• Structural Engineering and Mechanics
• /
• v.13 no.2
• /
• pp.231-239
• /
• 2002

The problem of dynamic analysis of truss structures based on probability is studied in this paper. Considering the randomness of both physical parameters (elastic module and mass density) of structural materials and geometric dimension of bars respectively or simultaneously, the stiffness and mass matrixes of the elements and structure have been built. The structure dynamic characteristic based on probability is analyzed, and the expressions of numeral characteristics of inherence frequency random variable are derived from the Rayleigh's quotient. The method of structural dynamic analysis based on probability is developed. Finally, two examples are given.

• ETRI Journal
• /
• v.40 no.6
• /
• pp.714-725
• /
• 2018

Destination-assisted jamming (DAJ) is usually used to protect confidential information against untrusted relays and eavesdroppers in wireless networks. In this paper, a DAJ-based untrusted relay network with multiple antennas installed is presented. To increase the secrecy, a joint optimization of beamforming and power allocation at the source and destination is studied. A matched-filter precoder is introduced to maximize the cooperative jamming signal by directing cooperative jamming signals toward untrusted relays. Then, based on generalized singular-value decomposition (GSVD), a novel transmitted precoder for confidential signals is devised to align the signal into the subspace corresponding to the confidential transmission channel. To decouple the precoder design and optimal power allocation, an iterative algorithm is proposed to jointly optimize the above parameters. Numerical results validate the effectiveness of the proposed scheme. Compared with other schemes, the proposed scheme shows significant improvement in terms of security performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.9
• /
• pp.4771-4787
• /
• 2019

Aimed at the disclosure risk of mobile terminal user's location privacy in location-based services, a location-privacy protection scheme based on similar trajectory substitution is proposed. On the basis of the anonymized identities of users and candidates who request LBS, this scheme adopts trajectory similarity function to select the candidate whose trajectory is the most similar to user's at certain time intervals, then the selected candidate substitutes user to send LBS request, so as to protect user's privacy like identity, query and trajectory. Security analyses prove that this scheme is able to guarantee such security features as anonymity, non-forgeability, resistance to continuous query tracing attack and wiretapping attack. And the results of simulation experiment demonstrate that this scheme remarkably improve the optimal candidate' trajectory similarity and selection efficiency.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2023.05a
• /
• pp.701-702
• /
• 2023

코로나 진행중에 오른 집값들과 월세는 학생들 또는 직장인들에게 크나큰 부담으로 다가오고 있다. 따라서 본 논문에서는 '구해줘 룸메즈' 플랫폼을 통하여 사용자들이 경제적 부담을 룸메이트와 나누며 추가로 성향 분석을 사용해 제약사항을 줄여주려 한다. User-based 협업 필터링의 문제점을 보완하고자 본 논문에서는 Item-based 협업 필터링을 통한 방식을 제안한다. 본 논문은 많은 2,30 대 청년들의 자취 혹은 독립 생활에 대한 금전적 부담감을 덜어줄 것으로 기대한다.

• Radiation Oncology Journal
• /
• v.26 no.3
• /
• pp.189-194
• /
• 2008

Purpose: We designed a water-based bolus device for radiation therapy in Kaposi's sarcoma. This study evaluated the usefulness of this new device and compared it with the currently used rice-based bolus. Materials and Methods: We fashioned a polystyrene box and cut a hole in order to insert patient's extremities while the patient was in the supine position. We used a vacuum-vinyl based polymer to reduce water leakage. Next, we eliminated air using a vacuum pump and a vacuum valve to reduce the air gap between the water and extremities in the vacuum-vinyl box. We performed CT scans to evaluate the density difference of the fabricated water-based bolus device when the device in which the rice-based bolus was placed directly, the rice-based bolus with polymer-vinyl packed rice, and the water were all put in. We analyzed the density change with the air gap volume using a planning system. In addition, we measured the homogeneity and dose in the low-extremities phantom, attached to six TLD, and wrapped film exposed in parallel-opposite fields with the LINAC under the same conditions as the set-up of the CT-simulator. Results: The density value of the rice-based bolus with the rice put in directly was 14% lower than that of the water-based bolus. Moreover, the value of the other experiments in the rice-based bolus with the polymer-vinyl packed rice showed an 18% reduction in density. The analysis of the EDR2 film revealed that the water-based bolus shows a more homogeneous dose plan, which was superior by $4{\sim}4.4%$ to the rice-base bolus. The mean TLD readings of the rice-based bolus, with the rice put directly into the polystyrene box had a 3.4% higher density value. Moreover, the density value in the case of the rice-based bolus with polymer-vinyl packed rice had a 4.3% higher reading compared to the water-based bolus. Conclusion: Our custom-made water-based bolus device increases the accuracy of the set-up by confirming the treatment field. It also improves the accuracy of the therapy owing to the reduction of the air gap using a vacuum pump and a vacuum valve. This set-up represents a promising alternative device for delivering a homogenous dose to the target volume.

