• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.85-95
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• 1996

Obstructive sleep apnea syndrome(OSAS) in childhood is unique and different n-om that in adulthood in several aspects, including pathophysiology, clinical features, diagnostic criteria, complications, management, and prognosis. Characteristic features of childhood OSAS in comparison with the adult form are the variety of severe complications such as developmental delay, more prominent behavioral and cognitive impairments, vivid cardiovascular symptoms, and increased death risk, warranting a special attention to the possible diagnosis of OSAS in children who snore. However, the childhood OSAS is often neglected and unrecognized. We, therefore, report a case of very severe OSAS in a 5-year-old boy who was sucessfully treated with continuous positive airway pressure(CPAP) treatment. Interestingly, the patient was comor-bid with the attention deficit hyperactivity disorder. Prior to the initial visit to us, adenotonsillectomy had been done at the age of 4 with no significant improvement of apneic symptoms and heavy snoring. On the initial diagnostic procedures, marked degree of snoring was audible even in the daytime wake state and the patient was observed to be very hyperactive. Increased pulmonary vascularity with borderline cardiomegaly was noted on chest X-ray. The baseline polysomnography revealed that the patient was very sleep-apneic and snored very heavily, with the respiratory disturbance index(RDI) of 46.9 per hour of sleep, the mean SaO2 of 78.8%, and the lowest SaO2 of 40.0%(the lowest detectable oxygen level by the applied oxymeter). The second night polysomnography was done for CPAP titration and the optimal pressure turned out to be $8.0\;cmH_2O$. The applied CPAP treatment was well tolerated by the patient and was found to be very effective in alleviating heavy snoring and severe repetitive sleep apneas. After 18 months of the CPAP treatment, the patient was followed up with nocturnal polysomnography(baseline and CPAP nights) and clinical examination. Sleep apneas were still present without CPAP on the baseline night. However, the severity of OSAS was significantly decreased(RDI of 15.7, mean SaO2 of 96.2%, and the lowest SaO2 of 83.0%), compared to the initial polysomnographic findings before initiation of long-term CPAP treatment. Wechsler intelligence tests done before and after the CPAP treatment were compared with each other and surprising improvement of intelligence(total 9 points, performance 16 points) was noted. Clinically he was found to be markedly improved in his attention deficit hyperactive behavior after CPAP treatment, but with minimal change of TOVA(test of variables of attention) scores except conversion of reaction time score into normal range. On the chest X-ray taken after 18 months of CPAP application, the initial cardiopulmonary abnormalities were not found at all. We found that the CPAP treatment in a young child is very effective, safe, and well-tolerated and also improves the co-morbid attention deficit hyperactive symptoms. Overall, the growth and development of the child has been facilitated with the long-term use of CPAP. Cardiovascular complications induced by OSAS have been also normalized with CPAP treatment. We suggest that early diagnosis and active treatment intervention of OSAS in children are crucial in preventing and ameliorating possible serious complications caused by repetitive sleep apneas and consequent hypoxic damage during sleep.

• Management & Information Systems Review
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• v.30 no.4
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• pp.147-173
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• 2011

It is generally accepted that there are momentum effects in the short term and reversal effects in the long term, which makes abnormal excess returns in the major stock markets in the world. In Korea stock market, however, the previous studies demonstrate that contrarian strategies based on reversal effects are more effective than momentum strategies following momentum effects in the short term as well as in the long term. This paper examines wether contrarian strategies are still effective In Korea stock market from 1980 to 2009, and the short term reversals may be changed after the foreign exchange crisis in 1997-1998. Moreover, this paper investigates how contrarian profits are shown considering the state of market. In my research, unlike previous studies, I find that both of contrarian strategies using price change and price level cannot gain excess risk adjusted returns in Korea stock market from 1980 to 2009, but this result is due to the fact that reversal effects existed before the foreign exchange crisis but momentum effects does after the foreign exchange crisis in 1997-1998. Specially, after the foreign exchange crisis, it is confirmed momentum strategies using 52 week high price, that is, price level are more effective than momentum strategies using price change. And following the strategies using 52 week high price after the foreign exchange crisis, the momentum is not only observed in the up market but also in the down market, which is different with the results of the studies regarding to American market, where the momentum is just found in the up market.

