• Journal of the Korean earth science society
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• v.40 no.3
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• pp.272-282
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• 2019

Although the knowledge of current seismicity is a critical information for making and implementing effective earthquake-related policy, the detailed seismicity information of the metropolitan areas with high-population density has been largely underestimated due to the high-level of cultural noise and small earthquake magnitude. This study presents 12 earthquakes including 2 earthquakes previously known and 10 additional earthquakes occurred from 2010 to 2017 in Busan, but they were unreported by the Korea Meteorological Administration. Matched filter technique is used to detect micro-earthquakes. Although the epicenters of micro-earthquakes though present a distinguished linearity, a correlation with faults in the area is unknown. A repeated micro-seismicity suggests that there are subsurface structures responsible for observed events. If large earthquakes occur along the fault in Busan, they may cause catastrophic natural disasters. Given the fact that the recent earthquakes did not accompany any surface signatures, it is highly recommended that the current micro-seismicity be investigated, and updated seismicity information be incorporated into establishing active fault maps in Korea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.561-568
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• 2020

Wave measurements using X-band radar have many advantages compared to other wave gauges including wave-rider buoy, P-u-v gauge and Acoustic Doppler Current Profiler (ADCP), etc.. For example, radar system has no risk of loss/damage in bad weather conditions, low maintenance cost, and provides spatial distribution of waves from deep to shallow water. This paper presents new methods for estimating significant wave heights of X-band marine radar images using Artificial Neural Network (ANN). We compared the time series of estimated significant wave heights (Hs) using various estimation methods, such as signal-to-noise ratio (${\sqrt{SNR}}$), both and ${\sqrt{SNR}}$ the peak period (TP), and ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k). The estimated significant wave heights of the X-band images were compared with wave measurement using ADCP(AWC: Acoustic Wave and Current Profiler) at Hujeong Beach, Uljin, Korea. Estimation of Hs using ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k) yields best result.

• Korean Journal of Radiology
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• v.22 no.4
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• pp.624-633
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• 2021

Objective: To evaluate the reliability of CT measurements of muscle quantity and quality using variable CT parameters. Materials and Methods: A phantom, simulating the L2-4 vertebral levels, was used for this study. CT images were repeatedly acquired with modulation of tube voltage, tube current, slice thickness, and the image reconstruction algorithm. Reference standard muscle compartments were obtained from the reference maps of the phantom. Cross-sectional area based on the Hounsfield unit (HU) thresholds of muscle and its components, and the mean density of the reference standard muscle compartment, were used to measure the muscle quantity and quality using different CT protocols. Signal-to-noise ratios (SNRs) were calculated in the images acquired with different settings. Results: The skeletal muscle area (threshold, -29 to 150 HU) was constant, regardless of the protocol, occupying at least 91.7% of the reference standard muscle compartment. Conversely, normal attenuation muscle area (30-150 HU) was not constant in the different protocols, varying between 59.7% and 81.7% of the reference standard muscle compartment. The mean density was lower than the target density stated by the manufacturer (45 HU) in all cases (range, 39.0-44.9 HU). The SNR decreased with low tube voltage, low tube current, and in sections with thin slices, whereas it increased when the iterative reconstruction algorithm was used. Conclusion: Measurement of muscle quantity using HU threshold was reliable, regardless of the CT protocol used. Conversely, the measurement of muscle quality using the mean density and narrow HU thresholds were inconsistent and inaccurate across different CT protocols. Therefore, further studies are warranted in future to determine the optimal CT protocols for reliable measurements of muscle quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.793-800
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• 2004

In this paper, we propose a new automatic pipe grading algorithm for an efficient management of transmission pipe under the ground. Since the conventional transmission pipe evaluation was conducted by subjective decision made by an individual operator, it was difficult to grade them by means of numerical methods and also hard to realistically construct numerical database system. To solve these problems, we Int obtain some information on the current condition of pipes' sections by shooting laser beam at a regular rate and then apply grading algorithm after complete calculation of minimum diameter of pipe. We use some of preprocessing techniques to reduce noise and also use various color models to consider special conditions of each inner pipe. The measurement of pipes' minimum diameter and decision of grade are performed through a detailed processing stages. By some experimental results performed in the field, we show that over 90 percent of correct grade decisions are made by the proposed algorithm.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.5
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• pp.24-30
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• 2009

The Sin-Wol filtration plant was an urban infrastructure and off-limits to the public. It is recreated as a representative experiential theme park in the southwest area. It has not only provided places to relax, but has made a new model of urban park by reusing advantages. The current lack of easy access into the park area almost isolates it like a green island. The neighborhood surrounding the park does not have many physical connections to the park to be able to use it. By connecting the surrounding communities with numerous access points into the park and linking the hiking trails and bike paths, the city's need for open space and recreation would be far better satisfied than before. This would allow for the use of the valuable assets of the existing forest and open space.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.250-260
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• 2013

