• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.1A
• /
• pp.27-33
• /
• 2000

Gardner’s algorithm is one of the useful algorithm for NDD(Non-Decision Directed) symbol synchronization in PAM communications. But the algorithm has a weak point such as pattern noises increasing in multi-level PAM. To insert a pre-filter in the algorithm is able to reduce timing jitter and pattern noise. In this paper, we analyze statistical properties of NDD algorithm to find an optimal parameter of the pre-filter for improving timing jitter and PLL locking. As a simulation result, optimum value of pre-filter parameter, $\beta$, is 0.3 and 0.5 at the roll off factor of the channel, $\alpha$, is 0.5 and 1.0, respectively. Optimum parameters of the pre-filter for clock synchronization of all-digital 256-QAM demodulator is shown in the results.

• Journal of the Korea Safety Management & Science
• /
• v.18 no.1
• /
• pp.141-145
• /
• 2016

This study was to improve to utilization of non dosimetry measurements for X-ray radiography. Experiments was passed off varying the X-ray tube voltage and the thickness of the aluminum filter by actual dose. Calculated results was set to the first beam quality factors, calculated first correction coefficient by the Microsoft Excel program was set as the second beam quality factors. To make the non dosimetry measurements simply, the Excel program apply to the new beam quality factors, the error was compared to the previous studies, and the results verify the calculated value of smaller errors.

• The Journal of the Korea Contents Association
• /
• v.10 no.2
• /
• pp.258-267
• /
• 2010

This interest in radiation exposure makes increasing doctor's awareness and knowledge of radiation dose in patients during X-ray test important in reducing patient's uneasiness. However, very few facilities are equipped with measurement instruments. Therefore, an intensive study to find out patient dose using computational method has been initiated. This study used special features of the bit system and NDD-M and directly measured the output dose of diagnostic X-ray instruments used in Korea to create tables. Two different methods were found to be adequate when applied to cases when X-ray outputs were both known and unknown, and comparative experiments with real measurement doses were carried out. Presented methods were found to provide more accurate results compared to the bit system and NDD-M. Therefore, patient dose during clinical trials were found to be more easily acceptable to medical personnel in the radiation field in terms of radiation exposure and reduction of medical X ray dose.

• Imaging Science in Dentistry
• /
• v.32 no.2
• /
• pp.67-73
• /
• 2002

Purpose: To examine the possible relationship between condylar position and disk displacement in the temporomandibular joint. Materials and Methods: 79 temporomandibular joints in 40 patients having temporomandibular disorders were classified into three categories: no disk displacement (NDD) , disk displacement with reduction (DDWR), and disk displacement without reduction (DDWOR). Disk positions were assessed from clinical and MRI findings. The relationship between the three categories and condylar positions was evaluated using lateral individualized corrected tomography. Results: Clinical findings regarding the relationship between condyle and disk positions having anterior, centric, and posterior positions were 27%, 27%, and 46%, respectively, in NDD, 43%, 17%, and 40%, respectively, in DDWR, and 44%, 22%, and 34%, respectively, in DDWOR. There were no significant differences in condylar positions between each of the groups (P>0.05). In the relationship between condyle and disk positions with MRI findings, anterior, centric, and posterior positions were 38%, 38%, and 24%, respectively, in NDD, 29%, 21%, and 50%, respectively, in DDWR, and 44%, 9%, and 47% respectively, in DDWOR. There were significant differences in the condylar positions when MRI was utilized (P<0.05) Conclusion: There was a significant correlation between the condyle and disk positions with MRI findings on lateral individualized corrected tomography.

• Nutrition Research and Practice
• /
• v.8 no.6
• /
• pp.713-718
• /
• 2014

BACKGROUND/OBJECTIVES: Studies have indicated that university students majoring in nutrition and dietetics or sport sciences may have more obsessions associated with eating attitudes and body shape perception compared to other disciplines i.e. social sciences. Therefore, this study aimed to assess and compare the risk of eating disorders and body shape perception. MATERIALS/METHODS: Data was collected from 773 undergraduate students at the Departments of Nutrition and Dietetics (NDD) (n = 254), Physical Education and Sports (PESD) (n = 263), and Social Sciences (SOC) (n = 256).A socio-demographic and personal information questionnaire, Eating Attitudes Test (EAT-40), Body Shape Questionnaire (BSQ-34), Perceived Figure Rating Scale (FRS) were applied; and body weights and heights were measured. RESULTS: Mean EAT-40 scores showed that, both male and female students of PESD had the highest scores ($7.4{\pm}11.6$) compared with NDD ($14.3{\pm}8.3$) and SOC ($13.0{\pm}6.2$) (P < 0.05). According to EAT-40 classification, high risk in abnormal eating behavior was more in PESD (10.7%) compared to NDD (2.9%) and SOC (0.4%) students (P < 0.05). Students of PESD, who skipped meal, had higher tendency to the risk of eating disorders (P < 0.05). In parallel, body shape perception was found to be marked with higher scores in NDD ($72.0{\pm}28.7$) and PESD ($71.5{\pm}32.8$) compared with SOC ($64.2{\pm}27.5$) students (P < 0.05). Considering BSQ-34 classification, high concern (moderate and marked) for body shape were more in PESD (7.4 %) compared to NDD (5.2%) and SOC (1.9%) students (P < 0.05). The body size judgement via obtained by the FRS scale were generally correlated with BMI. The Body Mass Index levels were in normal range (Mean BMI: $21.9{\pm}2.8kg/m^2$) and generally consistent with FRS data. CONCLUSIONS: Tendency to the abnormal eating behavior and substantial body shape perception were higher in PESD students who have more concern on body shape and were not well-educated about nutrition. In conclusion, substantial concern on physical appearance might affect eating behavior disorders in PESD students.

