• 한국수학교육학회지시리즈A:수학교육
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• 제56권1호
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• pp.63-80
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• 2017

By analysing the examination papers from third grade high school students, we classified the errors occurred in the problem solving process of high school 'Geometry and Vectors' into several types. There are five main types - (A)Insufficient Content Knowledge, (B)Wrong Method, (C)Logical Invalidity, (D)Unskilled Expression and (E)Interference.. Type A and B lead to an incorrect answer, and type C and D cannot be distinguished by multiple-choice or closed answer questions. Some of these types are classified into subtypes - (B1)Incompletion, (B2)Omitted Condition, (B3)Incorrect Calculation, (C1)Non-reasoning, (C2)Insufficient Reasoning, (C3)Illogical Process, (D1)Arbitrary Symbol, (D2)Using a Character Without Explanation, (D3) Visual Dependence, (D4)Symbol Incorrectly Used, (D5)Ambiguous Expression. Based on the these types of errors, answers of each problem was analysed in detail, and proper ways to correct or prevent these errors were suggested case by case. When problems that were used in the periodical test were given again in descriptive forms, 67% of the students tried to answer, and 14% described flawlessly, despite that the percentage of correct answers were higher than 40% when given in multiple-choice form. 34% of the students who tried to answer have failed to have logical validity. 37% of the students who tried to answer didn't have enough skill to express. In lessons on curves of secondary degree, teachers should be aware of several issues. Students are easily confused between 'focus' and 'vertex', and between 'components of a vector' and 'coordinates of a point'. Students often use an undefined expression when mentioning a parallel translation. When using a character, students have to make sure to define it precisely, to prevent the students from making errors and to make them express in correct ways.

• 전기전자학회논문지
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• 제15권3호
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• pp.198-204
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• 2011

본 논문에서는 선택적 증폭후 전달(Opportunistic Amplify-and-Forward: OAF) 릴레이 시스템에 대한 새로운 성능 분석 기법을 레일리 페이딩 채널에 대하여 제안하였다. 제안된 분석 기법에서는 집합 연산(set-operation)을 기반으로 각 릴레이가 최적의 릴레이로 선택될 확률을 유도한다. 그리고 수신된 순시 신호 대 잡음비의 확률 밀도 함수를 기존의 분석 기법보다 일반적인 (확률밀도함수 표현에서 합 기호의 개수 및 그 영역이 구체화된)형태로 제시한다. 그리고 이를 이용하여 평균 오류율, 누락 확률 및 평균 채널 용량을 근사화된 닫혀진 형태로 유도한다. 제안된 성능분석 기법의 정확성은 모의실험을 통하여 검증한다. 성능분석 및 모의실험 결과 비교를 통하여 OAF 기법이 평균 오류 확률, 누락 확률 및 평균 채널 용량 측면에서 비선택적 기법에 비해 성능 향상 정도가 우수함을 확인한다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.226-229
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• 2006

The safety of on-going ships is one of important concerns in the view of environment and human life. The ship in bad condition is likely to be subjected to accidental loads such as collision. Once she has one or several minor collision damages in the form of circle or ellipse, her ultimate strength under compression or tension load will be reduced. Here, it is important to evaluate the reduction ratio of ultimate strength due to the damage from safety point of view. The problem of strength reduction of a plate with cutout such as opening hole has been treated by many researchers. As a result, a closed-form formula on the reduction of ultimate strength of a plate considering the effect of several forms of cutout was suggested. However, the structure of ships is composed of a plate and a stiffener so-called a stiffened plate, and it is likely to be damaged at a plate and stiffeners together in collision. This paper is to investigate the effect of minor collision damage on ultimate strength of a stiffened plate by using numerical analysis. For this study, the shape of minor collision damage of a stiffened plate was made by using contact algorithm. The deformed shape was used as an initial shape for ultimate stress analysis. Then, a series of nonlinear FE analysis was conducted to investigate the reduction effects of ultimate strength of the stiffened plate. The boundary condition was applied as simply supported at all boundaries, and the tripping of stiffener among failure mode under compression loading was neglected. These results were settled in the form of reduction ratio between ultimate of original intact stiffened plate and that of damaged stiffened plate.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.1913-1918
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• 2014