Objectives: The aim of this study is to analyze the current status of the possession of measurement and analytical instruments among work environment monitoring organizations that have been designated by the Ministry of Employment and Labor (MoEL) in Korea. Methods: Data for measurement and analytical instruments were gathered by inspectors who had been assigned by the Korea Occupational Safety and Health Agency (KOSHA) and MoEL during the evaluation program for designated work environment monitoring service providers in 2012. Data for 11 monitoring instruments and nine analytical instruments were collected from 108 organizations. Basic data such as the type of service provides and the size of employment were also recorded by the inspector. Results: The total number of personal air samplers including high and low flow rates operated in Korea was 5,418, with average of 50.2. Average operation number of noise dosimeters was 35.0, while 3,780 dosimeters were used in 108 work environment monitoring organizations. There were 10,488 monitoring instruments in total. All service providers possessed at least one AAS and GC in their analytical laboratory. Total number of HPLC/MS was five, followed by ICP/MS of seven, with an average of 0.07. Conclusions: Based on the data, domestic work environment monitoring service providers possessed relatively reasonable measurement and analytical instruments. Nearly all instruments had been imported from advanced countries such as USA, UK and Japan. Periodic gathering of data on these instruments may help maintain good workplace monitoring results and the health of workers at the sites.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.175-184
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• 2006

In this paper, we describe a 900MHz CMOS RF transceiver using an ISM band for ZigBee applications. The architecture of the designed rx front-end, which consists of a low noise amplifier, a down-mixer, a programmable gain amplifier and a band pass filter. And the tx front-end, which consists of a band pass filter, a programmable gain amplifier, an up-mixer and a drive amplifier. A low-if topology is adapted for transceiver architecture, and the total current consumption is reduced by using a low power topology. Entire transceiver is verified by means of post-layout simulation and is implemented in 0.18um RF CMOS technology. The fabricated chip demonstrate the measured results of -92dBm minimum rx input level and 0dBm maximum tx output level. Entire power consumption is 32mW(@1.8VDD). Die area is $2.3mm{\times}2.5mm$ including ESD protection diode pads.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.769-772
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• 2005

This paper describes a low-voltage and low-power channel selection analog front end with continuous-time low pass filters and highly linear programmable-gain amplifier(PGA). The filters were realized as balanced Gm-C biquadratic filters to achieve a low current consumption. High linearity and a constant wide bandwidth are achieved by using a new transconductance(Gm) cell. The PGA has a voltage gain varying from 0 to 65dB, while maintaining a constant bandwidth. A filter tuning circuit that requires an accurate time base but no external components is presented. With a 1-Vrms differential input and output, the filter achieves -85dB THD and a 78dB signal-to-noise ratio. Both the filter and PGA were implemented in a 0.18um 1P6M n-well CMOS process. They consume 3.2mW from a 1.8V power supply and occupy an area of $0.19mm^2$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.71-79
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• 2008

This paper analyzed the voltage induction phenomena on the telecommunication lines by electromagnetic coupling from high-speed A.C. electrified railway. The induced common mode voltages and the induced differential mode voltage on the telecommunication line was measured by notified standard method in the regulation of Korea. The test lines consist of 2 separated lines of 20 m and 300 m in influence distance each for comparison, with 2km inducing length. The analysis is made on the induced voltages from the different influence distances and the different earthing points, and also on the waveform and spectrum distributions. It is proved that the induction is arisen so good and the measured values are fair enough against noise such as the earth voltage differencing, and the current measuring scheme is also rightful.

• Ocean and Polar Research
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• v.42 no.2
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• pp.171-178
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• 2020

R/V EARDO, commissioned in 1992, has successfully carried out ocean research campaigns in Korean jurisdictional and adjacent waters, including continental margins and coastal zones within the Korean Exclusive Economic Zone (EEZ), for 29 years. However, it will soon be reaching the end of its useful service life. A replacement for R/V EARDO is urgently needed to ensure the safety of vessel itself and its crews, and efficient ship operation and maintenance, as well as to meet modern scientific mission requirements (SMRs). Basic specifications for a replacement ship have been devised and reviewed over the past nine months. A test of the proposed hull form was also performed. The total tonnage of the proposed vessel is approximately 740 tons, and the overall length and width are 62.0 and 11.6 m, respectively. The new ship will thus be 73% larger than the current R/V EARDO; in particular, the research workspace will be 4.4 times larger. The major design priorities are the propulsion system, efficiency of radiated noise and vibration control, and the dynamic positioning system. An environmentally friendly emission system, meeting International Maritime Organization (IMO) Tier III regulations, will be installed in the third exhaust pipe. Various wet and dry lab spaces as well as 32 different scientific instruments have also been considered in the ship design.