• Journal of the Institute of Convergence Signal Processing
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• v.23 no.3
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• pp.137-142
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• 2022

Every year, the number of wild animals appearing in human settlements increases, resulting in increased damage to property and human life. In particular, the damage is more severe when wild animals appear on highways or farmhouses. To solve this problem, ecological pathways and guide fences are being installed on highways. In addition, in order to solve the problem in farms, horn repelling using sensors, installing a net, and repelling by smell of excrement are being used. However, these methods are expensive and their effectiveness is not high. In this paper, we used YOLO (You Only Look Once), an AI-based image analysis method, to analyze harmful animals in real time to reduce malfunctions, and high-brightness LEDs and ultrasonic frequency speakers were used as extermination devices. The speaker outputs an audible frequency that only animals can hear, increasing the efficiency to only exterminate wild animals. The proposed system is designed using a general-purpose board so that it can be installed economically, and the detection performance is higher than that of the devices using the existing sensor.

• Computers and Concrete
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• v.33 no.5
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• pp.559-572
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• 2024

Problems of under-sized dams (small dams with large basin area) could get worse under the global warming condition. This study evaluates the possible change of these problems with the Namgang Dam, an under-sized dam in Korea. For this purpose, first, this study simulates the dam inflow data using a rainfall-runoff model, which are then used as input for the reservoir operation. As a result, daily dam storage, dam release, and dam water supply are derived and compared for both past observed period (1973~2022) and future simulated period (2006~2099) based on the global warming scenarios. Summarizing the results are as follows. First, the inflow rate in the future is expected to be increased significantly. The maximum inflow could be twice of that observed in the past. As a result, it is also expected that the frequency of the water level reaching the high level is increasing. Also, the amount and frequency of dam release are to be increased in the future period. More seriously, this increase is expected to be concentrated on rather extreme cases with large dam release volume. Simply, the condition for flood protection in the downstream of the Namgang Dam is becoming worse and worse. Ironically, the severity of water shortage problem is also expected to become much worse. As the most extreme case, the frequency of no water supply was zero in the observed period, but in the future period, it becomes once every five years. Both the maximum consecutive shortage days and the total shortage volume are expected to become more than twice in the future period. To prevent or mitigate this coming problem of an under-sized dam, the only countermeasure at this moment seems to be its redevelopment. Simply a bigger dam with larger dam reservoir can handle this adverse effect more easily.

• Journal of Korean Public Health Nursing
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• v.4 no.2
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• pp.79-99
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• 1990

This study was conducted to identify the family problems of the in-patients and to analize factors Influencing to the family problems. The subjects for this study were 277 family members those who were giving care for the adult patients during hospitalized in general wards at Seoul National University Hospital in Seoul. Data were collected through interviews with the questionnaire from September second to September twentieth in 1989. The instrument used for this study was the family problems scale which was developed by the researcher. Analysis of data was done by frequency, percent, mean, t-test, ANOVA, Pearson-Correlation Coefficients, and Stepwise Multiple Regression Analysis. The results of this study are summarized as follows: 1. General characteristics of the care-giver in family. The average age of care-givers was 37.9 years, and the $26.4\%$ of monthly Income of family was 310,000-500,000 won group. The $93.5\%$ of family had taken the responsibility of caring for the patients instead of hiring the care-givers, and the $12.3\%$of the care-givers complained weakning of health status during care giving for the patients. The spouse took the largest part of responsibility of the care-giving services to the patient among the family members. 2. General characteristics of the patients. The average age of patient was 47 years, and the $80.9\%$ of patient was married status. The $39\%$ of patient was father in the position of family, and the $41.5\%$ had the responsibility to support their family before hospitalization. The average hospitalization period of patient was 24.3 day and the $50.9\%$ had admission experience. 3. The factors of family problems which were faced by the family were classified into six problems. The factors of family problems were ranked as follows; the first rank problem was related to care-giving for the patients. the second problem was resulted from the patients diseases, the theirds problem was related with adaptation to the hospital enviroments, the fourth problem was related to the arisen conflicts with medical team. the fifth problem was related to the change of family function. and the sixth problem was the financial problem. 4. The relationship between the family problems and the general charateristics of the care-givers showed that the nuclear type family was higher the family problems, that the admission period of patients became longer, and that the family who had the worse condition of health status of the care givers during care giving for the patients. From the above results, it was confirmed that the family care giving for patients was faced with some problems resulted from patient's illness, relation to the medical team, adaptation to the hospital enviroment, financial problem. change of family function, and care-giving for patients.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.97-103
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• 2014

Signal processing technique of linear frequency modulation-frequency shift keying (LFM-FSK) waveform has been introduced for rear view radars of an automobile. LFM-FSK waveform consists of two sequential stepped frequency waveforms with some frequency offset, and thus, can be used to generate inverse synthetic aperture radar (ISAR) images of rear view target of an automobile. However, ISAR images can often be blurred due to inter-pulse phase errors. To resolve this problem, one-dimensional (1-D) entropies of high resolution range profiles (HRRP) are minimized with the help of particle swarm optimization (PSO). The searching space used in PSO is adaptively adjusted by the use of information on the target's velocity obtained from LFM-FSK waveforms. Simulation results show that the proposed method can generate well-focused ISAR images.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.241-249
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• 2012

In the many countries, research about ultra wideband wireless transmission technique is widely studied for efficient utilization of frequency resource due to a sudden increase of demand of frequency resource all over the world. The ultra wideband communication system has the some specific advantages. First, it can transmit data with high speed, second short transmission range can increase the frequency reuse rate, and finally it has high security property. However, there is a interference between ultra wideband system and other communication system but study to solve this problem is insufficient. To efficient utilization of limited frequency resource, a novel frequency avoidance technique and setup the standardization of frequency interference must need. So, the purpose of this paper is that increases communication efficiency of microwave communication systems to analyze the technical trends for transmission of the low power device, and to research the implementation and technical research of wireless access network technique of wideband communication systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.399-407
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• 2010

