• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.133-144
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• 2004

A model and a measure which can evaluate the risk of rear end collision are developed. Most traffic accidents involve multiple causes such as the human factor, the vehicle factor, and the highway element at any given time. Thus, these factors should be considered in analyzing the risk of an accident and in developing safety models. Although most risky situations and accidents on the roads result from the poor response of a driver to various stimuli, many researchers have modeled the risk or accident by analyzing only the stimuli without considering the response of a driver. Hence, the reliabilities of those models turned out to be low. Thus in developing the model behaviors of a driver, such as reaction time and deceleration rate, are considered. In the past, most studies tried to analyze the relationships between a risk and an accident directly but they, due to the difficulty of finding out the directional relationships between these factors, developed a model by considering these factors, developed a model by considering indirect factors such as volume, speed, etc. However, if the relationships between risk and accidents are looked into in detail, it can be seen that they are linked by the behaviors of a driver, and depending on drivers the risk as it is on the road-vehicle system may be ignored or call drivers' attention. Therefore, an accident depends on how a driver handles risk, so that the more related risk to and accident occurrence is not the risk itself but the risk responded by a driver. Thus, in this study, the behaviors of a driver are considered in the model and to reflect these behaviors three concepts related to accidents are introduced. And safe stopping distance and accident occurrence probability were used for better understanding and for more reliable modeling of the risk. The index which can represent the risk is also developed based on measures used in evaluating noise level, and for the risk comparison between various situations, the equivalent risk level, considering the intensity and duration time, is developed by means of the weighted average. Validation is performed with field surveys on the expressway of Seoul, and the test vehicle was made to collect the traffic flow data, such as deceleration rate, speed and spacing. Based on this data, the risk by section, lane and traffic flow conditions are evaluated and compared with the accident data and traffic conditions. The evaluated risk level corresponds closely to the patterns of actual traffic conditions and counts of accident. The model and the method developed in this study can be applied to various fields, such as safety test of traffic flow, establishment of operation & management strategy for reliable traffic flow, and the safety test for the control algorithm in the advanced safety vehicles and many others.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.111-119
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• 2013

Eleven mycotoxins, including aflatoxins, ochratoxin A, fumonisins, zearalenone, T-2 toxin, deoxynivalenol, and HT-2 toxin, were analyzed simultaneously in rice, barley, and maize produced in 2011 by liquid chromatography coupled with triple quadrupole mass spectrometry (LC/MS/MS). Limits of detection (LOD) are 0.2 ${\mu}g/kg$ for aflatoxin $B_1$, and $G_1$, 0.3 ${\mu}g/kg$ for aflatoxins $B_2$, and $G_2$, 0.1 ${\mu}g/kg$ for ochratoxin, fumonisins, zearalenone, and T-2 toxin and 3.0 ${\mu}g/kg$ for deoxynivalenol and HT-2 toxin. Limits of quantification (LOQ) were 0.6 ${\mu}g/kg$ for aflatoxins $B_1$, and $G_1$, 0.9 ${\mu}g/kg$ for aflatoxins $B_2$, and $G_2$, 0.3 ${\mu}g/kg$ for ochratoxin, fumonisins, zearalenone, and T-2 toxin and 10.0 ${\mu}g/kg$ for deoxynivalenol and HT-2 toxin. Recoveries for 11 mycotoxins ranged from 70.45 to 111.11%. Fumonisins, deoxynivalenol, and zaeralenone were detected from 0.9 to 334.0 ${\mu}g/kg$ in the polished rice, barley and raw corn cultivated in Korea. Other mycotoxins were not detected. Deoxynivalenol contamination was mainly found in barley (24 out of 43 samples) and the average value in positive samples was 113.30 ${\mu}g/kg$.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.61-71
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• 2022