Background: The study is the first of its kind to be conducted in Saudi Arabia (KSA), aiming to analyze the effectiveness of an intervention program in improving the knowledge of oral cancer among the youth. Materials and Methods: A total of 1,051 young Saudis (57% males and 43% females with a mean age of $20.4{\pm}1.98$) were selected using multi-stage cluster sampling. Knowledge assessment was accomplished using a closed-ended questionnaire which was subjected to reliability tests. Prevalence of risk factors in relation to gender was analyzed using the chi-squared test. Effectiveness was calculated by comparing the pre- and post-intervention means, using the two-tailed paired t-test. Multiple logistic regression was employed in order to determine factors associated with awareness of risk habits, signs/symptoms and prevention of oral cancer. The significance level in this study was set at 0.05. Results: Females were seen to be more into the habit of sheesha smoking (3.3% rather than the use of other forms of risk factors. Prevalence of diverse risk factors such as cigarette smoking (20%), sheesha (15.3%), khat (27%) and shamma (9%) was seen among males. Gender and the use of modifiable risk factors among the study sample were significantly (p<0.001) associated with effectiveness of the intervention. The intervention program was highly effective (p<0.001) in improving the knowledge of oral cancer among the youth in Jazan, KSA. Multivariate analysis revealed that age and gender are the most significant factors affecting knowledge. Conclusions: The study gives a direction for further public health initiatives in this oral cancer prone region.

• Asian Pacific Journal of Cancer Prevention
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• 제13권10호
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• pp.5189-5193
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• 2012

Kemerovo is an industrial region of the Russian Federation characterized by highly developed mining, chemical, metallurgical and power industries. Many of the factories were closed down due to the socioeconomical crisis in the early 90's, and economic potential of the survivors has also decreased significantly. Paradoxically, this has led to the improvement of the ecological situation in the region and elimination of exposure to many chemical carcinogens. This factor, in combination with the improvement of oncological care, might be expected to have lead to a decline of cancer incidence and mortality in the region. To assess trends of cancer incidence and mortality in Kemerovo Region, we therefore carried out an analysis of relevant epidemiological data during 1991-2010. In fact, a significant increase of cancer incidence overall was revealed during 2001-2010. Male cancer incidence was significantly higher than female cancer incidence. Regarding gastric cancer incidence, statistically significant differences during 2001-2010 were found only for men, and male incidence exceeded female incidence. Concerning colorectal cancer incidence, it was lower during 2001-2005 and 2006-2010 as compared to the period of 1991-1996. Lung cancer incidence was significantly higher during 1991-2000 compared to 2001-2010. Among urban populations, cancer incidence was higher in comparison with rural population, but a gradual steady convergence of trends of cancer incidence among urban and rural populations was noted. Lung cancer, breast cancer, colorectal cancer, non-melanoma skin cancer, and gastric cancer are the most prevalent cancer forms in Kemerovo Region. There were no differences in cancer mortality between 2001-2005 and 2006-2010; however, male cancer mortality exceeded female cancer mortality. A similar situation was observed for gastric cancer, colorectal cancer, and lung cancer. Cancer mortality among urban populations exceeded mortality among rural population, for both genders. We suggest that these data can be used for development of modern programs of cancer prevention and early diagnostics in industrial regions of Siberia.

• Journal of Chest Surgery
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• 제22권2호
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• pp.308-314
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• 1989

Pulmonary sequestration is a congenital malformation characterized by an area of embryonic lung tissue that derives its blood supply from an anomalous systemic artery. Two forms recognized: extralobar and intralobar. Extralobar form is a very rare congenital malformation, usually located in the lower chest, and may be found in newborn infants at the time a congenital diaphragmatic hernia is repaired. Large sequestrated segments may be cause acute respiratory distress in the neonate. The condition is asymptomatic in 15 per cent of patients. This report presents two cases of pulmonary sequestration which misdiagnosed a superior mediastinal tumor and a benign lung tumor. First case was 30-year-old male patient and chief complaints were dyspnea, dry cough and right chest pain. Chest X-ray showed a homogenous increased density of smooth margin at the right superior mediastinal area and suggested a benign mediastinal tumor. And so explothoracotomy was made without other special studies. Second case was 28-year-old male patient. One month ago, he had tracheostomy and right closed thoracostomy due to massive hemoptysis and spontaneous hemothorax. Chest X-ray showed a benign cystic lesion at RLL area. At the time of operation, in first case, a mass of adult fist size was placed medial to the right upper lobe and densely adhesive to trachea, SVC and esophagus. Blood supply of the mass was bronchial arteries of trachea and RUL bronchus and drained to SVC and azygos vein through anomalous systemic veins. There was no bronchial communication on Frozen biopsy. In 2nd case, large cystic lesion contained old blood hematoma was located in RLL and anomalous blood vessel from thoracic aorta was drained to posterior segment of RLL. In operation field, intralobar pulmonary sequestration was diagnosed, and RLL lobectomy was carried out.

