• Water for future
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• v.29 no.3
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• pp.217-228
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• 1996

A new routing computer model for the symmetric compound channel called the ASFMCS (Apparent Shear Force Muskingum-Cung Method in Symmetry) is developed. The Muskingum-Cunge routing method is adapted. The Apparent Shear Force(ASF) between the deep main channel and shallow floodplain flow is introduced while the flow is routed. The nonlinear parameter method is applied. The temporal and spatial increments are varied according to the flow rate. The adaptation of above schemes is tested against the routed hydrographs using the DAMBRK model. The results of general routing practice of Muskingum-Cunge Method (GFMC) are also compared with those of the above two models. The results of the new model match remarkably well with those of DAMBRK. The routed hydrographs show smooth variation from the inflow boundary condition without any distortions caused by the difference of cross-section shape. However, the results of GPMC, showing earlier rising and falling of routed hydrograph, have considerable differences from those of the ASFMCS and DAMBRK.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.10
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• pp.521-527
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• 2006

After various measuring methods and system were investigated, Rogowski colis for the measurement of parameters in current zero region were designed and manufactured. Using the Rogowski coils and a 38kV 40kA VCB (vacuum circuit breaker), at last the post-arc current has been successfully measured firstly. It was found that the Rogowski coils used in this study have good characteristics and propriety to measure the parameters of current zero. We realized that the data processing for evaluating the post-arc current from the experimental results needs much more careful attention than that for building the measuring technique and system. The magnitude of post-arc current and the falling time of it to zero are proportioned to the rate of current di/dt. The magnitude of post-arc currents were around $1{\sim}3A$ to the interruption current of $20{\sim}30kA$ in the model VCB.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.822-833
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• 2011

A Xe plasma flat lamp, which has been noticed as a new eco-friendly LCD (liquid crystal display) backlight, requires the improvement of the luminance and the luminous efficiency although it has several advantages. To improve the performance of a lamp, it is necessary to understand the effects of discharge variables on the luminous characteristics of the lamp. Since it is difficult to diagnose a lamp discharge experimentally, the numerical analysis can be used instead. In this study, the luminous characteristics of a planar type Xe plasma flat lamp were analyzed with the variation of an input voltage and a pulse frequency. The numerical analysis of a lamp discharge was then performed using a RCT (relaxation continuum) model and a LFA (local field approximation) model. The comparison with the experimental results showed that the RCT model is valid for the numerical analysis of the flat lamp. The numerical analysis also showed that the modifications of a high frequency component and a voltage falling rate in the input voltage waveform could improve the luminous characteristics of the lamp.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.67-71
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• 2019

All countries, including Korea, are currently experiencing the effect of rapid climate change. As a result, the cultivation area of many crops including wheat is changing, or productivity is falling sharply. If enough nitrogen is present in the soil, the increase in atmospheric carbon dioxide due to the greenhouse effect can lead to increased photosynthesis of plants, resulting in increased productivity. By contrast, a low proportion of nitrogen in soil does not increase production, often leading to the use of nitrogen fertilizers to increase crop productivity: this causes serious environmental pollution due to the leakage of nitrogen fertilizers used by crops. Increasing the understanding of the molecular level of the plant nitrogen use efficiency mechanism may contribute to increased productivity of crops and reduced of environmental pollution by nitrogen. In Korea, cultivars have developed 35 kinds of wheat, such as 'keumgang' and 'Chokyeong', which can be used for specific purposes such as baking or noodles. In this study we investigate 'keumgang' and 'Chokyeong' in order to elucidate the mechanism of nitrogen use ability of wheat and contribute to the reduction of environmental pollution by providing guidelines for the proper use of nitrogenous fertilizer.

• Journal of Appropriate Technology
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• v.6 no.1
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• pp.45-50
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• 2020

We developed the world's first wireless ultrasound diagnostic device. For the smooth delivery of pregnant women, the WHO requires four prior examinations, and the use of ultrasound diagnostic devices is essential for this purpose. However, income levels and medical facilities in developing countries are falling short. We conducted KOICA's CTS program in Vietnam using a self-developed radio ultrasound diagnostic device. We supplied Sonon300C, a portable wireless ultrasound diagnostic device, to health centers and hospitals in Huong-Hoa district, Vietnam, and conducted an outreach program in an effort to further enhance business performance. As a result, the rate of ultrasound diagnostics in the region reached 100% and the percentage of trained graduates increased to 59%.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.405-411
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• 2020

In this paper, we designed the COS MEMS system for sensing the falling detection and explosive noise of fuse link in COS (Cut Out Switch) installing on the power distribution. This system analyzed the failure characteristics and an instantaneous breakdown of power distribution. Therefore, our system strengths the industrial competence and guaranties the stable power supply. In this paper, we applied BLE (Bluetooth Low Energy) technology which is suitable protocol for low data rate, low power consumption and low-cost sensor applications. We experimented with LSM6DSOX which is system-in-module featuring 3 axis digital accelerometer and gyroscope boosting in high-performance mode and enabling always-on low-power features for an optimal motion for the COS fuse holder. Also, we used the MP34DT05-A for gathering an ultra-compact, low power, omnidirectional, digital MEMS microphone built with a capacitive sensing element and an IC interface. The proposed COS MEMS system is developed based on nRF52 SoC (System on Chip), and contained a 3-axis digital accelerometer, a digital microphone, and a SD card. In this paper of experiment steps, we analyzed the performance of COS MEMS system with gathering the accelerometer raw data and the PDM (Pulse Data Modulation) data of MEMS microphone for broadcasting the failure of COS status.

