• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.637-646
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• 2012

Recently, Wireless Sensor Networks (WSNs) are used in many applications. When sensor nodes are deployed on special areas, where humans have any difficulties to get in, the nodes form network topology themselves. By using the sensor nodes, users are able to obtain environmental information. Due to the lack of the battery capability, sensor nodes should be efficiently managed with energy consumption in WSNs. In specific applications (e.g. in intrusion detections), intruders tend to occur unexpectedly. For the energy efficiency in the applications, an appropriate algorithm is strongly required. In this paper, we propose tree-based routing algorithm for the specific applications, which based on the intrusion detection. In addition, In order to decrease traffic density, the proposed algorithm provides enhanced method considering link cost and load balance, and it establishes efficient links amongst the sensor nodes. Simultaneously, by using the proposed scheme, parent and child nodes are (re-)defined. Furthermore, efficient routing table management facilitates to improve energy efficiency especially in the limited power source. In order to apply a realistic military environment, in this paper, we design three scenarios according to an intruder's moving direction; (1) the intruder is passing along a path where sensor nodes have been already deployed. (2) the intruders are crossing the path. (3) the intruders, who are moving as (1)'s scenario, are certainly deviating from the middle of the path. In conclusion, through the simulation results, we obtain the performance results in terms of latency and energy consumption, and analyze them. Finally, we validate our algorithm is highly able to adapt on such the application environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1A
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• pp.33-43
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• 2010

Recently, users want to use real-time multimedia services, such as internet, VoIP, etc., using their IEEE 802.11 wireless lan mobile stations. In order to provide such services, a handoff among access points is essential to support the mobility of a node, in such an wide area. However, the legacy handoff methods of IEEE 802.11 technology are easy to lose connections. Also, the recognition of a disconnection and channel re-searching time make the major delay of the next AP to connect. In addition, because IEEE 802.11 decides the selection of an AP depending only on received signal strength, regardless of a node direction, position, etc., it cannot guarantee a stable bandwidth for communication. Therefore, in order to provide a real-time multimedia service, a node must reduce the disconnection time and needs an appropriate algorithm to support a sufficient communication bandwidth. In this paper, we suggest an algorithm which predicts a handoff point of a moving node by using GPS location information, and guarantees a high transmission bandwidth according to the signal strength and the distance. We implemented the suggested algorithm, and confirmed the superiority of our algorithm by reducing around 3.7ms of the layer-2 disconnection time, and guaranteed 24.8% of the communication bandwidth.

• The Journal of the Acoustical Society of Korea
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• v.33 no.2
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• pp.87-93
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• 2014

If one identifies the detailed distribution of pressure and axial velocity at a source plane, the position and strength of major noise sources can be known, and the propagation characteristics in axial direction can be well understood to be used for the low noise design. Conventional techniques are usually limited in considering the constant source characteristics specified on the whole source surface; then, the source activity cannot be known in detail. In this work, a method to estimate the pressure and velocity field distribution on the source surface with high spatial resolution is studied. The matrix formulation including the evanescent modes is given, and the nearfield measurement method is proposed. Validation experiment is conducted on a wide duct system, at which a part of the source plane is excited by an acoustic driver in the absence of airflow. Increasing the number of evanescent modes, the prediction of pressure spectrum becomes further precise, and it has less than -25 dB error with 26 converged evanescent modes within the Helmholtz number range of interest. By using the converged modal amplitudes, the source parameter distribution is restored, and the position of the driver is clearly identified at kR = 1. By applying the regularization technique to the restored result, the unphysical minor peaks at the source plane can be effectively suppressed with the filtering of the over-estimated pure radial modes.

• Genomics & Informatics
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• v.3 no.4
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• pp.166-171
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• 2005

