• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.84-92
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• 2000

A GaAs MESFET MMIC transmitter for 2.4 GHz wireless local loop handset is designed and fabricated. The transmitter consists of a double balanced active mixer and a two stage driver amplifier with voltage negative feedback. In particular, a pair of CS-CG(common source-common gate) structure compensates the reduction in dynamic range caused by unbalanced complementary IF input signals. And to suppress the leakage local power at RF port, the mixer is designed by using phase characteristic between the ports of MESFET. At the bias condition of 2.7 V and 55.2 mA, the fabricated MMIC transmitter with chip dimensions of $0.75\times1.75 mm^2$ obtains a measured conversion gain of 38.6 dB, output $P_{idB}$ of 11.6 dBm, and IMD3 at -5 dBm RF output power of -31.3 dBc. This transmitter is well suited for WLL handset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.365-373
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• 2015

In this paper, a planar antenna with monopole-like radiation pattern for on-body communications is proposed. The proposed antenna consists of three split-rings(SR) to generate a monopole-like radiation characteristic. To account for the on-body application, the proposed antenna is designed to have a low-profile. The antenna has an overall dimensions of $0.29{\lambda}_0{\times}0.29{\lambda}_0{\times}0.008{\lambda}_0$ at 5.8 GHz industrial, scientific, and medical(ISM) band(5.725~5.875 GHz). To verify the body effect, a two-thirds muscle equivalent semi solid phantom is fabricated and used to measure the antenna performance. The 10-dB return loss bandwidth is 280 MHz(5.68~5.96 GHz) and the measured peak gain is 1.91 dBi.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.331-342
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• 2016

Objective: To evaluate the accuracy and reliability of the diagnostic tools available for assessing maxillary transverse deficiencies. Methods: An electronic search of three databases was performed from their date of establishment to April 2015, with manual searching of reference lists of relevant articles. Articles were considered for inclusion if they reported the accuracy or reliability of a diagnostic method or evaluation technique for maxillary transverse dimensions in mixed or permanent dentitions. Risk of bias was assessed in the included articles, using the Quality Assessment of Diagnostic Accuracy Studies tool-2. Results: Nine articles were selected. The studies were heterogeneous, with moderate to low methodological quality, and all had a high risk of bias. Four suggested that the use of arch width prediction indices with dental cast measurements is unreliable for use in diagnosis. Frontal cephalograms derived from cone-beam computed tomography (CBCT) images were reportedly more reliable for assessing intermaxillary transverse discrepancies than posteroanterior cephalograms. Two studies proposed new three-dimensional transverse analyses with CBCT images that were reportedly reliable, but have not been validated for clinical sensitivity or specificity. No studies reported sensitivity, specificity, positive or negative predictive values or likelihood ratios, or ROC curves of the methods for the diagnosis of transverse deficiencies. Conclusions: Current evidence does not enable solid conclusions to be drawn, owing to a lack of reliable high quality diagnostic studies evaluating maxillary transverse deficiencies. CBCT images are reportedly more reliable for diagnosis, but further validation is required to confirm CBCT's accuracy and diagnostic superiority.

• The korean journal of orthodontics
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• v.44 no.3
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• pp.119-127
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• 2014

Objective: To evaluate the long-term effects of self-ligating brackets (SLBs) on transverse dimensions of arches and skeletal and soft tissues and to quantitatively evaluate the treatment outcome after non-extraction treatment with SLBs. Methods: The sample consisted of 24 (18 female and six male) subjects, with a mean age of $14.23{\pm}2.19$ years, who received treatment with the Damon$^{(R)}$3 appliances. Complete records including cephalometric radiographs and plaster models were obtained before treatment (T1), immediately after treatment (T2), six months after treatment (T3), and two years (T4) after treatment. Digital study models were generated. Twenty lateral cephalometric, six frontal cephalometric, and eight dental cast measurements were examined. The Peer Assessment Rating index was used to measure the treatment outcome. The Wilcoxon test was applied for statistical analysis of the changes. Results: There were significant increases in all transverse dental cast measurements with active treatment. There was some significant relapse in the long term, particularly in maxillary width (p < 0.05). Statistically significant increases were found in nasal (p < 0.001), maxillary base, upper molar, lower intercanine, and antigonial (p < 0.05) widths in T1-T2. Lower incisors were proclined and protruded in T1-T2. Conclusions: SLBs correct crowding by mechanisms involving incisor proclination and protrusion and expansion of the dental arches, without induction of clinically significant changes in hard and soft tissues of the face.

• Imaging Science in Dentistry
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• v.35 no.2
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• pp.97-103
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• 2005

Purpose : To determine if ultrasonography is a reliable technique to assess masseter muscle sites within intra- and interobserver and the scanning level and/or the muscle condition affect local cross-sectional dismension (LCSD) measurements of masseter muscle. Materials and Methods : 10 subjects without sign and symptom of temporomandibular disorders and missing posterior teeth were examined by ultrasonography. Bilateral ultrasonographic examinations were performed with a linear (B-scan) 7.5 MHz small-part transducer to register LCSDS of the masseter muscle on three different levels. Scans were made on relaxed and clenching condition. Three oral and maxillofacial radiologists measured at two sessions with a time interval of at least 5 minutes. Results : Variables such as 'condition' and 'level' had a significant effect on muscle measurements (p<0.05). There was no significant difference between 'sessions'(p>0.05) and 'observers' (p>0.05). LCSDS on lower scan level were significantly thinner than those on upper and middle level. Those on clenching condition were significantly thicker than those on relaxed condition (p<0.05). The scanning level with the highest reproducibility was middle with clenching condition (ICC=0.90, $MSE=0.55\%$). Conclusion : The data suggested that ultrasonography was a reliable method for measuring LSCD of masseter muscle in intra- and Interobserver and middle scan level showed the most reliable data.

