• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.971-973
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• 1993

Deflection Yoke(the following, DY) is the important electric device of CRT which deflects R, G, B beans influencing magnetic field produced by yoke coils. Recently, DY is designed to the saddle/saddle type of coils, being proposed for high-definite and high-efficient CRT. This paper presents the optimization of pin-sectioned saddle coil's shape for minimizing gap between desired and practical deflections of electron beams by using Genetic Algorithm. Evolution Startegy is utilized in this paper, since evolution strategy is a kind of genetic algorithms finding the optimized values by choicing the better generation with comparing the parents and their children. Here, the children are generated by only mutations from the normal random variables. Evolution strategy has shown better powerful converge rate than the other genetic algorithms becuase of using only the mutation-operator.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.10
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• pp.669-678
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• 2008

When operating a complex facility, Fault Detection and Diagnosis (FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. In this research, FDD algorithm was developed using the general pattern classifier method that can be applied to centrifugal chiller system. The simulation model for a centrifugal chiller system was developed in order to obtain characteristic data of turbo chiller system under normal and faulty operation. We tested FDD algorithm of a centrifugal chiller using data from simulation model at full load performance and 60% part load performance. In this research, we presented fault detection method using a normalized distance. Sensitivity analysis of fault detection was carried out with respect to fault progress. FDD algorithm developed in this study was found to indicate each failure modes accurately.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.633-635
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• 2022

If an error occurs during operation of the video wall controller, the control system creates a log file and records the log. In order to minimize the load on the system due to log recording, the log level is set so that the log is not recorded as much as possible under normal operating conditions. When an error occurs, detailed logs are recorded by changing the log level to analyze and respond to the cause of the error. So work efficiency is reduced, and operator intervention is inevitable to change the log level. In this paper, we propose a model that automatically sets the log level according to the operating situation using Contextual Bandit.

• Journal of Digestive Cancer Research
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• v.11 no.2
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• pp.66-76
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• 2023

Endoscopy is an important noninvasive procedure for patients with gastrointestinal problems. However, surgical techniques are shifting to laparoscopic surgery, and changes in endoscopic findings after laparoscopic surgery differ from those after previous surgical methods. Postoperative endoscopic findings differ from normal anatomical structures, and findings reportedly vary depending on the type of surgical technique. Therefore, we aimed to summarize the surgical and endoscopic findings for each surgical method from the surgeon's point of view. The causes of gastric emptying delay, bleeding, afferent loop syndrome, or anastomosis leakage occurring after gastric cancer surgery can be identified via upper gastrointestinal endoscopy that is relatively less invasive than the surgical method. Regarding postoperative anastomosis leakage, endoscopy can directly evaluate the degree of leakage at the anastomosis site more accurately than computed tomography and enable immediate intervention. As endoscopy is less invasive than the surgical method, patients can be evaluated and treated more safely. However, coordination between the surgeon and the endoscopist is necessary to perform the procedures effectively. Therefore, reviewing the changes in surgical and endoscopic findings is important.

• Journal of Oral Medicine and Pain
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• v.30 no.1
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• pp.69-77
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• 2005

The purposes of this study were to develop and introduce a novel intraoral appliance for bruxism composed of power switch and biofeedback device and further to examine inter- and intra-reliability of the appliance prior to clinical tests. The newly-developed appliance consisted of detection sensors, a central processing unit (CPU), a reactor and a storage unit and a displayer. Compact-sized, waterproof switches were selected as bruxism detection sensor and any sensor activation by clenching or grinding event was processed at the CPU and transmitted, by radio wave, to the reactor and storage unit and triggered auditory or vibratory signal, subsequently producing biofeedback to the patient with bruxism. The data on bruxing event in the storage unit can be displayed on the computer, making it possible analyzing frequency, duration and nature of bruxism. Cast models were obtained from ten volunteers with normal occlusion to evaluate reliability of the appliances. For inter-operator reliability on the intraoral appliances, each operator of the two fabricated the appliance for the same subject and compared the minimal contact forces provoking auditory biofeedback reaction in vertical, lateral and central directions. Intra-operator reliability was also investigated on the appliances made by a single operator at two separate times with an interval of two days. Conclusively, the newly-developed appliance is compact and safe to use in oral circumstance and easy to make. Furthermore, it had to be proven reliability excellent enough to apply in clinical settings. Thus, it is assumed that this appliance with the processor and the storage of data and auditory or vibratory biofeedback function is available and useful to analyze and control bruxism.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.1
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• pp.57-66
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• 2002

