• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.5
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• pp.71-78
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• 2011

In this paper, we describe the design and implementation of a high efficiency and broad-band Class-J mode power amplifier using gallium nitride(GaN) high-electron mobility transistor(HEMT). The matching circuit of proposed class-J mode power amplifier for 2nd harmonic impedance designed to provide pure reactance alone. The measurement results show that output power of $40{\pm}1$ dBm, power-added efficiency of 50%, and drain efficiency of 60% for a continuous wave signal at 1.4 to 2.6 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.395-398
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• 2016

In this paper, a hybrid MIMO antenna for the mobile communication metal phone with auxiliary letter slot is designed and implemented. Auxiliary letter slot locates on the rear metal cover of the phone, and operates on LTE class 40 band. The slots of two letters are designed and operated with monopole+IFA hybrid antenna. Antenna satisfies under VSWR 3: 1 for LTE class 13 / LTE class 14 / CDMA / GSM / DCS / PCS / W-CDMA / LTE class 40 bands. Average gains and antenna efficiencies measured by the anechoic chamber were -5.57~-1.45 dBi and 27.75~71.6 %, respectively.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.4
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• pp.404-414
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• 2014

Yield prediction is important to manage semiconductor quality. Many researches with machine learning algorithms such as SVM (support vector machine) are conducted to predict yield precisely. However, yield prediction using SVM is hard because extremely imbalanced and big data are generated by final test procedure in semiconductor manufacturing process. Using SVM algorithm with imbalanced data sometimes cause unnecessary support vectors from major class because of unselected support vectors from minor class. So, decision boundary at target class can be overwhelmed by effect of observations in major class. For this reason, we propose a under-sampling method with minor class based SVM (MCSVM) which overcomes the limitations of ordinary SVM algorithm. MCSVM constructs the model that fixes some of data from minor class as support vectors, and they can be good samples representing the nature of target class. Several experimental studies with using the data sets from UCI and real manufacturing process represent that our proposed method performs better than existing sampling methods.

• Journal of The Korean Association For Science Education
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• v.30 no.4
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• pp.519-531
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• 2010

In this study, we investigated the elementary school students' images of science class and the factors influencing their formations. 280 sixth graders were selected from nine elementary schools in Gyeonggi province and Gangwon province and the DASCT-C (Draw-A-Science-Class-Test Checklist) was administered. In addition, four students were individually interviewed in order to investigate their responses deeply. Analyses of the results revealed that the students' images of science class for four science subjects (physics, chemistry, biology, and earth science) were more 'student-centered' than 'teacher-centered' or 'neutral'. The students of the teacher with student-centered image of science class had also more student-centered images than those with teacher-centered images. Many students answered that the main factors affecting their images of science class were the experiences of impressed or funny science classes, the perceptions of wanted science classes, the active science learning experiences, the educational experiences outside the school curriculum, and the negative science learning experiences. Educational implications of these findings are discussed.

• Journal of the Korea Convergence Society
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• v.6 no.4
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• pp.169-176
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• 2015

The purpose of this study was to analyze the relationship between sports confidence and class satisfaction according to adolescents' participation in marine sports. First, as a result of analyzing the correlation between sports confidence and class satisfaction, confidence on specific sports had a positive (+) effect on class contents, class style, and class effect, and had a negative (-) effect on physical education teachers. Competition orientation had a positive (+) effect on class contents, class style, and class effect. State sports confidence had a positive (+) effect on all the sub-factors of class satisfaction. Second, as a result of analyzing the effect of sports confidence on class satisfaction, class contents and class style had positive (+) effects on competition orientation and state sports confidence, and class environment and physical education teachers had positive (+) effects on state sports confidence and negative (-) effects on competition orientation.

• Journal of Korean Elementary Science Education
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• v.29 no.4
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• pp.427-440
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• 2010

The purpose of this study is to develop a science writing teaching strategy, and to apply it to the fourth-graders in elementary science classes. We examined its effect on their motivation, attitude, and understanding of science concept. For the research fourth grade children were grouped into three classes: an experimental class A of 27 children, an experimental class B of 24 and a comparative class of 27. All of them are from H elementary school in Seoul, Korea. Experimental class A learned science writing with a newly developed strategy while experimental class B learned science writing in a traditional method. Comparative class did not learn science writing. As a result, class A showed positive changes on students' science motivation, attitude, and understanding of science concept. In addition, class B with even one science writing task for a chapter had higher achievement in the understanding of science concept than the comparative class had.