Background: Smoking effects are relatively well-documented, especially on cancers and cardiovascular diseases. However, the direction and magnitude of association between smoking and obesity remain unclear. Conflicting results so far are thought to stem from the multiple confounding structure of smoking and other obesogenic life style characteristics. Methods: Cotwin control study is a genomic epidemiology design, in which the other twin (=cotwin) serves as a control of the twin. Cotwin control study, discordant for smoking habits can provide powerful evidence of association between smoking and obesity by completely matching genomic information, intrauterine environment, and almost all environmental factors. We selected 3,697 like-sex twin pairs (2,762 male and 935 female pairs) out of 63,666 pairs of adult twins in the existing Korea Twin and Family Register, whose smoking habits are discordant. We used the information of obesity as body mass index (BMI, $kg/m^2$) blood pressure, and blood cholesterol level at the time or later than the smoking information. Paired t-test was done to compare the smoking effects. Results: Lifetime smoking rate was 80.1 % (47.9 current smoker) for men and 10% (1.7% current smoker) for women. Among 2,762 and 935 male and female like-sex twin pairs, 363 male pairs and 20 female pairs correspond to the definition of smoker-nonsmoker pair. The male smokers demonstrated increase in BMI by 0.47, while female smokers show slight decrease (by 0.13), which were not statistically significant. Diastolic and systolic blood pressure, and cholesterol level were slightly increased among smokers by 1.85 mmHg, 0.62 mmHg, and 1.28 mg/dl for men. For women, the results show increase in diastolic blood pressure (3.42mmHg) and cholesterol level (1.25 mg/dl), and systolic pressure (8.17 mmHg). Conclusion: The results refute the possibility that smoking can reduce BMI. Considering the direct adverse effect of smoking, it should be emphasized that smoking do not decrease obesity and thus increase overall metabolic syndrome.

• Journal of Digital Contents Society
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• v.18 no.5
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• pp.859-868
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• 2017

The purpose of this study is to investigate the research trend of robot education for young children and elementary students as a basic study for the development of hands-on robot program for young children. Trends by year, research contents, and effectiveness of 155 dissertations and journal papers from 2006 to May 2016 related to robot education for young children and elementary students were analyzed. The results were as follows. In the research subject, research was conducted in the order of integrated education, attitudes and awareness research, and response research for young children and programming education, design development research, and integrated education for elementary students. In the research method, observational research and development research were the most common in young children and elementary students, respectively. In the effectiveness validation, research on social and emotional interaction and research on creativity were the most common in young children and elementary students, respectively. Based on the results of this study, the analysis provided basic data for the development of programs for young children's hands-on robot activities and suggested the direction and implications of robot education in connection with SW education of young children and elementary students.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.439-446
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• 2015

The turnout system, which determines the direction of the train, is not only a key system but also a vulnerable system. Failure of this system may lead to a delay of the train or even casualties. In this light, it is necessary to precisely the conditions of the turnout system. Currently, ROADMASTER of Germany is used as a diagnostic system in Korea. However, a new diagnostic system should be developed for optimized operation of the turnout system with maintenance that is suitable for the Korean railway environment. In this paper, a Fault Tree Analysis for the representative faults of the turnout system is conducted and physical quantities, which can be the cause of the fault, are classified according to the component and function. Also, the measuring factors for the monitoring are derived and a decision making theory is suggested. On the basis of the results, we propose a new turnout diagnostic system that can provide more driverse and precise information than the conventional system.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.4
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• pp.345-352
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• 2008

Purpose: This study was performed to evaluate the stress distribution in the bone and the displacement distribution of the miniscrew under orthopedic force with two different types of miniplate design as skeletal anchorage for orthopedic treatment. Materials and methods: Finite element models were made for 6-hole miniplate (0.8mm in thickness), which were designed in two different shapes-one is curvilinear shaped (C plate, Jeil Medical Co., Korea) and another, Y shaped (Y plate), fixed with 3 pieces of miniscrew 2mm-diameter and 6mm-long respectively. A traction force of 4 N was applied in $0^{\circ}$, $30^{\circ}$ and $60^{\circ}$ to imaginary axis connecting two unfixed distalmost holes of the miniplate. Results: The maximum von Mises stress in the bone was much greater in the cortical portion rather than in the cancellous portion. C plate showed greater maximum von Mises stress in the cortical bone than Y plate. The maximum displacement of the miniscrew was greater in C plate than Y plate. The more increased the angle of the applied orthopedic force, the greater maximum von Mises stress in the bone and maximum displacement of the miniscrew. It was observed that in C plate, the von Mises stress in the bone and displacement of the miniscrew were distributed around the distalmost screw-fixed area. Conclusions: The results suggest that Y plate should have the advantage over C plate and in the placement of the miniplate, its imaginary axis should be placed as parallel as possible to the direction of orthopedic force to obtain its primary stability.

