• Smart Media Journal
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• v.10 no.3
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• pp.31-38
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• 2021

It is hard to predict when and where a fall accident will happen. Also, if rapid follow-up measures on it are not performed, a fall accident leads to a threat of life, so studies that can automatically detect a fall accident have become necessary. Among automatic fall-accident detection techniques, a fall detection scheme using an IMU (inertial measurement unit) sensor attached to a wrist is difficult to detect a fall accident due to its movement, but it is recognized as a technique that is easy to wear and has excellent accessibility. To overcome the difficulty in obtaining fall data, this study proposes an algorithm that efficiently learns less data through machine learning such as KNN (k-nearest neighbors) and SVM (support vector machine). In addition, to improve the performance of these mathematical classifiers, this study utilized feature data aquired in the frequency space. The proposed algorithm analyzed the effect by diversifying the parameters of the model and the parameters of the frequency feature extractor through experiments using standard datasets. The proposed algorithm could adequately cope with a realistic problem that fall data are difficult to obtain. Because it is lighter than other classifiers, this algorithm was also easy to implement in small embedded systems where SIMD (single instruction multiple data) processing devices were difficult to mount.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.1
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• pp.25-35
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• 2023

Considering the non-linear behavior of structure and soil when evaluating a nuclear power plant's seismic safety under a beyond-design basis earthquake is essential. In order to obtain the nonlinear response of a nuclear power plant structure, a time-domain SSI analysis method that considers the nonlinearity of soil and structure and the nonlinear Soil-Structure Interaction (SSI) effect is necessary. The Boundary Reaction Method (BRM) is a time-domain SSI analysis method. The BRM can be applied effectively with a Perfectly Matched Layer (PML), which is an effective energy absorbing boundary condition. The BRM has a characteristic that the magnitude of the response in far-field soil increases as the boundary interface of the effective seismic load moves outward. In addition, the PML has poor absorption performance of low-frequency waves. For this reason, the accuracy of the low-frequency response may be degraded when analyzing the combination of the BRM and the PML. In this study, the accuracy of the analysis response was improved by adjusting the PML input parameters to improve this problem. The accuracy of the response was evaluated by using the analysis response using KIESSI-3D, a frequency domain SSI analysis program, as a reference solution. As a result of the analysis applying the optimal PML parameter, the average error rate of the acceleration response spectrum for 9 degrees of freedom of the structure was 3.40%, which was highly similar to the reference result. In addition, time-domain nonlinear SSI analysis was performed with the soil's nonlinearity to show this study's applicability. As a result of nonlinear SSI analysis, plastic deformation was concentrated in the soil around the foundation. The analysis results found that the analysis method combining BRM and PML can be effectively applied to the seismic response analysis of nuclear power plant structures.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.30-36
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• 2022

In this paper, when the lighting and communication functions of the visible light communication system are used at the same time, we propose a technique to reduce the dimming level and flicker of the lighting. Visible light communication must satisfy both communication and lighting performance. However, the existing data code method results in reducing the brightness of the entire lighting. This causes deterioration of lighting performance and flicker phenomenon. To solve this problem, in this paper, we propose an adaptive learning code allocation technique that allocates binary codes to transmitted characters and optimizes and matches the binary codes allocated according to the frequency of occurrence of alphabets in character strings. Through this, we studied a technique that can faithfully play the role of lighting as well as communication function by allocating codes so that the 'OFF' pattern does not occur continuously while maintaining the maximum dimming level of each character string. As a result of the performance evaluation, the frequency of occurrence of '1' increased significantly without significantly affecting the overall communication performance, and on the contrary, the frequency of consecutive '0' decreased, indicating that the lighting performance of the system was greatly improved.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.1-8
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• 2023

If there is a defect in the wheel bearing, which is a major part of the car, it can cause problems such as traffic accidents. In order to solve this problem, big data is collected and monitoring is conducted to provide early information on the presence or absence of wheel bearing failure and type of failure through predictive diagnosis and management technology. System development is needed. In this paper, to implement such an intelligent wheel hub bearing maintenance system, we develop an embedded system equipped with sensors for monitoring reliability and soundness and algorithms for predictive diagnosis. The algorithm used acquires vibration signals from acceleration sensors installed in wheel bearings and can predict and diagnose failures through big data technology through signal processing techniques, fault frequency analysis, and health characteristic parameter definition. The implemented algorithm applies a stable signal extraction algorithm that can minimize vibration frequency components and maximize vibration components occurring in wheel bearings. In noise removal using a filter, an artificial intelligence-based soundness extraction algorithm is applied, and FFT is applied. The fault frequency was analyzed and the fault was diagnosed by extracting fault characteristic factors. The performance target of this system was over 12,800 ODR, and the target was met through test results.