• Journal of Radiation Industry
• /
• v.18 no.3
• /
• pp.183-193
• /
• 2024

As part of the social response to the radon bed incident in 2018, the Nuclear Safety and Security Commission took measures to collect and dispose of all radon beds. The Waste Management Act provides landfill disposal as one of the disposal methods for natural radioactive product waste, which is one of the NORM wastes. When NORM wastes are landfilled, workers and the public at the landfill site are exposed to radiation through various pathways, such as leaching of radionuclides through soil and groundwater, and multiple exposure factors are involved simultaneously. In order to improve the reliability of radiological impact assessment, the values of main exposure factors should be selected more accurately. Therefore, before developing the main exposure factors for site characteristics, it is necessary to prioritize main exposure factors reflecting domestic characteristics of NORM waste landfills. Therefore, in this study, the main exposure factors for NORM waste landfill were derived using NDD analysis. To derive the main exposure factors, the analysis tool was first selected as RESRAD-ONSITE computer code, and the exposure scenarios were mainly selected as a resident farmer and suburban resident scenario, recreation scenario, and industrial worker scenario. Then, the priority 1 and 2 factors were selected for sensitivity analysis, and a Korean standard model was established to reflect Korean characteristics. Finally, the sensitivity analysis was conducted through NDD, and the main exposure factors were derived based on this. In the resident farmer scenario, the contaminated zone distribution coefficients of ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Ra, ²³⁴U, and ²³⁸U, as well as precipitation and evapotranspiration factors, were derived as the main exposure factors. In the suburban resident scenario, the contaminated zone distribution coefficients of ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Ra, ²³⁴U, and ²³⁸U, as well as precipitation and evapotranspiration coefficients, were derived as the main exposure factors. In the recreation scenario, the contaminated zone distribution coefficient of ²³²Th was derived as the main exposure factor. For the industrial worker scenario, the erosion rate was derived as the main exposure factor. The main exposure factors for each scenario were analyzed to be different depending on the scenario characteristics. The results of this study can be utilized as a basis for radiological environmental impact assessment of NORM waste landfill in Korea.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1998.06a
• /
• pp.1184-1187
• /
• 1998

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.11a
• /
• pp.101-102
• /
• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.440-441
• /
• 2005

• Imaging Science in Dentistry
• /
• v.38 no.3
• /
• pp.153-161
• /
• 2008

Purpose : To compare and evaluate the diagnostic ability of cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ). Materials and Methods : CBCT and MRI of 46 TMJs of 23 patients with TMJ disorders were evaluated. They were divided into 3 groups according to the position of the articular disc of the TMJ at closed mouth position and the reduction of the disc during open mouth position on MRI: no disc displacement group (NDD), disc displacement with reduction group (DDR), and disc displacement without reduction group (DDWR). With PACS viewing soft-wares, position of mandibular condyle in the articular fossa, osseous change of mandibular condyle, shape of articular fossa, and mediolateral and anteroposterior dimensions of mandibular condyle were evaluated on CBCT and MRI. Each value was tested statistically. Results : The position of mandibular condyle in the articular fossa were concentric in the NDD, DDR, and DDWR of CBCT and NDD of MRI. However, condyle was positioned posteriorly in DDR and DDWR of MRI. Flattening, sclerosis and osteophyte of the mandibular condyle were much more apparent on DDR of CBCT than MRI. And the erosion of the condyle was much more apparent on DDWR of MRI than CBCT. Box and Sigmoid types of articular fossa were found most frequently in DDR of MRI. Flattened type was found most frequently in DDR of CBCT and deformed type was found most frequently in DDWR of CBCT. No significant difference in mediolateral and anteroposterior dimensions were shown on CBCT and MRI. Conclusion : Since MRI and CBCT has unique diagnostic imaging ability, both modalities should be used together to supplement each other to evaluate TMJ.