Objective : This study was designed to investigate the interrelationship and clinical usefulness of sperm morphology by strict criteria (SM), acrosome reaction following ionophore challenge test (ARIC) and sperm penetration assay (SPA) using zona-free hamster ova as prognostic factors in in vitro fertilization. Materials and Methods: Semen samples were provided by 83 patients undergoing IVF. We first evaluated the differences between normal fertilization group and poor fertilization group on three andrologic tests. Secondly, we analyzed the relationship between the three andrologic tests and in vitro fertilization on IVF settings. Finally, we evaluated the effectiveness of the three andrologic tests as the prognostic indicators for fertilizing ability. Results: The fertilization rate of all men in the poor fertilization group was less than 30%; but there was no evidence that this poor fertilization was due to oocyte defects. The results of three andrologic tests were significatly higher in normal fertilization group. Fertilization rate (%) in vitro was highly correlated (p<0.001) with % normal sperm by SM, ARIC value (%), and SPA result. By using Receiver-Operator-Characteristic curve (ROC), we evaluated the effectiveness of these three tests. The sensitivity and specificity of SM, ARIC test and SPA in predicting fertilization potential in IVF setting were 76% and 75%, 84% and 90%, and 76% and 95%, respectively. Conclusion: Our data suggest that the three andrologic tests can be reliable tools as prognostic factors of sperm fertilizing ability. Among these test, ARIC test and SPA gave more accurate information on fertilizing capacity. ARIC test was shown to have a predictive value for fertilizing ability comparable to that of SPA that appears to be a simple and cost-effective addition to current andrology laboratory. Combined application of these three tests may give more information on predicting sperm fertilizing capacity.

• Journal of the Korean Dietetic Association
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• v.11 no.3
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• pp.365-374
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• 2005

This study was conducted to compare the validity of obese index among body mass index(BMI), waist to hip ratio(WHR), and waist circumference(WC) and to determine which is the best in relation to cardiovascular risk factors of middle aged Korean(40-64yr).Data from the 1998 Korean Health and Nutrition Survey were used(N=3380). Anthropometric indices and cardiovascular risk factors were measured. Chi-square test, analysis of variance following duncan's multiple range test, partial correlation analysis, and Receiver Operator characteristic(ROC) curves were used in the analysis. There was a significant increasing trend in WHR, systolic blood pressure(SBP), high density lipoprotein cholesterol(HDL), and fasting blood sugar(FBS) with age categories of male and in BMI, WC, WHR, diastolic blood pressure(DBP), SBP, total cholesterol(TC), low density lipoprotein cholesterol(LDL), triglycerol(TG), and FBS with those of female. Specially female had the characteristics of upper body fat and systolic blood pressure risk(p<0.05). Proportions of subjects with lifestyle factors related to cardiovascular risk in overweight or upper body fat group were higher than that of normal group. Higher proportions of subjects were practiced exercise in upper body fat group of male than in other groups. Among 7 cardiovascular risk factors in partial correlation analysis, BMI had the highest correlation coefficient in 6 risk factors in male, whereas WC in 4 risk factors in female. Mean of each obese index according to cardiovascular risk groups except smoker was higher than that of normal(p<0.05). These trends were shown in upper body fat group and female. In ROC analysis of 12 risk factors and health conditions, the largest area under curve among obese indices for risk factors were BMI in male and WHR in female. The optimal cutoff values of each index(BMI: WHR: WC) for one or more cardiovascular risk factors were 23.13: 0.89: 85.35 in male and 23.57: 0.84: 78.35 in female. The results showed that cardiovascular risk factors were prevalent in middle aged Koreans within normal limits of obese indices like another Asians. For the identification of cardiovascular risk factors of middle aged Koreans, BMI for men and WHR for women are appropriate indices. But it is recommended that BMI, WHR, and WC, all three indices should be considered, when using these indices.

