• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.6 s.360
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• pp.28-33
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• 2007

The front-end system having a capable of 2x reading and writing of BD-R/Ra/ROM is developed. Its readability is improved by adopting 5-tap adaptive partial response maximum likelihood (PRML) with the PR(a,b,c,d,e) type channel. Due to the proposed PRML, less than $2{\times}10^{-4}$ of the bit error rate (BER) is achieved with radial and tangential tilt margin of over${\mp}0.6{\circ}$ on 25GB disc in 2x speed. The method of an optimum Power control (OPC) for stable writing of various BD-R/RE is proposed. The developed chip contains 14-million transistors in a $60mm^2$ dies, and is fabricated in $0.18-{\mu}m$ CMOS technology.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.143-150
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• 1993

Shallow sub-bottom reflection recorders are obtained using dual frequency (15/100 KHz). The main goal of this study is to enhance the resolving power and penetration for the sub-bottom reflection of the sub-marine seismic exploration. The Fresnel zones of spherical waves for the near-field are of great importance to reach the high resoluton. In case a target to detects than the Fresnel radius, a diffraction hyperbola on the recorder is observed. A larger attenuation of sand makes less penetration than the smaller attenuation of silt and clay. It is found that the selective frequency as well as the seismic energy generation is the most important factors for sub-marine exploration. This technique of using dual frequency sub-marine exploration may be applied to detect the sub-bottom sludge soil, ocean contamination and marine archaeological relics.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.192-197
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• 2008

The value of this paper is to use reduced size apparatuses to perform field measurement in order to identify and validate that the harmonic-current effects are due to the presence of self-excitation capacitance connected at stator's terminals of the studied SEIG. This paper has presented the measured electrical quantities of a three-phase $\Delta$-connected wind induction generator (WIG) under sudden connection and disconnection of resistive loads. An intelligent power-system recorder/monitor has been employed to measure three-phase voltages and currents of the studied system at the terminals of the studied WIG and the load. The measured electrical quantities have been analyzed. Total harmonic distortion (THD) of current using cumulative probability density function has been employed to determine the penetration of harmonic distortion at load side. The results show that the harmonic currents generated by the studied WIG can be severely amplified by the connected self-excited capacitance at the stator's terminals.

• Journal of Soil and Groundwater Environment
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• v.23 no.6
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• pp.37-45
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• 2018

The source of Chusan Spring water in the Ulleungdo is the precipitation in the Nari caldera basin, which permeates in the Trachitic pumice and tuff area and moves downward, outflowing at the lithologic boundary between the trachyte and Nari tuff. It is known that the discharge rate of the Chusan Spring is large enough to be used for the small hydroelectric power generation, but the exact discharge rate and hydrogeologic characteristics have not been known. The discharge rates of the Spring were measured 11 times, which ranged from $15,220m^3/d$ to $36,278m^3/d$. The discharge rates, measured by the automatic level recorder, for two-year period, were $20,000{\sim}38,000m^3/d$. The variation of discharge rates did not coincide with rainfall event, but showed daily increases of $3,000{\sim}5,000m^3/d$. The annual discharge rate excluding the evapotranspiration and the surrounding stream discharge corresponded to 70.6% of the annual precipitation of the recharge area. Therefore, meteorological observations at the Nari basin, rather than the Ulleung-do meteorological station, are more appropriate to properly interpret the discharge characteristics of the Chusam Spring and the recharge rate of the basin.

• The Journal of Korean Medicine
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• v.29 no.2
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• pp.107-115
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• 2008

Objectives: The objective of this study was to assess the effects of acupuncture applied at PC6 and SP4 points on heart rate variability (HRV) in normal subjects under mental stress Methods: 24 healthy male subjects were recruited and randomized to a treatment group (12 subjects) or a control group (12 subjects). Both groups performed a mental arithmetic stress test and then acupuncture needles were inserted on PC6 and SP4 for the study group. In the control group, they took sham acupuncture as a control. Heart rate variability (HRV) was measured during the whole study period by FM-150 (digital Holter ECG recorder). Results: In the both groups, low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) was significantly increased after mental stress. Acupuncture induced significant decrease in low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) which were increased after mental stress test. But sham acupuncture induced no changes. Results: In both groups, low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) significantly increased after mental stress. Acupuncture induced significant decrease in low frequency (LF) power and ratio of low frequency to high frequency (LF/HF) which increased after mental stress test. In contrast, sham acupuncture induced no changes. Conclusions: Acupuncture on PC6 and SP4 could be useful to decrease sympathetic activity and balance autonomic nervous system for those who are under stress.