Data from an investigation of vulnerable conifer species in the subalpine zone in Korea obtained by the Korea Forest Service in 2017-2018 and monitoring research conducted by the National Institute of Forest Science since 2014 were used to analyze the status of distribution and growing condition of three major conifer species (Abies nephrolepis, Abies koreana, and Picea jezoensis) in the subalpine zone in the Baekdudaegan protected area. The distribution area of the studied species in the Baekdudaegan protected area was ca. 74% (8,035 ha) of the total distribution area in Korea, indicating that Baekdudaegan is a core area for conservation and restoration of subalpine conifer species. From decline index [A. nephrolepis in Mt. Taebaeksan and Mt. Deogyusan increased by 77.3% and 29.6%, respectively; A. koreana in Mt. Jirisan (Chunwangbong Peak) increased by 45.2% in four years; and P. jezoensis in Mt. Jirisan (Chunwangbong Peak) increased by 47.8% in two years] and seedling frequency (lower frequency of newly recruited seedlings than dead seedlings) results, the studied species are expected to face difficulties in sustainability. In contrast, at Mt. Seseoksan and Chunwangbong Peak in Mt. Jirisan, the health of trees and seedling frequency showed a partial tendency to recover and increase. In addition, we identified the relationship between the decline index and seedling frequency. These results will support the implementation of conservation strategies for vulnerable conifer species in the subalpine zone.

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.160-168
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• 2003

Purpose : To analyze the anterior stability and functional results after the arthroscopic ACL reconstruction and meniscectomy based on meniscus status at the time of surgery. Materials and Methods : From October 1997 to October 2002, 78 patients (male 64 female 14) were treated by arthroscopic ACL reconstruction and meniscectomy and followed more than 12 months (range, $12\~72$ months, average: 32 months). Average age was 32 years old (range, $18\~57$ years old). We divided the patients into 4 groups; Both menisci was intact (BMI, control group), lateral meniscus removed (LMR), medial meniscus removed (MMR) and both menisci removed (BMR). Anterior passive displacement (objective stability) was estimated using KT-2000 arthrometer under the loading of 15lb,20lb and 30lb and evaluated anterior drawer test, Lachman test, range of motion, thigh circumference. Functional evaluation system of IKDC, OAK and Lysholm knee score was used. Results : Average anterior displacement under the loading of 30lb were 2.47 mm, 2.96 mm, 2.96 mm and 3.57 mm in each group(BMI, LMR, MMR, BMR) and it was statistically significant difference (p<0.05). There is no statistically significant difference in average anterior displacement under the loading of 15lb and 20lb in each group but it has showed decreasing tendency in meniscal removed groups. The mean anterior displacement was within 3 mm in 21 cases, 15 cases, 24 cases and 12 cases (total 72 cases, $94\%$) under the loading of 15lb and 20 cases, 15 cases, 24 cases and 11 cases (total 70 cases, $91\%$) under the loading 20lb of in each group and postoperative knee joint stability has showed increasing tendency (p>0.05). The mean score was 94.5, 93.2, 92.2 and 90.4 points in each group and 71 cases $(91\%)$ were more than excellent or good with a OAK score and fair results were noted 4 cases in both meniscal removed group. There were 65 cases $(83\%)$ with a Lysholm knee score more than excellent or good, and IKDC grading were more than normal or nearly normal in 74 cases $(95\%)$ except 4 cases (2 cases in MMR group and 2 cases in BMR group). Conclusion : Long-term anterior stability and functional results of a successful ACL reconstruction affected by tile status of the menisci at the time of surgery and KT-2000 arthrometer was good for estimation of objective follow up.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.146-153
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• 1997

Background : Chronic cough is commomly defined as a persistent or recurrent cough exceeding 3 week's duration. The prevalence of chroinc cough is reported to range from 14% to 23 % for nonsmoking adults. The post nasal drip syndrome has been determined to be the most common cause of chronic cough, followed by asthma, chronic bronchitis, gastroesophageal reflux and bronchiectasis. Cough can be the only manifestation of asthma. Bronchial provocation tests are useful in diagnosing cough variant asthma. We investigated the clinical or laboratory findings and the incidence of airway hyperresponsiveness and evaluated the etiology in patients with chronic cough. Method : We evaluated 46 patients with chronic cough. Methacholine challenge test were done. Results : The results were as follows : 1) Thirty - five percent(16/46) of the chronic cough patients and 44% of the post nasal drip syndrom(7/16) showed the positive responses to methacholine challenge test 2) The underlying causes of chronic cough were post nasal drip syndrome in 35%, bronchitis in 21.7%, cough-variant asthma in 17.4%, and unknown condition in 25.9%. 3) Airway hyperresponsiveness in chronic cough was not related to respiratory symptom, nasal symptom, post nasal drip, smoking, derangement of ventilatory function, atopy, or sinusitis. Conclusion : Airway hyperresponsivenss in patients with chronic cough increased in frequency when compaired with normal control, allergic rhinitis. Cough-variant asthma account for 17.4% of patients with chronic cough.