• Journal of Chest Surgery
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• v.28 no.2
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• pp.143-149
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• 1995

From January, 1983, to August, 1993, 23 cases of pericardiectomy for chronic constrictive pericarditis were carried out. The 15 male and 8 female patients ranged in age from 7 to 68 years[mean 39.1 years . All patients underwent pericardiectomy through a median sternotomy. Postoperative complications were low cardiac output[2 patients , wound infection[2 patients , pneumonia[2 patients , and unilateral phrenic nerve palsy[2 patients . One patient died of low cardiac output 1 day after pericardiectomy due to the associated transposition of great artery and hypoplastic right lung. Clinical and pathological findings showed that the cause of constrictive pericarditis was tuberculous in 8 cases[34.8% , idiopathic in 12 cases[52.2% and pyogenic in 3 cases[13.0% . Central venous pressure fell below 10cmH2O by immediate in 6 cases, fell below 10cmH2O by 24hrs in 5 cases and continued above 10cmH2O after 24hrs in 12 cases. Preoperative NYHA functional class of patients showed class I-1, classII-4, class III-14, and class IV-3. Postoperativly NYHA functional class was improved to class I-15, classII-6, class III-1.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.69-79
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• 1986

The purpose of this investigation was to know correlation of mean values between centric occlusion and centric relation by the cephalogram in Angle's Class Ⅰ and Ⅲ malocclusion subjects. 22 adults with Angle's Class Ⅰ malocclusion (17 men and 5 women, 21 to 27 years of age) and 14 adults with Angle's Class Ⅲ malocclusion (10 men and 4 women, 21 to 27 years of age) were selected from the dental students in Yonsei University. Each subject was given two lateral cephalometric radiographies and cephalometric analysis was performed. All data from these analyses was recorded and statistically processed with CYBER computer system. 1. The results were obtained as follows: There was a strong positive correlation between centric occlusion and centric relation in all subjects with Angle's Class Ⅰ and Ⅲ malocclusion. 2. In Angle's Class Ⅰ malocclusion, measurements in lower facial height revealed significant difference between centric occlusion and centric relation (P<0.05). In Angle's Class Ⅲmalocclusion, measurements in facial axis angle, mandibular plane angle, convexity of A point, lower incisor protrusion, lower facial height revealed significant difference between centric occlusion and centric relation (P<0.05). 3. When the mandible was moved from centric occlusion to centric relation, the mean distance of mandibular movement was 1.27㎜ (0.2-2.8㎜) in Angle's Class Ⅰ malocclusion, 1.70㎜ (0.55-4.15㎜) in Angle's Class Ⅲ malocclusion, and 1.44㎜ (0.2-4.15㎜) in all subjects.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.4
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• pp.611-620
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• 2010

The purpose of this study was to analysis of the image of elementary school teachers on special class. The Q-methodology was used as a research method which is useful for analyzing subjectivity like as human value, attitude, belief and image. P-sample as subjects of this study was collected from 40 elementary school teacher in Busan. A data was analyzed using QUANL PC program. As a result of research, the image of elementary school teachers on special class was classified as 4 type. The 1 type was labeled the practical proponent type. The 1 type teachers highly estimate the educational importance of the special class and thought it as a place that educational possibility of children with disabilities can come true. The 2 type was labeled the passive bystander type. They are quite indifferent to the special class, and are skeptical about the educational achievement of children with disabilities. The 3 type was labeled the ideational positive type. They admit the importance of the special class, but thought that the image about the special class highly depends on the ability of the teachers who take responsibility for it. The 4 type was labeled the realistic opponent. They criticize the special class for not being the place that inclusion education for children with disabilities comes true and they are dissatisfied with the fact that ordered-curriculum for children with disabilities isn't applied at all.

• The korean journal of orthodontics
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• v.46 no.3
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• pp.137-145
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• 2016

Objective: The purpose of this study was to investigate the characteristics of orthodontic patients at Yonsei Dental Hospital from 2008 to 2012. Methods: We evaluated Angle's classification from molar relationships, classification of skeletal malocclusion from the A point-nasion-B point angle, facial asymmetry, and temporomandibular joint disorders (TMDs) from the records of 7,476 patients who received an orthodontic diagnosis. The orthognathic surgery rate, extraction rate, and extraction sites were determined from the records of 4,861 treated patients. Results: The patient number increased until 2010 and gradually decreased thereafter. Most patients were aged 19-39 years, with a gradual increase in patients aged ${\geq}40years$. Angle's Class I, Class II divisions 1 and 2, and Class III malocclusions were observed in 27.7%, 25.6%, 10.6%, and 36.1% patients, respectively, with a gradual decrease in the frequency of Class I malocclusion. The proportion of patients with skeletal Class I, Class II, and Class III malocclusions was 34.3%, 34.3%, and 31.4%, respectively, while the prevalence of facial asymmetry and TMDs was 11.0% and 24.9%, respectively. The orthognathic surgery rate was 18.5%, with 70% surgical patients exhibiting skeletal Class III malocclusion. The overall extraction rate among nonsurgical patients was 35.4%, and the maxillary and mandibular first premolars were the most commonly extracted teeth. Conclusions: The most noticeable changes over time included a decrease in the patient number after 2010, an increase in the average patient age, and a decrease in the frequency of Angle's Class I malocclusion. Our results suggest that periodic characterization is necessary to meet the changing demands of orthodontic patients.