• Journal of Fisheries and Marine Sciences Education
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• v.6 no.1
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• pp.11-19
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• 1994

The North Pacific midwater trawling which is one of the important fishing methods for Korean fishing industry is working in the Bering Sea and the sea near Kamchaka Peninsula. The catch by Korean midwater trawlers had been recorded about 300 thousands $^{M/_T}$ a year. Six types of midwater trawl net-ordinary midwater trawl net, super-V trawl net, super mesh trawl net, rope trawl net, super plus trawl net and kite trawl net-have been widely used by large trawlers above 1,500gt in size since 1982. Regarding the fishing efficiency, the super plus trawl net and kite trawl net were acknowledged as higher than other nets. Maximum mesh size of super-plus trawl net and kite trawl net ranges about 20m, whereas the length of net about 150m, and high-tech polyethylene is used as the material of rope part. The problems involved in the North Pacific midwater trawl net may be summarized as follows ; (1) The dimension of fishing gear is too big compared with the towing power of trawler. (2) The mesh size of the rope part is too big compared with that of the common netting part. (3) The net is often torn out in the connecting position of the rope part and the netting part. (4) The net is not matched with the trawler and the otter board in many trawlers, so the shape of the trawl gear in the water is instable. (5) The fish school located near head rope, ground rope and side rope in the net recorder is not caught in practice because of the net instability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.512-515
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• 2001

The heifer electrocardiograph is a widely progressing research which is used in judgement to existence for a heart disease and analyzes electric potential changes of heart movement during continuous living of everyday after attaching to body portable holler recorder for twenty-four hours. In order to obtain electrocardiogram clearly, it must eliminate that 60Hz power line interference, baseline wandering, noise of muscle constriction. In holter electrocardiogram, the most big problem which is recorded signal of ECG(electrocardiogram) is a baseline wandering elimination, which is occurred by rhythm of respiration and muscle constriction of part from attaching to an electrode. Such baseline is roughly irregular wandering and shaking up and down therefore the part of baseline wandering elimination is very important because it is difficult of ECG diagnosis. In this study, it is stabilized baseline wandering in analog part as implementation f real-time signal processing digital filter so it is applicable to analyze patient's heart disease by way of design of baseline wandering elimination system.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.411-414
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• 1997

This paper describes the design guideline, methodology and general specification of the developed 12 channel interpretive electrocardiograph. The developed 12 channel electrocardiograph consists of main module, patient module, DSP module, interface module, power/battery module, TFT color LCD and thermal recorder. The control panel of the system has full keyboard, rotate/push button, function key and unctional indicators. The graphic user interface program conveniently allows user to record, setup, store, manage ECGs. A variety of system configurations give it ability to make user favorable environment. This system also has a resting adult's ECG analysis program. The developed system and program will be continusely evolved using a database of clinically correlated ECGs.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.1
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• pp.26-45
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• 2001

The Flash memory market: is an exciting market that has quickly over the last 10 years. Recently Flash memory provides a high-density. truly non-volatile, high performance read write memory solutions, also is characterized by low power consumption, extreme ruggedness and high reliability. Flash memory is an optimum solution for large nonvolitilc storage operations such as solid file storage, digital video recorder, digital still camera, The MP3 player and other portable multimedia communication applications requiring non-volatility. Regardless of the type of Flash memory, Flash media management software is always required to manage the larger Flash memory block partitions. This is true, since Flash memory cannot be erased on the byte level common to memory, but must be erased on a block granularity. The management of a Flash memory manager requires a keen understanding of a Flash technology and data management methods. Though Flash memory's write performance is relatively slow, the suggested algorithm offers a higher maximum write performance. Algorithms so far developed is not suitable for applications which is requiring more fast and frequent accesses. But, the proposed algorithm is focused on the justifiable operation even in the circumstance of fast and frequent accesses.

• Korean Journal of Materials Research
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• v.16 no.12
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• pp.777-781
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• 2006

Recently, there are a lot of study to alternate polycarbonate which is being used as storage material in CD, DVD. In this study, we alternated polycarbonate with glass. We observed the change of shape in a surface of the glass which was focused by Nd:YAG Laser. The change of shape and property was studied by thermal mechanical analysis (TMA), UV-Vis spectrometer, AFM and SEM. According to Laser power and quantity of additives, the Bump's size and shape are showed differently. In high energy, the Bump will be transformed into Pit. And also according to CTE, $T_d$ and absorption ratio of glass, difference between Bump and Pit is confirmed. From these investigation, we could control that the minimum size of bump which is more useful shape than pit's is about 1.3 $\mu$m, H 70 nm, and it is near same the spot size.