• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.2
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• pp.109-120
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• 2017

A discounted cost model for preventive maintenance of armor units of rubble-mound breakwaters is mathematically derived by combining the deterioration model based on a discrete-time stochastic process of shock occurrence with the cost model of renewal process together. The discounted cost model of condition-based maintenance proposed in this paper can take into account the nonlinearity of cumulative damage process as well as the discounting effect of cost. By comparing the present results with the previous other results, the verification is carried out satisfactorily. In addition, it is known from the sensitivity analysis on variables related to the model that the more often preventive maintenance should be implemented, the more crucial the level of importance of system is. However, the tendency is shown in reverse as the interest rate is increased. Meanwhile, the present model has been applied to the armor units of rubble-mound breakwaters. The parameters of damage intensity function have been estimated through the time-dependent prediction of the expected cumulative damage level obtained from the sample path method. In particular, it is confirmed that the shock occurrences can be considered to be a discrete-time stochastic process by investigating the effects of uncertainty of the shock occurrences on the expected cumulative damage level with homogeneous Poisson process and doubly stochastic Poisson process that are the continuous-time stochastic processes. It can be also seen that the stochastic process of cumulative damage would depend directly on the design conditions, thus the preventive maintenance would be varied due to those. Finally, the optimal periods and scale for the preventive maintenance of armor units of rubble-mound breakwaters can be quantitatively determined with the failure limits, the levels of importance of structure, and the interest rates.

• Journal of Korea Water Resources Association
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• v.57 no.7
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• pp.437-449
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• 2024

Rainfall-runoff prediction studies using deep learning while considering catchment attributes have been gaining attention. In this study, we selected two models: the Transformer model, which is suitable for large-scale data training through the self-attention mechanism, and the LSTM-based multi-state-vector sequence-to-sequence (LSTM-MSV-S2S) model with an encoder-decoder structure. These models were constructed to incorporate catchment attributes and predict the inflow of 10 multi-purpose dam watersheds in South Korea. The experimental design consisted of three training methods: Single-basin Training (ST), Pretraining (PT), and Pretraining-Finetuning (PT-FT). The input data for the models included 10 selected watershed attributes along with meteorological data. The inflow prediction performance was compared based on the training methods. The results showed that the Transformer model outperformed the LSTM-MSV-S2S model when using the PT and PT-FT methods, with the PT-FT method yielding the highest performance. The LSTM-MSV-S2S model showed better performance than the Transformer when using the ST method; however, it showed lower performance when using the PT and PT-FT methods. Additionally, the embedding layer activation vectors and raw catchment attributes were used to cluster watersheds and analyze whether the models learned the similarities between them. The Transformer model demonstrated improved performance among watersheds with similar activation vectors, proving that utilizing information from other pre-trained watersheds enhances the prediction performance. This study compared the suitable models and training methods for each multi-purpose dam and highlighted the necessity of constructing deep learning models using PT and PT-FT methods for domestic watersheds. Furthermore, the results confirmed that the Transformer model outperforms the LSTM-MSV-S2S model when applying PT and PT-FT methods.

• Clinical and Experimental Pediatrics
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• v.51 no.2
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• pp.188-203
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• 2008

Purpose : Asthma is one of the most common chronic childhood disease. Education of asthmatic children and their families about asthma and its management may improve disease control, reduce symptoms, and improve school performance. The aim of the study was to evaluate the effects of an intensive asthma education program in asthmatic children and their families on outcome measure of asthma management behavior scale, knowledge about asthma, self efficacy scale and quality of life. Methods : Fifteen asthmatic children and their families were invited the intensive asthma education program which including allergen avoidance, management of asthma, correct use of the inhalation devices and control of exercise-induced asthma (study group). Fifteen asthmatic children and their families those who did not participate this program were served as control group. Participants were asked to complete a written questionnaire before and 3-month after the program. Results : After completing the intensive education program, significant improvement of the childrens asthma management behavior scale (27.1 vs. 32.2, P=0.011), belief and knowledge about asthma (14.2 vs. 17.9, P<0.001), self efficacy (47.9 vs. 49.7, P=0.091) and quality of life (79.6 vs. 88.6, P<0.001) was noted in the study group by measuring questionnaires. There are increasing tendencies in parental asthma management behavior scale and knowledge about asthma. Conclusion : This intensive asthma education program is effective in improving asthma control, self efficacy and quality of life of asthmatic children. This should serve as a national model for family-based programs for asthmatic children and their families.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.433-446
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• 2005