• The Korean Society of Law and Medicine
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• v.19 no.2
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• pp.41-72
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• 2018

In the division of labor (or teamwork) in medicine, the responsibility of medical and nursing staff should be separated or distributed to justify negligent criminal offenses. The present work refers to the standards by which the due diligence and responsibility of the individual persons are to be determined and delimited. In this context, it has been proven that objective theory as a measure of due diligence is appropriate. From a moral point of view, when assessing due diligence, it makes sense to impose greater individual or higher performance demands on the perpetrator, but law and order require that due diligence should result from socially relevant human behavior. To give objective measure of negligence and to provide the highest level of personal responsibility, so that man can not be burdened too much responsibility and it is accordingly with an equality theorem. Afterwards some points are presented, which should be considered in a concrete fact in the determination of the medical negligence. Medical action has specific characteristics such as professionalism, discretionary and exclusive, unbalance of information. These characteristics distinguish medical actions from general negligence. The general level of knowledge, the urgency, working condition and working environment of the medical facility, duration of the professional practice, assessment of the medical activity are crucial in this context. As a standard of delineation of due diligence, I have used the permitted risk and the principle of trust. In the horizontal division of labor, the principle of trust applies. The principle of trust applies in principle in cases of division of labor interaction, when doctors in the same hospital exercise their own specific occupational field or everyone works in another hospital. However, this is not true for every case. In the vertical division of labor, the principle of trust does not apply and the senior physician can not trust the assistant doctors. In this case, the principle of trust is converted into a duty of supervision for assistant doctors by the senior physician. This supervision requirement could be used as a random check.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.637-651
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• 2019

In the event of a major accident such as an explosion in a refinery or a petrochemical plant, it has caused a serious loss of life and property and has had a great impact on the insurance market. In the case of catastrophic incidents occurring in process industries such as refinery and petrochemical plants, only the proximate causes of loss have been drawn and studied from inspectors or claims adjustors responsible for claims of property insurers, incident cause investigators, and national forensic service workers. However, it has not been done well for conducting root cause analysis (RCA) and identifying the factors that contributed to the failure and establishing preventive measures before leading to chemical plant's catastrophic incidents. In this study, the criteria of warning signs on CCPS catastrophic incident waning sign self-assessment tool which was derived through the RCA method and the contribution factor analysis method using the swiss cheese model principle has been reviewed first. Secondly, in order to determine the major incident warning signs in an actual chemical plant, 614 recommendations which have been issued during last the 17 years by loss control engineers of global reinsurers were analyzed. Finally, in order to facilitate the assessment index for catastrophic incident warning signs, the criteria for the catastrophic incident warning sign index at chemical plants were grouped by type and classified into upper category and lower category. Then, a catastrophic incident warning sign index for a chemical plant was developed using the weighted values of each category derived by applying the analytic hierarchy process (pairwise comparison method) through a questionnaire answered by relevant experts of the chemical plant. It is expected that the final 'assessment index for catastrophic incident warning signs' can be utilized by the refinery and petrochemical plant's internal as well as external auditors to assess vulnerability levels related to incident warning signs, and identify the elements of incident warning signs that need to be tracked and managed to prevent the occurrence of serious incidents in the future.

• Journal of Intelligence and Information Systems
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• v.25 no.1
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• pp.127-137
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• 2019

Recidivism prediction has been a subject of constant research by experts since the early 1970s. But it has become more important as committed crimes by recidivist steadily increase. Especially, in the 1990s, after the US and Canada adopted the 'Recidivism Risk Assessment Report' as a decisive criterion during trial and parole screening, research on recidivism prediction became more active. And in the same period, empirical studies on 'Recidivism Factors' were started even at Korea. Even though most recidivism prediction studies have so far focused on factors of recidivism or the accuracy of recidivism prediction, it is important to minimize the prediction misclassification cost, because recidivism prediction has an asymmetric error cost structure. In general, the cost of misrecognizing people who do not cause recidivism to cause recidivism is lower than the cost of incorrectly classifying people who would cause recidivism. Because the former increases only the additional monitoring costs, while the latter increases the amount of social, and economic costs. Therefore, in this paper, we propose an XGBoost(eXtream Gradient Boosting; XGB) based recidivism prediction model considering asymmetric error cost. In the first step of the model, XGB, being recognized as high performance ensemble method in the field of data mining, was applied. And the results of XGB were compared with various prediction models such as LOGIT(logistic regression analysis), DT(decision trees), ANN(artificial neural networks), and SVM(support vector machines). In the next step, the threshold is optimized to minimize the total misclassification cost, which is the weighted average of FNE(False Negative Error) and FPE(False Positive Error). To verify the usefulness of the model, the model was applied to a real recidivism prediction dataset. As a result, it was confirmed that the XGB model not only showed better prediction accuracy than other prediction models but also reduced the cost of misclassification most effectively.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.167-175
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• 2019