• Journal of Korean Academy of Nursing
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• v.25 no.2
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• pp.372-389
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• 1995

The frequency with which administration of chemotherapy for gynecological cancer treatment is used has increased along with the use of surgery and radiotherapy Among the various side effects of chemotherapy, stomatitis causes a problem of function and sensation in the oral cavity. This oral discomfort can be categorized into two components ; perceived oral symptoms and observed oral symptoms. If the oral problem continues, it may cause infection, bleeding and nutritional deficiencies. As a result of this condition, compliance with the treatment process can be affected as well as the prognosis for the cancer patients. But as the oral discorrfort usually appears after chemotherapy, it is often not reported to the health care personnel as a patient problem. Without problem identification of the oral discomfort and ability to assess the problem, effective intervention cannot be planned. Therefore, this study was conducted to identify the pattern and the degree of oral discomfort due to cancer chemotherapy and thus to provide data for identification of the patient problem and for nursing assessment. The design of this study was a longitudinal de-scriptive study The subjects were in - patients who received chemotherapy under the diagnosis of gynecological cancer between Mar. 15, 1994 and May 15, 1994 at a general hospital in Seoul, Korea. The number of subjects was 64 and they were divided into two groups, one of 41 (A : 5FU & Neoplatin), the other of 23(B : Neoplatin, Cytoxan, Adriamycin), according to the treatment regimen. The data were collected for 24 days using self-re-port instruments. The instruments were the 「Perceived Oral Symptom Assessment Tool」 and 「Observed Oral Symptom Assessment Tool」 developed by this researcher. Data were analyzed using the SPSS-PC program, ANOVA, t-test, paired t-test and the Pearson Correlation Coefficient were applied. The results of this study are as follows : 1. In A regimen the peak time for perceived oral symptom scores was the fifth day after chemotherapy, and the tenth day for observed oral symptom scores. Both of the problems started on first day of chemotherapy and were not resolved completely until the 24th day after treatment. 2. In B regimen, the peak time for perceived oral symptom scores was on the seventh day after chemotherapy, and the eighth day for observed oral symptom scores. It was noted that perceived oral symptom scores were higher than observed oral symptom scores consistently for 24 days. Both also started on first day of chemotherapy, and were not resolved completely until the 24th day after chemotherapy. 3. There were no differences statistically in perceived oral symptom scores between A and B regimen. The loss of appetite and xerostomia caused the most severe discomfort in both of these two groups. 4. The were no differences statistically in observed oral symptom scores between the A and B regi moil. In the A regimen, the highest observed symptom scores were the lips, gingiva, tongue and buccal membrane in that order. But in the B regimen, the highest observed symptom scores were tongue, lips, buccal membrane and gingiva in that order. 5. In A regimen, the patients who had gingival edema and dentures had significantly higher perceived oral symptom scores. And those who had gingival edema and bleeding, foul odor and aphthous stomatitis had significantly higher observed oral symptom scores. 6. In B regimen, the patients who had the experience of stomatitis in the last course of chemotherapy had significantly higher perceived oral symptom scores. Those who had gingival edema had significantly higher observed oral symptom scores. 7. In the A regimen there was no correlation between lab values for lymphocytes and albumin with perceived oral symptom scores and observed oral symptom scores. In the B regimen, there was a significant negative correlation between lymphocytes and albumin with the observed oral symptom scores, but not between perceived oral symptom scores and lymphocytes and albumin values. In conclusion, the nurse should expect that the patient undergoing chemotherapy will complain severely about subjective discomfort and before objective physical change is observed. Also the patients who have chronic oral problems such as dentures, gingival edema and bleeding, foul odor, aphthous stomatitis will complain of severe oral discomfort due to chemotherapy.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.2
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• pp.179-186
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• 2008

