• Sleep Medicine and Psychophysiology
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• v.21 no.2
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• pp.61-68
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• 2014

Objective: The aim of the present study is to assess the prevalence and related risk factors of suicide ideation among middle and high school students in an urban area. Methods: We surveyed 3,691 middle and high school students (2,159 male, 1,532 female, 11-19 years of age) using a self-report questionnaire that covered basic socio-demographic data, academic achievements, presence of physical or psychiatric illness, sleep duration on weekdays, time spent at private academies on weekdays and weekends, and subjective needs for counseling. The Beck Depression Inventory (BDI) and Reynolds' Suicidal Ideation Questionnaire (SIQ) were included in the survey. Results: The prevalence of students with high suicide ideation ($SIQ{\geq}62$) was 4.6%. In a logistic regression model, female sex (p = 0.002), younger age (p < 0.001), poor academic achievement (p = 0.043) and higher score of BDI (p < 0.001) were associated with a higher SIQ score. In addition, younger age (p = 0.045) and a higher BDI score (p < 0.001) were associated with a higher SIQ score adolescents having high suicide ideation ($SIQ{\geq}62$). Conclusion: Related risk factors of suicide ideation in adolescents were female sex, younger age, poor academic achievement, and a depressive mood. It would be especially helpful to pay more attention to younger adolescents and a depressive mood as a high-risk group. The understanding of these factors will be helpful for providing an effective suicide screening and prevention program for adolescents.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.131-137
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• 2017

This study investigated the risk factor of Gallbladder stone in Busan and Kyungnam area. The subjects of the experiment was performed with patients by abdominal ultrasonography among the patients who came to the P hospital from June 2016 to December 2016. Among them, risk factors were analyzed on 353 people at the same time when abdominal ultrasonography and hematological test. The statistical analysis of risk factors related to the Gallbladder stone was performed by independent t-test and chi-square test. In consider of difference verification result for calculations odds ratio about independent variables, multiple logistic regression analysis to conduct verify adequacy by calculating forecasting model from variable. As a result, Gallbladder stone risk factors have relevance to age ${\gamma}GTP$ with probability model and values to calculated. Age was showed sensitivity 49.7%, specificity 82.2%, receiver operating characteristic area under curve 0.724. Forecasting probability sensitivity 69.3%, specificity 62.4%, receiver operating characteristic area under curve 0.699 showed, ${\gamma}GTP$ confirmed validity of forecasting model.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.15-26
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• 2006

Although numerous investigations have been performed over the years to predict the behavior and bearing capacity of piles, the mechanisms are not yet entirely understood. The prediction of bearing capacity is a difficult task, because large numbers of factors affect the capacity and also have complex relationship one another. Therefore, it is extremely difficult to search the essential factors among many factors, which are related with ground condition, pile type, driving condition and others, and then appropriately consider complicated relationship among the searched factors. The present paper describes the application of Artificial Neural Network (ANN) in predicting the capacity including its components at the tip and along the shaft from dynamic load test of the driven piles. Firstly, the effect of each factor on the value of bearing capacity is investigated on the basis of sensitivity analysis using ANN modeling. Secondly, the authors use the design methodology composed of ANN and genetic algorithm (GA) to find optimal neural network model to predict the bearing capacity. The authors allow this methodology to find the appropriate combination of input parameters, the number of hidden units and the transfer structure among the input, the hidden and the out layers. The results of this study indicate that the neural network model serves as a reliable and simple predictive tool for the bearing capacity of driven piles.

• Economic and Environmental Geology
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• v.56 no.3
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• pp.331-341
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• 2023

When creating a soil contamination map using geostatistical techniques, there are various sources that can affect prediction errors. In this study, a grid-based soil contamination map was created from the sampling data of heavy metal concentrations in soil in abandoned mine areas using Ordinary Kriging. Five factors that were judged to affect the prediction error of the soil contamination map were selected, and the variation of the root mean squared error (RMSE) between the predicted value and the actual value was analyzed based on the Leave-one-out technique. Then, using a machine learning algorithm, derived the top three factors affecting the RMSE. As a result, it was analyzed that Variogram Model, Minimum Neighbors, and Anisotropy factors have the largest impact on RMSE in the Standard interpolation. For the variogram models, the Spherical model showed the lowest RMSE, while the Minimum Neighbors had the lowest value at 3 and then increased as the value increased. In the case of Anisotropy, it was found to be more appropriate not to consider anisotropy. In this study, through the combined use of geostatistics and machine learning, it was possible to create a highly reliable soil contamination map at the local scale, and to identify which factors have a significant impact when interpolating a small amount of soil heavy metal data.