• Korea Journal of Hospital Management
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• v.7 no.4
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• pp.172-192
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• 2002

The purpose of this study is to ascertain whether the effect of introduction of OCS(Order Communication System) to the hospital is satisfied or not comparing the anticipated effect with the actual effect. For this purpose, a domestic hospital which has introduced and has been operating OCS for several years was chosen. Based on the internal data of S Hospital prepared before introducing OCS, researcher has analyzed the basic direction, design standard and status of operation after the introduction of OCS, etc. After analyzing the status of operations of several departments using OCS and interviewing with the chiefs of pertinent departments, a survey form was designed. Actual survey and interviews were conducted by the researcher for weeks to know whether doctors, nurses, medical technicians and clerks of the patient management dept. were satisfied with OCS and to find if they have any recommendations to improve OCS. Based on the analysis of survey, the effect of OCS was evaluated whether it has satisfied the anticipated effectiveness. For the question if they feel convenient in using OCS, doctors, nursing staffs in charge of ward and the staffs of billing dept. has answered that they were all satisfied(100%). The answers for the same question were relatively high in the case of nurses in charge of outpatient and staffs of radiography. Of course, there have been some nurses and staffs who complained for the inconvenience. However, overall satisfaction was high on the average. Some common problems occurred after the introduction of OCS were frequent errors due to instability of OCS system, paralysis of function of hardware on data back-up system and redundant investment due to erroneous choice of DB program in setting DB. It was also pointed out that lack of computer education and low participation of medical staffs has resulted in failure of developing effective software. As a result, it has lowered the efficiency of OCS. For example, some works have to be done by hands even after OCS. Based on the result of this research, recommendations to maximize the effect of OCS were presented as follows. First, strong leadership of CEO and active cooperation of doctors are mandatory. Second, all the process of hospital work should be analyzed and be redesigned in more efficient ways. Third, OCS should be designed to be user-based system which can be used efficiently by all staffs of the hospital. Forth, prior to the operation of OCS, proper tests of the program and trainings of the pertinent staff are required. Fifth, prior to the selection of hardware, BMT(Bench Marking Test) should be conducted. Sixth, before introducing OCS, staffs in charge of OCS should visit many hospitals operating the OCS system and take their cases into account.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.31 no.1
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• pp.67-87
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• 2020

The purpose of this study is to analyze current status and teacher librarians' perceptions of school library space composition and indoor environment, and propose some methods for the school library to be a basic educational facility. The space most secured by the 126 teacher librarians who participated in the survey was the free reading area, and the space with the lowest level was the media production and group project area. The most important types of spaces for teacher librarians are the teaching area and the free reading area, while the recognition of the importance of media production and group project areas is relatively low. Among the elements of indoor environmental assessment, they showed that safety and comfort were the most important but diversity and flexibility were relatively less important. The result of this analysis is different from the school and library policy direction that emphasizes the learning commons and maker spaces. Teacher librarians still seem to appreciate the importance of traditional library space. Therefore, it is necessary to include the establishment and operation of maker spaces and learning commons in the teacher librarians training and retraining process. In addition, it is necessary to increase the participation of users such as teachers, students, and parents in space composition and interior design initiatives to increase the user's interior environment satisfaction.

• Korean Journal of Construction Engineering and Management
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• v.19 no.4
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• pp.21-33
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• 2018

In 2018, the real estate markets have hardly been transacted according to the government's tight regulations of real estates, and have the high possibility to reach a low hit due to the hike of loan interest rates following the U. S rise of base money rate. The key profits for the large construction companies mainly come from the overseas plant projects and the domestic non-governmental construction projects. They suffered a lot such as the lowering of their credit ratings due to the large losses caused by the frquent design changes and work delay. Even in the domestic non-governmental construction projects, the general business risks are on the rise due to the property marketing moving over to the decreasing phase. The small and medium sized security companies has realized a lot of operaring profits as they participated in the PF market to make up for the losses in the securities trading business. But, now as the housing market is not so good around the nation except Seoul and the financial states of large construction companies are not good enough, they can face the liquidity crisis if there happens the problems in the PF backed securities which they have handled. As Korean economy experienced the crisis in the savings banks before, it is recommended that Financial Supervisory Service proposes the preemptive control method and supervision direction to overcome the crisis.