The purpose of this study was to investigate the sociopsychological factors which might influence the course of the temporomandibular disorders and to develop models for prediction of treatment outcome related to pain, dysfunction and sound. For this study, 268 patients with temporomandibular disorders were selected from the patients presented to department of Oral Medicine, Wonkwang university dental hospital. Chief complaints of these subjects were largely grouped into three categories such as pain, dysfunction and sound, and 10 cm visual analogue scale(VAS) was used to record the state of the three complaints every visit and Treatment Index(VAS TI) was calculated from VAS. All the forty-two items obtained from clinical examination or questionnaire were statistically processed with $SPSS^{(R)}$ windows. The results of this study were as follows: 1. The items showed a difference between male and female subjects were maximum mouth opening, palpation score, jaw jerk during mandibular movement, and sleep disturbance. Among questionnaires such as SRRS, HAD scale and PSQI, the HAD scales showed the most highly significant correlation with the each scale item of the SCL-90R. 2. Among the groups classified by VAS TI, the group with the lowest VAS TI showed the highest VAS score in the start of treatment but showed the lowest score in the end of treatment, without respect to the type of chief complaint. From these results, it is assumed that the active treatment duration for the subjects with lower VAS score in the first visit would be longer than the subjects with higher score with the somewhat poor treatment outcome. 3. With regard to all the three complaints, the items showing significant effect in the model for prediction of treatment outcome were from questionnaire, except one item, maximum mouth opening, which suggest that the sociopsychological factors would be strongly related to development and progress of the symptoms.

• Tuberculosis and Respiratory Diseases
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• v.65 no.3
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• pp.191-197
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• 2008

Background: Due to the irreversible nature of chronic obstructive pulmonary disease (COPD), the treatment aim in patients with COPD is not to cure but to reduce the symptoms, increase lung function, and improve the quality of life. It has been suggested that depression is a common emotional disturbance in patients with COPD who are faced with a major physical impairment and embarrassing symptoms. This study evaluated the prevalence and risk factors of depression in patients with chronic obstructive pulmonary disease. Methods: A total of 59 patients with a registered diagnosis of chronic obstructive pulmonary disease were selected. Depression was assessed using the Centers for Epidemiologic Studies Depression (CES-D) scale. The quality of life was assessed using the Korean version of the St. George's Respiratory Questionnaire. Results: The prevalence of depression was 17.0%. In the correlation model, the interaction of the $FEV_1%$ over predicted value and SGRQ score(symptom, activity, impact, overall score) was statistically significant. The interaction of the $FEV_1%$ over predicted value and depression scale(CES-D) was also statistically significant. There was a positive correlation between the SGRQ scores(symptom, activity, impact, overall score) and the depression scale. Conclusion: The prevalence of depression in patients with chronic obstructive pulmonary disease is relatively high. The pulmonary function and the living standards were found to be significant risk factors for depression.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.390-397
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• 2013