• Journal of Trauma and Injury
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• v.35 no.4
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• pp.232-239
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• 2022

Purpose: The recent increase in electric scooter (e-scooter) use has been accompanied by an increase in injuries from e-scooter-related accidents. Studies have reported that most such injuries are minor, and physicians may therefore underestimate the severity of such injuries. This study investigated the types and severity of injuries caused by isolated e-scooter accidents (i.e., those that did not involve colliding with other cars or falling from heights). Methods: This prospective observational study was conducted from May to December 2021 at Dankook University Hospital tertiary medical center. The demographic data of patients injured in isolated e-scooter-related accidents were collected. All injuries were categorized by body part. Results: Fifty eligible patients visited our emergency department during the study period. Of these, 76% were categorized as nonemergency, and 62% were discharged after initial evaluation and treatment at the emergency department. Another 10% were admitted to the intensive care unit (ICU) and 18% to the ward, with nine patients receiving at least one operation. The average hospital stays were 2.4 days in the ICU and 9 days in the ward. One death occurred due to traumatic brain injury (overall mortality rate, 2%). Multiple fractures of the left third through ninth ribs combined with lung laceration and fractures of T12 and L4 were noted. Conclusions: Various types and severities of injuries can occur in isolated e-scooter accidents. While most such injuries are minor, some will require ICU admission or surgery, and deaths can occur. Physicians should not underestimate the severity of such injuries.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1105-1117
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• 2023

In this study, the pressure drop behavior of single- and two-phase flows of air and water through the porous beds filled with uniform and non-uniform sized spherical particles was examined. The pressure drop data in the single-phase flow experiments for the uniform particle beds agreed well with the original Ergun correlation. The results from the two-phase flow experiments were analyzed using numerical results based on three types of previous models. In the experiments for the uniform particle beds, the data on the two-phase pressure drop clearly showed the effect of the flow regime transition with a variation in the gas flow rate under stagnant liquid condition. The numerical analyses indicated that the predictability of the previous models for the experimental data relied mainly on the sub-models of the flow regime transitions and interfacial drag. In the experiments for the non-uniform particle beds, the two-phase pressure loss could be predicted well with numerical calculations based on the effective particle diameter. However, the previous models failed to accurately predict the counter-current flooding limit observed in the experiments. Finally, we propose a relation of falling liquid velocity into the particle bed by gravity to appropriately simulate the CCFL phenomenon.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.153-161
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• 2022

Among all industries, the construction industry still remains a traditional one with low productivity due to its labor-intensive and field-dependent production system, its supplier-oriented industrial structure, and the disruption of the information flow between participants. In addition, the construction industry in South Korea has recently been required to transform itself according to social trends such as aging, the reduction of skilled workers, and the shortening of working hours, and the disaster and death rates in the industry, which are more than twice as high as those in other industries, are making it more necessary to solve chronic safety problems. Therefore, the purpose of this study is to grasp the actual condition of safety management on construction sites in South Korea and analyze cases of K-smart technology utilization for preventing safety accidents on construction sites. The study investigated and analyzed the following. First, construction sites in South Korea were analyzed by type of safety accident, by type of construction, and by construction contract amount. Second, the current status of accidents on small-sized construction sites with a high fatal accident rate and cases of safety accidents on construction sites were investigated. The results of the study are expected to contribute to the dissemination and spread of smart safety technology for not only identifying major factors in safety accidents that occur on construction sites but also preventing workers from suffering accidents.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.1
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• pp.47-56
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• 1999

As the density of logic gates of VLSI chips has rapidly increased, more number of I/O pins has been required. This results in bigger package size and higher packager cost. The package cost is higher than the cost of bare chips for high I/O count VLSI chips. As the density of logic gates increases, the reduction method of the number of I/O pins for a given complexity of logic gates is required. In this paper, we propose the novel I/O interface circuit using CTR (Constant-Transition-Rate) code to reduce 50% of the number of I/O pins. The rising and falling edges of the symbol pulse of CTR codes contain 2-bit digital data, respectively. Since each symbol of the proposed CTR codes contains 4-bit digital data, the symbol rate can be reduced by the factor of 2 compared with the conventional I/O interface circuit. Also, the simultaneous switching noise(SSN) can be reduced because the transition rate is constant and the transition point of the symbols is widely distributed. The channel encoder is implemented only logic circuits and the circuit of the channel decoder is designed using the over-sampling method. The proper operation of the designed I/O interface circuit was verified using. HSPICE simulation with 0.6 m CMOS SPICE parameters. The simulation results indicate that the data transmission rate of the proposed circuit using 0.6 m CMOS technology is more than 200 Mbps/pin. We implemented the proposed circuit using Altera's FPGA and confimed the operation with the data transfer rate of 22.5 Mbps/pin.