• Imaging Science in Dentistry
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• v.46 no.2
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• pp.127-131
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• 2016

Purpose: This study was performed to compare the condylar position in patients with temporomandibular joint disorders (TMDs) and a normal group by using cone-beam computed tomography (CBCT). Materials and Methods: In the TMD group, 25 patients (5 men and 20 women) were randomly selected among the ones suffering from TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The control group consisted of 25 patients (8 men and 17 women) with normal temporomandibular joints (TMJs) who were referred to the radiology department in order to undergo CBCT scanning for implant treatment in the posterior maxilla. Linear measurements from the superior, anterior, and posterior joint spaces between the condyle and glenoid fossa were made through defined landmarks in the sagittal view. The inclination of articular eminence was also determined. Results: The mean anterior joint space was 2.3 mm in the normal group and 2.8 mm in the TMD group, respectively. The results showed that there was a significant correlation between the superior and posterior joint spaces in both the normal and TMD groups, but it was only in the TMD group that the correlation coefficient among the dimensions of anterior and superior spaces was significant. There was a significant correlation between the inclination of articular eminence and the size of the superior and posterior spaces in the normal group. Conclusion: The average dimension of the anterior joint space was different between the two groups. CBCT could be considered a useful diagnostic imaging modality for TMD patients.

• Journal of Family Resource Management and Policy Review
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• v.24 no.2
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• pp.1-21
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• 2020

The purpose of this research was, first, to classify work-life satisfaction among married wage workers aged 20-59 years into several distinct types based on two dimensions of work and life, using data from the 20th(2017) wave of the Korean Labor & Income Panel Study. Second, the study aimed to assess the differences in socio-demographic characteristics (sex, age, educational level, average monthly income), and workplace-related variables (weekly working hours, full-time employment, job stability, business type, family-friendly leave policies) by work-life satisfaction type. Accordingly, four types of work-life satisfaction were identified: work-life satisfaction, work-life dissatisfaction, work satisfaction, and life satisfaction. There was a significant difference in the type of work-life satisfaction among married waged workers based on sex, age, educational level, and average monthly income. Additionally, there was a significant difference in the type of work-life satisfaction for all workplace-related variables, namely, weekly working hours, full-time employment, job stability, business type, and family-friendly leave policies. In particular, proportionally higher values of work-life satisfaction were evident among the workers in companies with family-friendly leave policies such as paid leave, menstrual leave, maternity leave, childcare leave, and family events leave, whereas there was a high rate of work-life dissatisfaction among the workers in companies without family-friendly leave policies.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.107-113
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• 2013

Most natural river reach are approximately balanced with respect to sediment inflow and outflow. Dam construction dramatically alters this balance, creating an impounded river reach characterized by extremely low flow velocities and efficient sediment trapping. The impounded reach will accumulate sediment and lose storage capacity until a balance is again achieved, which would normally occur after the impoundment has become "filled up" with sediment and can no longer provide water storage and other benefits. This paper aims to investigate the sediment removal process in dam reservoir using simultaneously pressure flushing operation and vibrator machine. The main objective of this study is to identify the effect of vibrator in flushing cone dimensions. To achieve the objectives of present study, laboratory test have conducted under different hydraulic conditions such as two bottom outlets with diameter equal to 2" and 3", five discharges 0.23, 0.53, 1.21, 1.53 and 2.1 lit/s and only one water depth above the center of bottom outlets. Using the vibrator machine mounted into the reservoir and close to the bottom outlet, different frequency e.g. 20, 35 and 50 HZ, have been introduced to the deposited sediment at the vicinity of outlet. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations. The results indicate that the volume and width of flushing cone are strongly affected by frequency of vibrations.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.403-409
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• 2007

Contourlet transform is an extention of the wavelet transform in two dimensions using the multiscale and directional fillet banks. The contourlet transform has the advantages of multiscale and time-frequency-localization properties of wavelets, but also provides a high degree of directionality. In this paper, we propose a face recognition system based on fusion methods using contourlet transform and PCA. After decomposing a face image into directional subband images by contourlet, features are obtained in each subband by PCA. Finally, face recognition is performed by fusion technique that effectively combines similarities calculated respectively In each local subband. To show the effectiveness of the proposed method, we performed experiments for ORL and CBNU dataset, and then we obtained better recognition performance in comparison with the results produced by conventional methods.

• Journal of the Korean Geographical Society
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• v.48 no.3
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• pp.466-481
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• 2013

The purpose of this research is to propose a model for education for sustainable development (ESD) within the geography curriculum. The study consists of two parts. The first part discusses the normal view of a model to assess the curriculum, namely the content and the cognitive dimensions. The ESD component necessitates an action program with skills and citizenship considered as the Objective Dimension. The second part of the paper examines the means for adding the Objective Dimension which follows a taking action approach through knowledge, skills, and citizenship that are consistent with ESD goals. The research procedure applied the methodology of the Delphi process. The theoretical model was initially developed by the researchers based on current practices in geography assessment in South Korea and the U.S. The model was tested using the Delphi technique by high school geography teachers and geography education faculty members in both countries who were recognized experts in their field. The research complements the curriculum and instructional activities that have been under way with the United Nations Decade of Education for Sustainable Development (UNDESD). The model may be used to deliberate proposals for building an ESD component into existing assessment practices.