• 의료법학
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• 제15권2호
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• pp.285-316
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• 2014

As the number of medical disputes regarding nurses has increased after medical disputes have increase, there is a need for a study on it. However, the legal relationship between nurses and patients has not yet been analyzed. Recently, the role and function of nurses are expanded according to the development of the science of nursing; moreover their activity and limitation of responsibility are also expanded. For this reason, the medical disputes regarding nurses have been increasing. However, the majority of these kind of dispute are just passed over because their practice is usually considered to be a mere action to assist doctor's role. In addition, nurse practice is not a secondary action of doctor's role, but forms part of a medical treatment. Of course, nurses handle many secondary tasks after doctors finish their medical treatment. But this is only part of the whole tasks of nurses. Furthermore, the general details of their medical treatment are not different from those of doctors because they also belong to the medical service personnel. Considering these features of nurse and the medical condition in South Korea, their task is becoming increasingly developed and specialized and they are also establishing their own field. With this stream of times, there is a growing interest in enacting a Nursing Practice Act, in other words, the independent law on nurse for the sake of patient safety and national health promotion. Then, their responsibility will distinctly be expanded as much more. That is, the time that nurses practice their medical care by following doctors' order and also pass over their responsibility to doctors is closed. Thus, this study examines the features and responsibilities of nursing practice, and discusses an institutional framework to efficiently cope with the legal disputes between nurses and patients. It aims to throw light on the decision making on nurse-patient disputes in future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5301-5323
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• 2017

Small cell deployment offers a low-cost solution for the boosted traffic demand in heterogeneous cellular networks (HCNs). Besides improved spatial spectrum efficiency and energy efficiency, future HCNs are also featured with the trend of network architecture convergence and feasibility for flexible mobile applications. To achieve these goals, dual connectivity (DC) is playing a more and more important role to support control/user-plane splitting, which enables maintaining fixed control channel connections for reliability. In this paper, we develop a tractable framework for the downlink SINR analysis of DC assisted HCN. Based on stochastic geometry model, the data-control joint coverage probabilities under multi-frequency and single-frequency tiering are derived, which involve quick integrals and admit simple closed-forms in special cases. Monte Carlo simulations confirm the accuracy of the expressions. It is observed that the increase in mobility robustness of DC is at the price of control channel SINR degradation. This degradation severely worsens the joint coverage performance under single-frequency tiering, proving multi-frequency tiering a more feasible networking scheme to utilize the advantage of DC effectively. Moreover, the joint coverage probability can be maximized by adjusting the density ratio of small cell and macro cell eNBs under multi-frequency tiering, though changing cell association bias has little impact on the level of the maximal coverage performance.

• Imaging Science in Dentistry
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• 제50권3호
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• pp.193-198
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• 2020

Purpose: This study investigated knowledge, attitudes, and perceptions regarding the future of artificial intelligence (AI) for radiological diagnosis among dental specialists in central India. Materials and Methods: An online survey was conducted consisting of 15 closed-ended questions using Google Forms and circulated among dental professionals in central India. The survey consisted of questions regarding participants' recognition of and attitudes toward AI, their opinions on directions of AI development, and their perceptions regarding the future of AI in oral radiology. Results: Of the 250 participating dentists, 68% were already familiar with the concept of AI, 69% agreed that they expect to use AI for making dental diagnoses, 51% agreed that the major function of AI would be the interpretation of complicated radiographic scans, and 63% agreed that AI would have a future in India. Conclusion: This study concluded that dental specialists were well aware of the concept of AI, that AI programs could be used as an adjunctive tool by dentists to increasing their diagnostic precision when interpreting radiographs, and that AI has a promising role in radiological diagnosis.

• Nuclear Engineering and Technology
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• 제30권5호
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• pp.403-415
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• 1998

The CANDU 6 reactor assembly consists of an array of 380 pressure tubes, which are installed horizontally in a large cylindrical vessel, the Calandria, containing the low pressure heavy water moderator. The pressure tube is located inside the calandria tube and the annulus between these tubes, which forms a closed loop with $CO_2$ gas recirculating, is called the Annulus Gas System(AGS). It is designed to give an alarm to the operator even for a small pressure tube leak by a very sensitive dew point meter so that he can take a preventive action for the pressure tube rupture incident. To judge whether the operator action time is enough or not in the design of Wolsong 2,3 & 4, the Leak Before Break(LBB) assessment is required for the analysis of the pressure tube failure accident. In order to provide the required data for the LBB assessment of Wolsong Units 2, 3, 4, a series of leak detection capability tests was performed by injecting controlled rates of heavy water vapour. The data of increased dew point and rates of rise were measured to determine the alarm set point for the dew point rate of rise of Wolsong Unit 2. It was found that the response of the dew point depends on the moisture injection rate, $CO_2$ gas flow rate and the leak location. The test showed that CANDU 6 AGS can detect the very small leaks less than few g/hr and dew point rate of rise alarm can be the most reliable alarm signal to warn the operator. Considering the present results, the first response time of dew point to the AGS $CO_2$ flow rate is approximated.