• Journal of Hospice and Palliative Care
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• v.1 no.1
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• pp.30-38
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• 1998

Background : Hepatocellular carcinomoma is the 3rd most common malignancy and the 2nd most common cause of death in Korea. The prediction of life-expectancy in terminal cancer patients is a major problem for patients, families, and physicians. We would like to investigate the prognostic factors of hepatocellular carcinoma, and therefore contribute to the prediction of the survival time of patients with hepatocellular carcinoma. Methods : A total of 91 patients(male 73, female 18) with hepatocellular carcinoma who were admitted to the hospital between January and lune 1995 were entered into the study, and data were collected prospectively on 28 clinical parameters through medical obligation record. We surveyed an obligation and local district office records, and confirmed the surivival of patients till July, 1996. Using Cox-proportional hazard model, give the significant variables related to survival. These determined prognostic factors. Life regressional analysis was used, there were calculated predicted survival day based on combinations of the significant prognostic factors. Results : 1) Out of 91 patients, 73 were male, and 18 were female. The mean age was $56.7{\pm}10.6$ ears. During the study, except for 16 patients who could not follow up, out of 75 patients, the number of deaths was 57(76%) and the number of survivals was 18(24%). 2) Out of the 28 clinical parameters, the prognostic factors related to reduced survival rate were prothrombin time<40%(relative risk:10.8), weight loss(RR:4.4), past history of hypertension (RR:3.2), ascites(RR:2.8), hypocalcemia(RR:2.5)(P<0.001). 3) Out of five factors, the survival day is 1.7 in all of five, $4.2{\sim}10.0$ in four, $10.4{\sim}41.9$ in three, $29.5{\sim}118.1$ in two, $124.0{\sim}296.6$ in one, 724.0 in none. Conclusion : In hepatocellular carcinoma we found that the prognostic factors related to reduce survival rate were prolonged prothrombin time(<40%), weight loss, past history of hypertension, ascites, and hypocalcemia(<8.7mg/dl). The five prognostic factors enabled the prediction of life-expectancy in patients with hepatocellular carcinoma and may assist in managing patients with hepatocellular carcinomal.

• Korean Journal of Head & Neck Oncology
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• v.30 no.1
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• pp.1-4
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• 2014

배경 및 목적 타액선 선양낭성암종은 느린 성장 속도와 늦은 원격 전이를 특징으로 하는 드문 상피성종양이다. 본 연구는 다양한 임상 병리학적 변수를 통해 선양낭성암종의 원격 전이에 영향을 주는 인자를 조사하고자 하였다. 대상 및 방법 1999년 10월부터 2011년 12월까지 본원 이비인후과에서 타액선 선양낭성암종으로 진단되어 치료 받은 44명(남자 19명, 여자 25명)을 대상으로 원격전이를 유발하는 위험 인자를 조사하였다. 8명의 환자는 배제 기준에 따라 제외하였다. 환자의 평균 연령은 54세였다. 환자의 병리 보고서, 종양의 크기, T 병기, 수술 절제연의 종양 존재 유무, 신경 조직 침습, 림프절 전이가 조사되었다. 결 과 15명의 환자가 원격전이가 있었으며 21명은 원격 전이가 없었다. 원격 전이를 유발할 수 있는 여러 인자들을 비교하였을 때, 원격 전이는 수술 절제연의 종양 세포 잔존(p=0.014), 종양의 크기(p=0.038), 진행된 T 병기(p=0.024)가 통계적으로 유의하게 연관성이 있었다. 림프절 전이와 신경 조직 침습은 원격 전이와 연관이 없었다. 결 론 종양의 크기, 진행된 T 병기, 수술 후 절제연의 종양 세포 잔존은 원격 전이의 예측 인자로 생각된다. 따라서 이에 해당하는 환자의 경우 더욱 철저한 관리 및 경과 관찰을 요한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.23 no.2
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• pp.54-60
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• 1981