• The Korean Journal of Nuclear Medicine
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• v.33 no.2
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• pp.131-142
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• 1999

Purpose: Either gated myocardial perfusion SPECT or attenuation corrected SPECT can be used to improve specificity in the diagnosis of coronary artery disease. We investigated in this study whether gating or attenuation correction improved diagnostic performance of rest/stress perfusion SPECT in patients having intermediate pre-test likelihood of coronary artery disease. Materials and Methods: Sixty-eight patients underwent rest attenuation-corrected T1-20l/dipyridamole stress gated attenuation-corrected Tc-99m -MIBI SPECT using an ADAC vertex camera (M:F=29:39, aged $59{\pm}12$ years, coronary artery stenosis ${\geq}70%$, one vessel: 13, two vessel: 18, three vessel: 8, normal: 29). Using a five-point scale, three physicians graded the post-test likelihood of coronary artery disease for each arterial territory (1:normal, 2: possibly normal, 3:equivocal, 4. possibly abnormal, 5: abnormal). Sensitivity, specificity and area under receiver-operating-characteristic curves were compared for each operator between three methods : (A) non-attenuation-corrected SPECT; (B) gated SPECT added to (A): and (C) attenuation-corrected SPECT added to (B). Results: When grade 3 was used as the criteria for coronary artery disease, no differences in sensitivity and specificity were found between the three methods for each operator. Areas under receiver-operating-characteristic curves for diagnosis of coronary artery disease revealed no differences between each modality (p>0.05). Conclusion: In patients at intermediate risk of coronary artery disease, gated SPECT and attenuation- corrected SPECT did not improve diagnostic performance.

• Journal of the Korea Computer Industry Society
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• v.9 no.1
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• pp.21-28
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• 2008

In this paper, the edge parameters were drawn from speaking image around lip and effective automatic lip reading system to recognize the Korean 'a/e/i/o/u' 5 owels were constructed using the parameter. Speaking images around lip were divided into $5{\times}5$ pane. In each pane the number of digital edge element using Sobel operator were evaluated. The observational error between samples was corrected by using normalization method and the normalized value is used for parameter In the experiment to convince the strength of parameter, 50 normal persons were sampled. The images of 10 persons were analyzed and the images of another 40 persons were experimented for recognition. 500 data are gathered and analyzed. Based on this analysis, the neural net system is constructed and the recognition experiments are performed for 400 data. The neural net system gave the best recognition result of 91.1%.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.258-264
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• 2007

Spatiotemporal changes of brain rhythmic activity at a certain frequency have been usually monitored in real time using scalp potential maps of multi-channel electroencephalography(EEG) or magnetic field maps of magnetoencephalography(MEG). In the present study, we investigate if it is possible to implement a real-time brain activity monitoring system which can monitor spatiotemporal changes of cortical rhythmic activity on a subject's cortical surface, neither on a sensor plane nor on a standard brain model, with a high temporal resolution. In the suggested system, a frequency domain inverse operator is preliminarily constructed, considering the individual subject's anatomical information, noise level, and sensor configurations. Spectral current power at each cortical vertex is then calculated for the Fourier transforms of successive sections of continuous data, when a single frequency or particular frequency band is given. An offline study which perfectly simulated the suggested system demonstrates that cortical rhythmic source changes can be monitored at the cortical level with a maximal delay time of about 200 ms, when 18 channel EEG data are analyzed under Pentium4 3.4GHz environment. Two sets of artifact-free, eye closed, resting EEG data acquired from a dementia patient and a normal male subject were used to show the feasibility of the suggested system. Factors influencing the computational delay are investigated and possible applications of the system are discussed as well.