To effectively deal with the fire in tunnel which is mostly the vehicle fire, it's more important to suppress the fire at early stage. In urban tunnel, however, accessibility to the scene of fire by the fire fighter is very limited due to severe traffic congestion which causes the difficulty with firefighting activity in timely manner and such a problem would be further worsened in underground road (double-deck tunnel) which has been increasingly extended and deepened. In preparation for the disaster in Korea, the range of life safety facilities for installation is defined based on category of the extension and fire protection referring to risk hazard index which is determined depending on tunnel length and conditions, and particularly to directly deal with the tunnel fire, fire extinguisher, indoor hydrant and sprinkler are designated as the mandatory facilities depending on category. But such fire extinguishing installations are found inappropriate functionally and technically and thus the measure to improve the system needs to be taken. Particularly in a double-deck tunnel which accommodates the traffic in both directions within a single tunnel of which section is divided by intermediate slab, the facility or the system which functions more rapidly and effectively is more than important. This study, thus, is intended to supplement the problems with existing tunnel life safety system (fire extinguishing) and develop the remote-controlled automatic fire extinguishing system which is optimized for a double-deck tunnel. Consequently, the system considering low floor height and extended length as well as indoor hydrant for a wide range of use have been developed together with the performance verification and the process for commercialization before applying to the tunnel is underway now.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.658-672
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• 2022

The unique teaching and learning difficulties of speed-related units in elementary school science are mainly due to the student's lack of mathematical thinking ability and procedural knowledge on speed measurement, and curriculums and textbooks must be constructed with these in mind. To identify the implications of composing a new science curriculum and relevant textbooks, this study reviewed the structure and contents of the speed-related units of three curriculums from the 2007 revised curriculum to the 2015 revised curriculum and the resulting textbooks and examined their relevance in light of the literature. Results showed that the current content carries the risk of making students calculate only the speed of an object through a mechanical algorithm by memorization rather than grasp the multifaceted relation between traveled distance, duration time, and speed. Findings also highlighted the need to reorganize the curriculum and textbooks to offer students the opportunity to learn the meaning of speed step-by-step by visualizing materials such as double number lines and dealing with simple numbers that are easy to calculate and understand intuitively. In addition, this paper discussed the urgency of improving inquiry performance such as process skills by observing and measuring an actual object's movement, displaying it as a graph, and interpreting it rather than conducting data interpretation through investigation. Lastly, although the current curriculum and textbooks emphasize the connection with daily life in their application aspects, they also deal with dynamics-related content somewhat differently from kinematics, which is the main learning content of the unit. Hence, it is necessary to reorganize the contents focusing on cases related to speed so that students can grasp the concept of speed and use it in their everyday lives. With regard to the new curriculum and textbooks, this study proposes that students be provided the opportunity to systematically and deeply study core topics rather than exclude content that is difficult to learn and challenging to teach so that students realize the value of science and enjoy learning it.

• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.121-142
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• 2023

As the number and weight of imported food are steadily increasing, safety management of imported food to prevent food safety accidents is becoming more important. The Ministry of Food and Drug Safety conducts on-site inspections of foreign food facilities before customs clearance as well as import inspection at the customs clearance stage. However, a data-based safety management plan for imported food is needed due to time, cost, and limited resources. In this study, we tried to increase the efficiency of the on-site inspection by preparing a machine learning prediction model that pre-selects the companies that are expected to fail before the on-site inspection. Basic information of 303,272 foreign food facilities and processing businesses collected in the Integrated Food Safety Information Network and 1,689 cases of on-site inspection information data collected from 2019 to April 2022 were collected. After preprocessing the data of foreign food facilities, only the data subject to on-site inspection were extracted using the foreign food facility_code. As a result, it consisted of a total of 1,689 data and 103 variables. For 103 variables, variables that were '0' were removed based on the Theil-U index, and after reducing by applying Multiple Correspondence Analysis, 49 characteristic variables were finally derived. We build eight different models and perform hyperparameter tuning through 5-fold cross validation. Then, the performance of the generated models are evaluated. The research purpose of selecting companies subject to on-site inspection is to maximize the recall, which is the probability of judging nonconforming companies as nonconforming. As a result of applying various algorithms of machine learning, the Random Forest model with the highest Recall_macro, AUROC, Average PR, F1-score, and Balanced Accuracy was evaluated as the best model. Finally, we apply Kernal SHAP (SHapley Additive exPlanations) to present the selection reason for nonconforming facilities of individual instances, and discuss applicability to the on-site inspection facility selection system. Based on the results of this study, it is expected that it will contribute to the efficient operation of limited resources such as manpower and budget by establishing an imported food management system through a data-based scientific risk management model.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.1
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• pp.125-140
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• 2023

