• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.561-575
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• 1994

Williams, M K., King, E., and Walford, Joan (1969). Brit. J. industr. Med., 26, 202-216. An investigation of lead absorption in an electric accumulator factory with the use of personal samplers. Thirty-nine lead workers and controls, in stable conditions of exposure, each wore personal lead-in-air samplers daily for two weeks. During the second week samples for blood lead, urinary lead, urinary coproporphyrin, urinary $\gamma$-aminolevulinic acid (ALA), the punctate basophil count, and haemoglobin were taken daily. Duplicate estimations were made on one day. The lead exposures of men doing almost identical jobs differed by ratios of up to four to one. This could be attributed on y to personal differences in working habits. The correlation coefficients and regression equations of the biochemical tests with lead-in-air and with each other were determined. The mean values and $95\%$ confidence limits of single determinations of some of the biochemical tests corresponding to the two commonly accepted TLVs of lead-in-air (0-20 and 0-15 mg./$m^{3}$) were calculated from the regression equations. For each biochemical test the variation due to analytical error, the variation from day to day within subjects and the residual variation about the regression on lead-in-air were calculated. Previous estimates of the latter are not known. Excessive confidence may be placed in an index of exposure due to its low coefficient of variation within subjects unless the coefficient of variation between subjects about regression is taken into account. The correction for specific gravity of estimations of lead and ALA in spot samples of urine was found to reduce slightly the residual variation between subjects about the regression on lead-in-air and to increase the correlations with lead-in-air and with the other biochemical tests, but these changes were not statistically significant. The modified method used for estimating blood lead and urinary lead is described and validated.

• Design & Manufacturing
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• v.12 no.1
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• pp.52-57
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• 2018

With the recent strengthening of environmental regulations and the need for cost reduction, excavators, a type of construction equipment, are being miniaturized while components are being developed in consideration of stability. In the case of excavator press parts, mainly high-strength steel sheets are being used to enhance stability and reduce weight. However, in the case of high-strength materials, there is a need to research product forming methods to reduce Springback in defects arising in parts assembly due to Springback that result from the internal residual stress that occurs in press forming being released after product forming. Accordingly, regarding the tank cover, an excavator press-forming part, this study selected a method to reduce distortion through analysis of the Springback occurrence rate and Springback causes through a forming analysis. A forming analysis was conducted for the Springback of the tank cover. Deformations of 13.714 mm in the upper part and 6.244 mm in the inner part of the product occurred, while wrinkles occurred on the sides of the product due to uneven thickness. A forming analysis was conducted for the major shapes of the product to investigate the causes of Springback. Distortion deformation due to the bead in the center of the product was confirmed to be a large factor. A Springback reduction method of correcting uneven thickness in the product sides, a Springback reduction method of removing the bead, and a correction method of restriking after the final forming were used in a forming analysis to determine the degree of Springback reduction. For the forming method to correct uneven thickness in the sides, deformation was reduced by 12% in the upper side compared to the existing model, but deformation in the inner side increased by 1%. For the restriking forming method, deformation decreased by 25% in the upper side and 13% in the inner side. For the bead removal method, deformation decreased by 28% in the upper side and 13% in the inner side, the largest Springback correction results. This indicates that the bead has a large affect on Springback.

• Journal of Chest Surgery
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• v.24 no.2
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• pp.115-122
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• 1991

From April 1986 to December 1989, 25 infants under the age of 12 months with tetralogy of Fallot were operated on. Age ranged from 3 to 12 months[mean 8.9$\pm$4.9 months] and mean body weight was 7.8$\pm$ 2.6kg. All the patients were deeply cyanotic, 12 of them experienced anoxic spell. Transannular patch was laid down in 19 patients, in 7 of them monocuspid patch was utilized. Postrepair P RV/LV was measured at operation room in 17 patients[mean 0.48$\pm$0. 14]. Hospital mortality was 20Yo. Causes of deaths include right ventricular failure and low cardiac output. The mortality was closely related with patient`s age and body surface area at operation. Also higher mortality was noticed in patients having major associated anomaly or previous palliative operation, preoperative management with propranolol and transannular repair. 18 patients were followed up for 12 to 50 months with a mean follow-up time of 24 months after operation. There were no late deaths and late ventricular arrhythmia or congestive heart failure was not detected as yet. Redo operation was performed in one case because of residual pulmonic stenosis. Considering several advantages of early primary repair, primary repair of symptomatic infants with tetralogy of Fallot should be encouraged despite somewhat high mortality rate as yet and better results could be anticipated along with improvement of myocardial protection method and postoperative care.