Purpose: Feeding problems are common for typically developing children and have negative effects on physical, behavioral, and cognitive development. The purpose of the current study was to examine factors related to childhood feeding problems for typically developing children via parental reports. Methods: The feeding questionnaire developed by the authors and the Childhood Eating Behavior Inventory (CEBI) were administered to 796 parents of children who recruited from 2 pediatric outpatient clinics (n=379) and community (n=417). Problem eaters (PE) were identified by parental report and frequency analysis was conducted for types of feeding problems and its severity, problem behaviors during mealtime, the feeding methods of the parents, and the need for treatment. Results: The CEBI scores were significantly different between the PE and non-problem eaters (NPE), which suggests that the parental reports were reliable. The younger children had more feeding problems than the older children. The most frequent and severe feeding problems were selective eating and longer mealtimes across all age groups. One-half of the children had more than one problem behaviors during mealtime. Most parents of PE used ineffective methods to deal with children's behaviors during meal time, such as cajoling, which was related to their increased level of stress. Many parents reported their children need professional help for the feeding problems. Conclusion: Feeding problems are prevalent among children, especially younger children. Children with feeding problems showed a number of problem behaviors during mealtime and parental coping methods appeared to be ineffective. The need for treatment was considerable, thus the characteristics of this population must be acknowledged for providing proper treatment and advice.

• Journal of Mechanical Science and Technology
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• v.16 no.7
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• pp.927-934
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• 2002

The HANARO ( High-flux Advanced Neutron Application Reactor) has been operated since 1995. The Cold Neutron (CN) hole was implanted in the reflector tank from the design stage. Before a vacuum chamber and a moderator cell for the cold neutron source are installed into the CN hole, it is necessary to measure exactly the size of the inside diameter and thickness of the CN hole to prevent the interference problem. Due to inaccessibility and high radiation field in the CN hole, a mechanical measurement method is not permitted. The immersed ultrasonic technique is considered as the best way to measure the thickness and the diameter of the CN hole. The 4-Axis manipulator was designed and fabricated for locating the ultrasonic sensors. The transducer of an ultrasonic sensor having 10 MHz frequency leads to high resolution as much as 0.03mm. The inside diameter and thickness of 550 points of the CN hole were measured using 2 channel ultrasonic sensors. The results show that the thickness and inside diameter of the CN hole is in the range of 3.3∼6.7mm and 156∼ 165mm, respectively. This data will be a good reference for the design of the cold neutron source facility.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.125-128
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• 2008

In this paper, a stand-type planar antenna of 900MHz RFID band is designed and fabricated. As the proposed antenna is stand-type use of air permittivity, Bandwidth used ground height at rectangle patch structure and coaxial feed line is widen. Also wideband width can solve problem that RFID tag attached to things happens frequency shift keying phenomenon by liquid, special metal, temperature, humidity etc. Bandwidth of fabricated antenna to VSWR less than 2 is satisfied 11.9% at $890MHz{\sim}1000MHz$. And proposed antenna is circular polarization antenna of operating characteristics that axial ratio is less than 2 and gain is 6dBi.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.230-241
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• 2008

Characteristics of transfer responses for arrays like triangle, hexagon and semicircle were investigated. To characterize the site near Izmit city with ambient noise measurement, dispersion curves of surface waves were derived with using array technique like F-K, High resolution F-K, MSPAC and H/V ratio was calculated. Also, MASW was surveyed to get the high frequency part of dispersion curves. The transition from fundamental mode to first high mode of surface waves for dispersion curve was observed. Dispersion curve of fundamental mode of ambient noise and first higher mode of MASW was used in inversion to get S-wave velocity structure of subsurface. None-unique problem of results of surface wave inversion was solved with comparison of result of refraction tomography performed with first arrivals of MASW data.

• Korean Institute of Interior Design Journal
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• no.36
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• pp.84-92
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• 2003

Schools should be a safe and comfortable environment for learning and studying. However, school facilities are usually used by many students during restricted time. These conditions such as many people, restricted time and space mold a chain of school accidents. In Korea, the school accidents are increasing annually and many students experience 'big or small incidents' and are exposed to 'potential accidents'. In this study, I investigated the present situation of the elementary schools' accidents in In-Cheon area, and analyzed the various characteristics of them. The accidents in elementary school have tendencies of occuring frequently in higher grade and boy students relatively. As analyzed in the place of accident, classrooms have a set of factors of accident, on the other hand, corridor and staircase show single distinct cause of safety problem. And also, the major portion of accidents is associated with the door in restroom and entrance space. In order to reduce the severity and frequency of school accidents, there should be needed multilateral and interdisciplinary approach. To achieve the safe school environments, this study focused on establishing a foundation of practical directions in designing elementary schools.