Careful preparation for a start-up can lower the risk of failure and create a successful business model. However, there are still challenges for middle-aged entrepreneurs, as start-up services and policies are often not readily accessible or fully utilized. Despite active research on middle-aged start-ups, previous studies have not delved deeply into the demographics of start-up preparation and various preparation behaviors. In response to this, a study was conducted to identify which start-up support services middle-aged entrepreneurs use, and how start-up preparation can be classified based on this. Data from 324 middle-aged tech start-up owners, based in Seoul and who started their businesses within the past 7 years, was collected and analyzed. The results showed that middle-aged entrepreneurs had moderate start-up preparation, with the greatest focus on the preparation period and the least focus on start-up education. Latent Profile Analysis revealed three groups of start-up preparation types among middle-aged entrepreneurs: "Overall Tribal Type," "Lack of Start-up Education Type," and "Comprehensive Preparation Type." BCH was performed on start-up satisfaction, start-up competence, fear of failure, access to start-up services, and support needs for middle-aged entrepreneurs based on the preparation type. The results showed that "Overall Tribal Type" had statistically lower start-up satisfaction, competence, and service accessibility compared to the other groups. Meanwhile, "Comprehensive Preparation Type" had a statistically lower fear of failure than the other types. "Overall Tribal Type" also had lower accessibility to middle-aged start-up services. All types had a high recognition of the need for support for specialized middle-aged start-ups. The findings highlight the need for more comprehensive support for middle-aged entrepreneurs. This could include expanding support projects to enhance their level of preparation, providing customized support based on their level of preparation, and improving the visibility and accessibility of start-up support services for middle-aged individuals. Additionally, specialized education that addresses the characteristics of middle-aged individuals should be provided.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.2
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• pp.1-20
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• 2023

The purpose of this study is to identify the unique entrepreneurial behavioral attributes of social enterprises that are distinct from for-profit enterprises at the organizational level, derive a social entrepreneurship model that reflects the unique characteristics of social enterprises as strategic decision-making and organizational behavioral tendencies. In order to effectively achieve the purpose of this study, previous studies were reviewed, and qualitative studies were conducted using the grounded theory method based on this. In this study, social entrepreneurship was identified as five sub-factors through a series of analysis processes, and 'Social value orientation; Innovativeness; Pro-activeness; Risk taking; Cooperation orientation' was newly proposed. It also proposed a new social entrepreneurship framework that integrates and explains the multidimensional model of social entrepreneurship by reviewing and connecting the relationships between each sub-factor of the research model. The 'social entrepreneurship framework' classified the social entrepreneurship model into 'pro-social motivation', 'pro-social behavior', and 'entrepreneurial behavior' attributes and explained them by linking them with each sub-factor that constitutes social entrepreneurship. The most remarkable difference between this study and previous studies is that it identified and added 'Cooperation orientation' as a sub-factor constituting social entrepreneurship from the organizational-level behavioral point of view. Through this study, 'Cooperation orientation' was identified as a major behavioral tendency for social enterprises to materialize pro-social motivation, strengthen the economic foundation of business activities, and improve the efficiency of business operations. 'Cooperation orientation' is a major behavioral tendency that strengthens the legitimacy of business activities between pro-social motivation and profit-seeking of social enterprises, improves the performance of social value creation activities, and overcomes the difficulties of resource constraints through cooperation with the outside and improves operational efficiency. In addition, it was confirmed that 'Cooperation orientation' is a major behavioral tendency of social enterprises that is manifested simultaneously in social value-oriented activities and entrepreneurial activities pursuing profit. The 'Cooperation orientation' newly identified in the study supplements the previous research, increases the explanatory power of the theory of social entrepreneurship, and provides the basis for theoretical expansion to subsequent researchers.