• Journal of dental hygiene science
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• v.13 no.2
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• pp.165-173
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• 2013

The purpose of this study was to evaluate the surface change after 15% carbamide peroxide home bleaching to various restorative materials (composite resin [CR], resin modified glass ionomer [RMGI] and glass ionomer [GI]) and to observe the effect of surface condition of the materials on re-staining. Three esthetic restorative materials (Filtek Z250, 3M, USA; Fuji II LC, GC, Japan; Fuji II, GC, Japan) were used in this study. Twenty specimens per material group were made and divided into two groups (bleached and control). The specimens were immersed in coffee after applying bleaching agent. The color change and surface roughness were measured before and after bleaching and after immersion in coffee. The data were analyzed with SPSS 18.0. The results were as follows: 1. The color of all experiment groups was significantly changed after bleaching (p<0.05). RMGI was the greatest value of ${\Delta}E^*$ and ${\Delta}L^*$. GI and CR groups were in ordering (p<0.05). The ${\Delta}a^*$ value was decreased GI, RMGI and CR. RMGI was only significantly decreased in ${\Delta}b^*$ value (p<0.05). 2. The surface roughness before and after bleaching was significantly different on CR, RMGI and GI (p<0.05). 3. After staining with coffee, the value of ${\Delta}E^*$ was increased in GI, RMGI and CR, furthermore GI and RMGI showed significant difference in the bleaching groups (p<0.05). The ${\Delta}L^*$ value of GI and RMGI was significantly decreased. 4. The change of surface roughness after staining was not significantly different in all groups (p>0.05). The maintenance of color stability in esthetic restorations is one of the most important properties. Tooth whitening is for the aesthetic. Therefore, dental professionals should notice to patients about re-staining after tooth whitening. They should give an instruction that how to prevent and which kinds of agents could be stained.

• Journal of Korean Dental Hygiene Science
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• v.2 no.2
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• pp.31-39
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• 2019

Background: The purpose of this study was to investigate the effect of self-perception of halitosis on oral health behaviors of college students according to whether they worked in a non-service or service-related job. Methods: A self-reporting questionnaire of 150 university students working in service jobs and 150 university students working in non-service jobs in the metropolitan area was conducted from 26th April to 5th May 2018. The survey tool consisted of 3 general topic areas. There were 5 questions on oral health awareness behavior, 3 questions related to their self-perception of halitosis, and 8 questions on their oral health care practice. All were measured on the Likert 5-point scale. The frequency of their oral health behaviors and their self-perception of halitosis were analyzed according to the subjects' occupation. Pearson's correlation analysis and a linear regression analysis were conducted to confirm the influence of the two. The significance level for the statistical significance test was set to α = 0.05 (two-tailed). Results: In both the service and non-service groups, a coated tongue and food debris were found to influence halitosis(x²=10.95, p=0.027). According to the t-test, taking into account the self-perception of halitosis and oral health behaviors, both were higher in those that had a service job. Self-perception of halitosis and oral health behaviors were found to have a negative correlation(γ=-0.11, p<0.05). As the self-perception of halitosis increased, oral health care practices also increased(Beta=-0.185, p=0.020). Conclusions: Systematic interventions such as oral health programs and health promotion are needed to improve the oral health of service workers.