SC-FDMA system uses DFT-spreading method for reducing the PAPR of OFDM signal, which improves the power efficiency. Block type pilot is used in SC-FDMA system. However, there are ICI due to the inevitable phase noise and frequency offset that can be generated from the Doppler frequency and inaccuracy between the transceiver oscillators. This ICI definitely degrades the BER performance. To overcome this problem and estimate the channel efficiently, we like to propose ICI compensation algorithm for the SC-FDMA system with comb type pilot. SLM method is additionally included for the PAPR reduction when pilot is assigned in comb type. Finally, it is confirmed that the ICI due to the phase noise and frequency offset is efficiently compensated by the suggested algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.245-250
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• 2014

This paper introduces the inverse synthetic aperture radar(ISAR) imaging technique for rear view target of an automobile, which uses both linear frequency modulation-frequency shift keying(LFM-FSK) waveform and monopulse tracking. LFM-FSK waveform consists of two sequential stepped frequency waveforms with some frequency offset, and thus, can be used to generate ISAR images of rear view target of an automobile. However, ISAR images can often be blurred due to non-uniform change rate of relative aspect angle between radar and target. In order to address this problem, one-dimensional(1-D) Lagrange interpolation technique in conjunction with angle information obtained from the monopulse tracking is applied to generate uniform data across the radar's aspect angle. Simulation results show that the proposed method can provide focused ISAR images.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.3
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• pp.291-299
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• 1991

We retrospectively reviewed 334 inpatients who sustained a total of 518 mandibular fractures and who ewer treated in our department between l980-1990. This results were obtained as follows : 1. In respect of incidence, there were the highest frequency in July, and the lowest frequency in May. The number of patients has not been increased year after year due to competition with other department in our hospital. 2. The age frequency was the highest in the 2nd decade(38.9%) and the ratio of man to women was 4.9 : 1. 3. The most frequent cause of mandibular fracture was traffic accident(43.4%), and the next was fall down(24.3%), fist blow(71%), industrial accident(21%) and others in order. In the traffic accident, autobicycle accident was 14.1%. 4. The most common location of mandibular fracture was symphysis(38.8%), condyle(20.7% ), angle(19.9%) and body(15.1%) were next in order of frequency. The classification by location of fracture, the frequency of single fracture was 54.8%. 5. In 334 patients of mandibular fracture, the frequency of associated injuries was facial laceration(58.4%), teeth injuries(37.7%), extremity injuries(13.2%) were next in order of frequency. 6. The patients arrived in hospital immediately within 24 hours after accident wee 61.4% of all. In respect of treatment, open reduction was 68.7% of all. 7. Complications including infection were present 11.1% of patient. Other complications inclued delayed healing malocclusion, malocclusion and neurologic problem.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.32-42
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• 2011

Frequency reuse among relay stations (RSs) in a down-link access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since the areas covered by the RSs or the base station (BS) may overlap, some mobile stations (MSs) at the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the cell degrades the quality of service (QoS) fairness among the MSs as well as the system throughput. Exclusive use of a frequency band division (orthogonal resource allocation) among RSs can solve this problem but would cause degradation of the system throughput. We observe a trade-off between system throughput and QoS fairness in the previously reported schemes based on frequency reuse. In this paper, we propose a new frequency reuse scheme that achieves high system throughput with a high fairness level in QoS, positioning our scheme far above the trade-off curve formed by previous schemes. We claim that our scheme is beneficial for applications in which a high QoS level is required even for the MSs at the border. Exploiting the features of a directional antenna in the BS, we create a new zone in the frame structure. In the new zone, the RSs can serve the subordinate MSs at the border and prone to interference. In a 3-RS topology, where the RSs are located at points $120^{\circ}$ apart from one another, the throughput and Jain fairness index are 10.64 Mbps and 0.62, respectively. On the other hand, the throughput for the previously reported overlapped and orthogonal allocation schemes is 8.22 Mbps (fairness: 0.48) and 3.99 Mbps (fairness: 0.80), respectively. For a 6-RS topology, our scheme achieves a throughput of 18.38 Mbps with a fairness of 0.68; however, previous schemes with frequency reuse factors of 1, 2, 3, and 6 achieve a throughput of 15.24 Mbps (fairness: 0.53), 12.42 Mbps (fairness: 0.71),8.84 Mbps (fairness: 0.88), and 4.57 Mbps (fairness: 0.88), respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.87-94
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• 2017

Hot stamping processes are possible for tensile strength 1.4 GPa but the strength reduction is appeared from the cooling performance unbalance. And the strength of roll forming process is below than that of hot stamping process owing to using the steel which is lower strength of boron steel. In this study, We provide roll forming process asssisted high-frequency induction heating to solve the problem of conventional one. The experiments were carried out at under various sill side part conditions: high-frequency induction heating conditions of 15, 18, 21, 24, 27 and 30 kW. The high-frequency induction heating temperature was checked with Infrared camera and the sill side parts of mechanical properties and microstructure were measured. The heating temperature of high frequency induction was measured to max $850^{\circ}C$ under the coil power of 30 kW. The tensile strength was 1.5 GPa and hardness was 490 Hv. The martensite structure was discovered under coil power of 30 kW. The weight of steel material sill side having thickness 1.5 mm and the boron steel sill side having thickness 1.2 mm were compared to weight effect. The boron steel sill side reduced 11.5% compared to steel. Consequently, manufacturing process of 1.5 giga-grade's sill side part was successfully realized by the roll forming assisted high-frequency induction heating methods.