• Journal of the Korean Institute of Navigation
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• v.12 no.2
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• pp.23-32
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• 1988

This paper offers a method of magnetic compass adjustment for the vessel alongside the wharf using newly designed magnetic north former, which makes the same magnetic field-change as the turning vessel does. The characteristics of the magnetic north former was examined by observing the deviation curves of the magnetic compass installed on the compass deviascop at laboratory. The magnetic north former consists of A and B arms which hold the permanent bar magnets at the both ends of each arm. The arm is to rotae in the horizontal plane about the vertical axis fixed at the center boss of the magnetic compass and it is to compensate the horizontal plane about the vertical axis fixed at the center boss of the magnetic compass and it is to compensate the horizontal component of the earth's field. The B arm makes the artificial magnetic north around the magnetic compass for every ship's heading. The results of investigation are summarized as follows ; 1. The observation and correction of magnetic compass deviation can be done without swinging the ship, of the effect of D coefficient is negligible. 2. The residual deviation curve of the magnetic compass depends on the accuracy of deduced value of ship's multplier($\lambda$). 3. The errors due to the inaccuracy of deduced value of ship's multiplier change in the same way as the B and C coefficient do.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.103-110
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• 2024

In this paper, a test bed for real-time network Real-Time Kinematic (RTK) research was constructed using reference stations of the NGII. A group of candidate station networks was derived, including three stations in Seoul. The group consisted of four stations with a distance of less than 100 km between them. Among several candidates, a network composed of stations with short distances between them and demonstrating good data quality for all reference stations was selected as the test bed. After collecting real-time data in Radio Technical Committee for Maritime services (RTCM) format from the selected stations and conducting a noise analysis on measurements, mm-level carrier phase measurement noise was confirmed. Afterwards, the user set the reference station inside the test bed and analyzed the network RTK positioning performance of the MAC method using the GPS L1 frequency as post-processing. From the result of the analysis it was confirmed that the residual error for all users was within 10 cm after applying the correction. Additionally, after determining integer ambiguities through Least-squares AMBiguity Decorrelation Adjustment (LAMBDA), it was confirmed that the fix rate was 100%, and all ambiguities were resolved as true values.

• Journal of Welding and Joining
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• v.13 no.2
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• pp.96-105
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• 1995

A modified method for the analysis of short fatigue crack growth has been presented, and calculations based upon the modified method are compared with experimental results for S45C carbon steel. It is also shown that the modified method is in good agreement with experimental data. The proposed equation for the fatigue crack growth rates includes a material constant which relates the threshold level to the endurance limit, a correction for elastic-plastic behaviour and a means for dealing with the effects of crack closure. In this study one of the modifications is to substitute the Forman' s elastic expression of the stress intensity factor range into the geometrical factor The other is a consideration of the bending effect which is developed from the moment caused by the eccentric cross sectional geometry as the crack grows. Thus, this method is useful for residual life prediction of the mechanical structures as well as the welding structures.

• Journal of Food Hygiene and Safety
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• v.14 no.2
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• pp.201-215
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• 1999