• Tuberculosis and Respiratory Diseases
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• v.60 no.5
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• pp.532-539
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• 2006

Background : The incidence of pulmonary tuberculosis has been reducing, but endobronchial tuberculosis continues to be a signigicant heath problem. We performed prospectively bronchoscopy in patients diagnosed with pulmonary tuberculosis in order to evaluate the frequency of endobronchial tuberculosis and its related findings. Follow-up bronchoscopy was also performed after treatment to evaluate the incidence of endobronchial complications such as stenosis and remaining lesions. Methods : From January, 1999 to December, 2003, bronchoscopy was performed on patients newly diagnosed with pulmonary tuberculosis. Results : 458 patients were enrolled in this study, out of 699 patients with pulmonary tuberculosis from 1999 to 2003. 234(51%) had endobronchial tuberculosis. The frequency was 40.3% in males and 66.3% in females, The most common symptom was nonspecific cough and sputum, and the main radiologiy finding was patchy infiltration. The most common subtype of endobronchial tuberculosis was the edema-hyperemic form. The right lung was involved more frequently than the left, and the left upper lobe was the most commonly involved site. 58 patients underwent follow-up bronchoscopy and most of been cured without major sequels. However, 8 patients had a stenosis of trachea and main bronchus, and 6 patients had still had endobronchial lesions. Therefore the treatment was prolonged for 3 months. Conclusion : Endobronchial tuberculosis of pulmonary tuberculosis has been remained of high incidence. bronchoscopic and follow-up bronchoscopy examination needs to evaluate the incidence of endobronchial tuberculosis and its related findings and major complication despite of treatment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.1
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• pp.39-47
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• 2009

The importance of securing water resources and their efficient management has attracted more attention recently due to water deficit. In water budget analysis, however, evapotranspiration(${\lambda}E$) has been approximated as the residual in the water balance equation or estimated from empirical equations and assumptions. To minimize the uncertainties in these estimates, it is necessary to directly measure ${\lambda}E$. In this study, using the eddy covariance technique, we have measured ${\lambda}E$ in a mixed forest in the Seolmacheon catchment in Korea from September 2007 to December 2008. During the growing season(May-July), ${\lambda}E$ in this mixed forest averaged about $2.2\;mm\;d^{-1}$, whereas it was on average $0.5\;mm\;d^{-1}$ during the non-growing season in winter. The annual total ${\lambda}E$ in 2008 was $581\;mm\;y^{-1}$, which is about 1/3 of the annual precipitation of 1997 mm. Despite the differences in the amount and frequency of precipitation, the accumulated ${\lambda}E$ during the overlapping period(i.e., September to December) for 2007 and 2008 was both ${\sim}110$ mm, showing virtually no difference. The omega factor, which is a measure of decoupling between forest and the atmosphere, was on average 0.5, indicating that the contributions of equilibrium ${\lambda}E$ and imposed ${\lambda}E$ to the total ${\lambda}E$ were about the same. The results suggest that ${\lambda}E$ in this mixed forest was controlled by various factors such as net radiation, vapor pressure deficit, and canopy conductance. In this study, based on the direct measurements of ${\lambda}E$, we have quantified the relative contribution of ${\lambda}E$ in the water balance of a mixed forest in the Seolmacheon catchment. In combination with runoff data, the information on ${\lambda}E$ would greatly enhance the reliability of water budget analysis in this catchment.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.246-254
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• 2017

Microcystin-LR (MC-LR) is one of most abundant microcystins, and is derived from blue-green algae bloom. Advanced oxidation processes (AOPs) are effective process when high concentrations of MC-LR are released into a drinking water treatment system from surface water. In particular, UV-based AOPs such as UV, $UV/H_2O_2$, $UV/O_3$ and $UV/TiO_2$ have been studied for the removal of MC-LR. In this study, UV-LED was applied for the degradation of MC-LR because UV lamps have demonstrated some weaknesses, such as frequent replacements; that generate mercury waste and high heat loss. Degradation efficiencies of the MC-LR (initial conc. = $100{\mu}g/L$) were 30% and 95.9% using LED-L (280 nm, $0.024mW/cm^2$) and LED-H (280 nm, $2.18mW/cm^2$), respectively. Aromatic compounds of natural organic matter changed to aliphatic compounds under the LED-H irradiation by LC-OCD analysis. For application to raw water, the Nak-dong River was sampled during summer when blue-green algae were heavy bloom in 2016. The concentration of extracellular and total MC-LR, geosmin and 2-MIB slightly decreased by increasing the LED-L irradiation; however, the removal of MC-LR by UV-LED (${\lambda}=280nm$) was insufficient. Thus, advanced UV-LED technology or the addition of oxidants with UV-LED is required to obtain better degradation efficiency of MC-LR.