토양유실은 강우의 성질, 토양의 특성, 경사도 및 경사장, 배수방법에 따라 달라진다. 따라서 토양유실을 정확하게 예측하기 위해서는 위의 6개 인자에 관한 구명이 필요하다. 지금까지 우리 나라에서는 Wischmeier의 토양유실량 공식(USLE)을 효율적으로 적용하기 위하여 6개 인자중 강우인자, 토양침식관성 인자, 작물인자 및 토양보존인자에 대해서만 연구가 있는 실정이다. 따라서 본 연구에서는 경사지에서의 경사장가 경사도가 토양유실에 미치는 영향을 구명하여 LS방정식을 유도하고자 하였다. 경기도 나주군 숙거리에 있는 농업진흥공사 농지 보존 시험소에서 10개의 과지 시험구에 대한 토양유실량을 측정하여 분석하였다. 10개의 시험구중 9개는 경사도 10%, 20% 및 30% 각각에 대해 10m, 20m 및 30m의 경사장으로 되어있으며 나머지 1개의 시험구는 다른 시험구와의 비교를 위한 표준구로서 15%의 경사도, 20m의 경사장으로 되어 있다. 토양은 예산류에 속하며 60%의 초질, 24%의 미초질 및 16%의 정토질로 구성되어 있다. 20회의 토양유실량 측정 기록중 12.7mm 이상의 강우에 의한 9회분의 유실량 측정자료를 회귀분석한 결과 다음과 같은 방정식이 유도되었다. 그러나 경사도와 경사장인자(LS)는 다른 여러 인자들과의 상호작용(interaction)을 내포하고 있기 때문에 앞으로의 LS 인자에 대한 연구는 여러 종류의 토양에서 경사의 조건을 다양하게 변화시켜 장기간 실험을 한다면 한국의 토양특성에 일반적으로 적용할 수 있는 LS방정식을 유도할 수 있으리라 사료된다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.3-14
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• 2000

미래를 예측하는 것은 어떤 의미에선 힘들지 않다. 그것은 미래를 예측하는 데는 상상할 수 없을 정도로 우리가 고려해야 할 인자가 많아 완전한 예측은 불가능함으로 별로 주저하지 않고 불확실한 사실도 예언하고 책임을 지지 않는데 우리는 익숙해 있기 때문이다. 과거에 누구도 오늘의 인류문명을 내다보지 못했으며 더구나 앞으로 일어날 변화를 확신을 갖고 예측하는 것은 점점 더 힘들어지고 있다. 로마클럽의 보고서 "성장의 한계"도 출판 당시는 세계를 떠들석하게 했지만, 지금에 와서는 과거의 기념비적 사건으로 묻혀버리고 만 것을 보아도 알 수 있다.(중략) 수 있다.(중략)

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.205-209
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• 1996

원자로 입구노즐에서 원자로 냉각재 펌프에 의한 맥동압력 준위를 원자로 하향통로와 저온 관을 상관시켜 예측하는 방법에 관하여 분석하였다. 원자로 하향통로에서의 맥동압력은 원자로 내부구조물의 건전성 평가에 쓰이는 중요한 인자로 이 값을 정확히 구하기 위해서는 경계조건인 입구노즐에서의 맥동압력을 정확히 예측해야 한다. 이를 위해 원자로 하향통로와 저온관을 상관시켜 원자로 입구노즐에서의 펌프에 의한 맥동압력 준위를 계산하였으며 Palo Verde Unit 1의 실험치와 비교 분석하였다. 분석 결과, 제시된 맥동압력 준위 예측모델은 500℉의 경우 비교적 잘 일치하였으나, 565℉의 경우 상당한 차이가 있었으므로 추가적인 검토 및 수정 작업이 요구된다.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.731-745
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• 2021

In this study, the monthly temperature of the Han River basin was predicted by statistical multiple regression models that use global climate indices and weather data of the target region as predictors. The optimal predictors were selected through teleconnection analysis between the monthly temperature and the preceding patterns of each climate index, and forecast models capable of predicting up to 12 months in advance were constructed by combining the selected predictors and cross-validating the past period. Fore each target month, 1000 optimized models were derived and forecast ranges were presented. As a result of analyzing the predictability of monthly temperature from January 1992 to December 2020, PBIAS was -1.4 to -0.7%, RSR was 0.15 to 0.16, NSE was 0.98, and r was 0.99, indicating a high goodness-of-fit. The probability of each monthly observation being included in the forecast range was about 64.4% on average, and by month, the predictability was relatively high in September, December, February, and January, and low in April, August, and March. The predicted range and median were in good agreement with the observations, except for some periods when temperature was dramatically lower or higher than in normal years. The quantitative temperature forecast information derived from this study will be useful not only for forecasting changes in temperature in the future period (1 to 12 months in advance), but also in predicting changes in the hydro-ecological environment, including evapotranspiration highly correlated with temperature.