The study, utilizing a data envelopment analysis (DEA) which is one of the nonparametric estimation methods, aims to evaluate the management efficiency of chestnut tree cultivators in such provinces in Chungchungnam-do as Cheong-yang, Gong-ju, Bu-yeo and so on. The analysis data of this study is based on inputs and outputs of 20 forestry households surveyed in the 2012 survey titled 'A Study on Current Level and Condition of Chestnut Cultivation and Management', which was conducted from March 2012 to October 2012. The elements of inputs are composed of management cost, harvesting cost, material cost, non-operation expenses and cultivation area, while the element of output is a gross margin only. Then the study analyzes a technical efficiency, a puretechnical efficiency and a scale efficiency using CCR and BCC model among DEA methods. Based on that, it also provides improvement methods for forestry households that turned out to be inefficient. In order to verify the result of DEA analysis, the study additionally compares a result of this efficiency study with that of chestnuts management standard diagnostic table. According to the result, the average value of technical efficiency analyzed was 0.667, proving to be inefficient in general. Given that the average value of pure-technical efficiency was 0.944 and that of scale efficiency was 0.703, it can be inferred that inefficiency exists in the field of scale, not in the field of cultivation techniques. As for forestry households with the efficiency score of 1, it is shown that there were 6 households that recorded 1 in the technical efficiency field and 13 households that recorded 1 in the pure technical efficiency. Meanwhile, there were 6 households that recorded 1 in all of the three aspects. In the comparison with the scores from chestnuts management standard diagnostic table, there were 5 households made a high score of over 80, among which are 3 households with score 1 in the technical efficiency. Also, the results of this study and the chestnuts management standard diagnostic table are proved to have the same result, both of them showing the same households that recorded the highest score and the lowest score. This means the management efficiency evaluation using DEA can be applied to the fieldwork along with the chestnuts management standard diagnostic table.

• Korean Journal of Psychosomatic Medicine
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• v.27 no.2
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• pp.101-110
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• 2019

Objectives : It is not clear which clinical variables are most closely associated with delirium in the Intensive Care Unit (ICU). By comparing clinical data of ICU delirium and non-delirium patients, we sought to identify variables that most effectively differentiate delirium from non-delirium. Methods : Medical records of 6,386 ICU patients were reviewed. Random Subset Feature Selection and Principal Component Analysis were utilized to select a set of clinical variables with the highest discriminatory capacity. Statistical analyses were employed to determine the separation capacity of two models-one using just the selected few clinical variables and the other using all clinical variables associated with delirium. Results : There was a significant difference between delirium and non-delirium individuals across 32 clinical variables. Richmond Agitation Sedation Scale (RASS), urinary catheterization, vascular catheterization, Hamilton Anxiety Rating Scale (HAM-A), Blood urea nitrogen, and Acute Physiology and Chronic Health Examination II most effectively differentiated delirium from non-delirium. Multivariable logistic regression analysis showed that, with the exception of vascular catheterization, these clinical variables were independent risk factors associated with delirium. Separation capacity of the logistic regression model using just 6 clinical variables was measured with Receiver Operating Characteristic curve, with Area Under the Curve (AUC) of 0.818. Same analyses were performed using all 32 clinical variables;the AUC was 0.881, denoting a very high separation capacity. Conclusions : The six aforementioned variables most effectively separate delirium from non-delirium. This highlights the importance of close monitoring of patients who received invasive medical procedures and were rated with very low RASS and HAM-A scores.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.65-78
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• 2006