Limited information is available on the acceptability of Korean MRLs(maximum residue limits) and the health risk based on the pesticide exposure by food intake. The aim of this study was to evaluate TMDI(theoretical maximum daily intake) and EDI(estimated daily intake) for Korean by using MRLs, food intake, residue data, and correction factors, and compare with ADI(acceptable daily intake) in order to estimate the health risk based on the pesticide exposure. The study was performed in three steps. In the frist step, the residual pesticides in each category of food were investigated using the pesticide residue analytical data(1995-96) from officially approved organizations and the analytical data for poultry was adopted from Korean food code method. In the second step, TMDI was estimated from MRLs and food factors, and was compared with ADI. In the third step, the effectiveness of each culinary treatment (washing, peeling, steaming, boiling, and salting) was evaluated and EDI was calculated using pesticide residue data, food factor, and correction factor by treatment. TMDI obtained from MRLs and food intake, and food intake was summed as 1,100.99 g, which was 79.1% of total consumption. The percent ratio of TMDI to ADI for 156 pesticides was mostly below 80% and only 30 pesticides exceeded the ADI. In particular, non-treated EDI from pesticide residue data and food intake was summed up to about 43 $\mu\textrm{g}$/day/capita, and the rank was procymidone(8.6 $\mu\textrm{g}$) > maleic hydrazide(8.2 $\mu\textrm{g}$) > EPN(3.7 $\mu\textrm{g}$) > deltamethrin(3.5 $\mu\textrm{g}$) > cypermethrin(3.0 $\mu\textrm{g}$). The treated EDI calculated from pesticide residue data, food intake, and correction factor by culinary treatment was summed up to 13.7 $\mu\textrm{g}$/day/captia. The percentage of ADI was TMDI(79.74%) > non-treated EDI (0.17%) > treated EDI (0.04%), and the exposure level of Korean population to whole pesticides was below the level to produce health risk. Oncogenic risk of five pesticides used in Korea whose oncogenic potency(Q*) was known were assessed from TMDI and treated EDI. Dietary oncogenic risk for Korean was estimated to be 2.0$\times$10-3 on the basis of TMDI, 8.3$\times$10-7 on the basis of treated EDI. The oncogenic risk from TMDI exceeded the risk level(1$\times$10-6) of EPA, whereas the oncogenic risk from treated EDI and real exposure level lower than that of EPA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.172-181
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• 2010

In this paper, we propose an adaptive block quantization method. The propose method perfrect reconstructs side information without high complexity in the encoder side, as transmitting motion vectors from a decoder to an encoder side. Also, at the encoder side, residual signals between reconstructed side information and original frame are adaptively quantized to minimize parity bits to be transmitted to the decoder. The proposed method can effectively allocate bits based on bit error rate of side information. Also, we can achieved bit-saving by transmission of parity bits based on the error correction ability of the LDPC channel decoder, because we can know bit error rate and positions of error bit in encoder side. Experimental results show that the proposed algorithm achieves bit-saving by around 66% and delay of feedback channel, compared with the convntional algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.763-770
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• 2002

Recognition of CW Morse signals can be divided into several phases such as detection of tones and spaces, signal processing for removing noise from detected signals, decision of tones/spaces, mapping a sequence of tones and spaces into characters, error correction of a character message with textual repetition. In this paper, in order to cope with signal fading effectively we propose a signal detection method of identifying peaks in the frequency domain and present techniques for combining multiple frequency peaks and for removing residual signal components and noise. LMS adaptive method is applied for decision of tones/spaces, and initial value setting and malfunctioning conditions are analyzed. In recognition experiments, we used CW Morse signals collected by radio receivers and found that the proposed method achieves good recognition performance even in severe fading conditions.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.447-452
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• 2013

Vessel traffic system uses multiple sea surveillance radars as a primary sensor to obtain maritime traffic information like as ship's position, speed, course. The systematic errors such as the range bias and the azimuth bias of the two-dimensional radar system can significantly degrade the accuracy of the radar image and target tracking information. Therefore, the systematic errors of the radar system should be corrected precisely in order to provide the accurate target information in the vessel traffic system. In this paper, it is proposed that the method compensates the range bias and the azimuth bias using AtoN information installed at VTS coverage. The radar measurement residual error model is derived from the standard error model of two-dimensional radar measurements and the position information of AtoN, and then the linear Kalman filter is designed for estimation of the systematic errors of the radar system. The proposed method is validated via Monte-Carlo runs. Also, the convergence characteristics of the designed filter and the accuracy of the systematic error estimates according to the number of AtoN information are analyzed.