• Korean Journal of Child Studies
• /
• v.33 no.4
• /
• pp.19-34
• /
• 2012

This study investigated the differences in time use patterns and psychological states across daily activity contexts and interpersonal contexts, depending on the levels of school maladjustment among elementary school students. Using the Experience Sampling Method (ESM), 107 elementary school 6th grade students' daily time use patterns and psychological states across daily contexts were measured six times a day over a period of 4 days. Using the school maladjustment scale, an internal problem based school maladjusted group and an external problem based school maladjusted group were identified and selected. The daily time use patterns and psychological states of both school maladjusted groups were compared to those of the adjusted groups. The principle findings are as follows: first, the school maladjusted group students' daily time use patterns across daily activity contexts or interpersonal contexts did not differ from those of the students from the school adjusted group. Second, the school maladjusted group students experienced more negative emotions, lower concentration levels, and lower motivation levels across daily contexts than the school adjusted group students. These differences in motivation between the external problem school maladjusted group and adjusted group, however, were greater in the schoolwork context compared to the other daily activity contexts. The findings were discussed in the contexts of the daily experiences of child school maladjustment.

• Journal of the Korean Society of School Health
• /
• v.20 no.1
• /
• pp.45-52
• /
• 2007

Purpose: The purpose of this study was to examine the types of school accidents and their first aids at Elementary, Middle, High Schools in a local area. Methods: The subjects were 1062 students who have had episodes of school accidents from 730 (Elementary = 429, Middle = 188, High = 113) schools in Chungnam province from January to December, 2006. Data were collected from accident-related record from school nurse and 'School Safety Fund', and analyzed using the SPSS Version 13.0 programs and the results and conclusions are as follows: Results: The proportion of school accidents occurred were in middle(0.43%), high(0.35%), primary(0.30%) school students. And the most frequent type of accident was fracture and then sprain. Most school accidents broke out in playground during resting time, and followed by physical education class. The most frequent cause of school accidents was carelessness and first aid was fixation the injury. Conclusion: Based on these findings, school-based and continuous safety education programs and emergency care system within school and in community can be suggested in collaboration with health-related resources. Further longitudinal study to identify causes and kinds of school accidents and can also be recommended.

• Journal of IKEEE
• /
• v.13 no.4
• /
• pp.23-27
• /
• 2009

Ohmic contact formation and etching processes for the fabrication of MBE (molecular beam epitaxy) grown GaSb-based p-channel HEMT devices on Si substrate have been studied. Firstly, mesa etching process was established for device isolation, based on both HF-based wet etching and ICP-based dry etching. Ohmic contact process for the source and drain formation was also studied based on Ge/Au/Ni/Au metal stack, which resulted in a contact resistance as low as $0.683\;{\Omega}mm$ with RTA at $320^{\circ}C$ for 60s. Finally, for gate formation of HEMT device, gate recess process was studied based on AZ300 developer and citric acid-based wet etching, in which the latter turned out to have high etching selectivity between GaSb and AlGaSb layers that were used as the cap and the barrier of the device, respectively.

• Korea Journal of Hospital Management
• /
• v.15 no.1
• /
• pp.1-12
• /
• 2010

This study was tried to evaluate the level of completeness and the accordance in electronic medical records by comparing paper-based medical record in doctor's admission records, discharge summary, and nursing information records. Medical records of inpatients of neurology department that the 100 paper-based medical records in 2004 and 100 electronic medical records in 2006 were targeted. Existence of record items and doctor-nurse record accordance were evaluated in doctor's admission record, discharge summary, admission nursing information record, and discharge nursing information record. There were not any differences between electronic medical records and paper-based medical records in doctor's admission record and discharge summary. Electronic medical records had less missing records than paper-based medical records in admission and discharge nursing information records. Electronic medical records showed higher accordance than the paper-based medical record in doctor-nurse record generally, but there were statistically differences in only medication, allergy, smoking, and drinking (p<0.05). In this study, it was verified that the quality of electronic medical records are better than paper-based records in nursing information record and doctor-nurse record agreement.

• Journal of Science Education
• /
• v.43 no.2
• /
• pp.227-238
• /
• 2019

In this study, we investigated the perception of elementary school students on inquiry activities and collaborative problem-solving ability in data-based scientific inquiry. For this purpose, 20 data-based scientific inquiry classes were conducted in 26 elementary school students in Gyeongnam City. After selecting the inquiry problem, students conducted an inquiry process to collect data using digital inquiry instruments. The following results were obtained through questionnaires and interviews after the classes: First, students perceived the step on 'inquiry design and execution' as the most useful in the data-based scientific inquiry. Second, students perceived that their scientific ability and cooperation improved through data-based scientific inquiry, with the selection of inquiry problems being the most difficult. Third, students perceived positively the improvement of cooperative problem-solving ability. From the above results, it was found that data-based scientific inquiry is necessary to improve the elementary school students' scientific inquiry ability and cooperative problem-solving ability. Based on this research, we hope that the development and research of various inquiry activities will provide opportunities for inquiry that can cultivate various abilities needed for students living in the future.