This paper investigates the cost structure ot the Korea and Japan railroad industry with respect to density, scale and scope economies as well as productivity growth rate using a generalized trans)og multiproduct cost function model. The paper then assumes that the Korea and Japan railway companies pi·educe three outputs (incumbent railway passenger-kilometers. Shinkansen passenger-kilometers, ton-kilometers of freight) using four input factors (labor, fuel, maintenance, rolling stock and capital). The specified cost function includes foul other independent variables: track lengths to reflect network effects, two dummies to reflect nation and ownership effects, and time trend as a proxy for technical change. The simultaneous equation system consisting of a cost function and three input share equations is estimated with the Zellner's iterative seemingly unrelated regression. The unbalanced panel data used in the paper, a total of 154 observations. are collected from the annual records of the Korea National Railroad (KNR) for the yews $1977{\sim}2003$, Japan National Railways (JNR) for the years $1977{\sim}1984$. seven Japan Railways (JR's) for the years $1987{\sim}2003$. The findings show that the Korean and Japanese railways exhibit product-specific and overall economies of density but product-specific diseconomies of scale with respect to incumbent railway passenger-kilometers, Shinkansen-kilometers and ton-kilometers. However, the railways experience mild overall economies of scale which result from economies of scope associated with the joint production of incumbent railway/Shinkansen and feight, freight/incumbent railway and Shinkansen except Shinkansen/incumbent railway and freight. In addition, the economies of density and scale in the KNR, JR east, JR central, and JR west companies at the point of the years $1990{\sim}2003$ average is generally analogous to the above results at the point of sample average. There also appear to be economies of ssope associated with the joint Production of the incumbent railway and Shinkansen in JR central but diseconomies of scope in JR East and JR West. The findings also indicate that the productivity growth rate of the privately-owned JR's is larger than that of the government-owned KNR.

• Journal of Gifted/Talented Education
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• v.23 no.1
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• pp.109-128
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• 2013

The purpose of this study is to verify the validity of KEDI Leadership Inventory (Simplified) for elementary and secondary school student. The existing Leadership Inventory is outdated by excessive or insufficient items. To verify reliability and validity of this KEDI Leadership Inventory (Simplified), we analyze internal consistency of scale for reliability and construct validity, convergent and discriminative validity. criterion-related validity. The internal consistency of the scale is relatively high from .610 to .838 for elementary school student, and from .734 to .936 for secondary school student To verify construct validity, we analyze a confirmatory factor analysis using AMOS whether revealed that the structural equation model including 5 construct validity in KEDI Leadership Inventory(Simplified) showed fit index at a satisfactory level as follows. The major fit indexes are showed as follows; CFI (.954), TLI (.943), RMSEA (.068) in the scale for elementary school student, CFI (.935), TLI (.915), RMSEA (.070) in the scale for secondary school student. Futhermore, to secure criterion-related validity, this KEDI Leadership Inventory(Simplified) showed significant correlations with student's leader position in their classroom for r=.358 (p<.01), and gifted education students are significantly higher .50 than no gifted student. This KEDI Leadership Inventory (Sim'plified) is made up of parsimonious 20 items, so that teachers can be convenient to identify intra-inter personal leadership characteristics of a student and recommend the student for gifted education institution.

• Korean Journal of School Psychology
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• v.17 no.3
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• pp.401-419
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• 2020

The purpose of this study was to validate the Korean Implementation Fidelity Checklist of Tier 1 School-Wide Positive Behavior Support (KIFC-T1) for use in the Korean educational system. Tier 1 support, which is universal supports, within a multi-tiered, school-wide positive behavior support (SWPBS) model, aims to provide support to and prevent problem behaviors among all students in a school. The initial KIFC-T1 consisted of 48 items and 11 factors and was developed based on a literature review. Its content was validated by experts. The validated KIFC-T1 was introduced to 185 special school teachers who had experience implementing SWPBS and who used the instrument to assess the degree to which their schools had implemented Tier 1 support. Based on their responses, the construct validity of the KIFC-T1 was examined using factor, item, and internal consistency reliability analyses. The concurrent validity of the tool was examined using the PBS Evaluation Tool, School Climate Questionnaire, School Discipline Practice Scale, and PBS Effectiveness Scale. The analyses revealed that KIFC-T1 had a stable five-factor structure with 35 items, had good reliability (Cronbach's α=.956, each factor's Cronbach's α=.834-.951), and its results were statistically significantly correlated with those of the PBS Evaluation Tool, School Discipline Practice Scale, and the PBS Effectiveness Scale. However the KIFC-T1's results were not statistically significantly correlated with the results of the School Climate Questionnaire. These results suggest that KIFC-T1 is a reliable and valid tool for assessing the fidelity of universal support implementations.