Quantification Theory Type I, it was found that the first group showed low explanation power for the prediction model, while the fourth group showed a middle explanation power and the second, third and fifth groups showed high explanation power for the prediction model. Out of all the items(principal components) over 0.2(a weak correlation) in the partial correlation coefficient absolute value of the prediction model, this study analyzed variables including road environment variables. As a result, main examination items were summarized as proper traffic flow processing, cross-section composition(the width of a road), tunnel structure(the length of a tunnel), the lineal of a road, ventilation facilities and lighting facilities.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.305-312
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• 2014

Purpose : The purpose of this study is to analyze the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC) and determine the appropriate period of quality assurance (QA). Materials and Methods : The quality assurance of the DMLC equipped with Millennium 120 leaves has been performed total 92 times from January 2012 to June 2014. The the accuracy of leaf position and isocenter coincidence for MLC were checked using the graph paper and Gafchromic EBT film, respectively. The stability of leaf speed was verified using a test file requiring the leaves to reach maximum leaf speed during the gantry rotation. At the end of every leaf speed QA, dynamic dynalog files created by MLC controller were analyzed using dynalog file viewer software. This file concludes the information about the planned versus actual position for all leaves and provides error RMS (root-mean square) for individual leaf deviations and error histogram for all leaf deviations. In this study, the data obtained from the leaf speed QA were used to screen the performance degradation of leaf speed and determine the need for motor replacement. Results : The leaf position accuracy and isocenteric coincidence of MLC was observed within a tolerance range recommanded from TG-142 reports. Total number of motor replacement were 56 motors over whole QA period. For all motors replaced from QA, gradually increased patterns of error RMS values were much more than suddenly increased patterns of error RMS values. Average error RMS values of gradually and suddenly increased patterns were 0.298 cm and 0.273 cm, respectively. However, The average error RMS values were within 0.35 cm recommended by the vendor, motors were replaced according to the criteria of no counts with misplacement > 1 cm. On average, motor replacement for gradually increased patterns of error RMS values 22 days. 28 motors were replaced regardless of the leaf speed QA. Conclusion : This study performed the periodic MLC QA for analyzing the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC). The leaf position accuracy and isocenteric coincidence showed whthin of MLC evaluation is observed within the tolerance value recommanded by TG-142 report. Based on the result obtained from leaf speed QA, we have concluded that QA protocol of leaf speed for DMLC was performed at least bimonthly in order to screen the performance of leaf speed. The periodic QA protocol can help to ensure for delivering accurate IMRT treatment to patients maintaining the performance of leaf speed.