• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.479-488
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• 2003

Dual-band microstrip antenna is designed for industrial-scientific-medical(ISM) band of 2.4 GHz and 5.8 GHz using finite-difference time-domain method(FDTD). Cross patch 130 by aperture in the ground plane of microstrip line is proposed as radiation element of antenna which is 2 rectangular patch is overlapped. To design antenna, change of input impedance is examined by length change of aperture and stub. And center frequency and - 10 dB bandwidth are investigated by change of length and width in radiation element. Measured result about reflection loss confirm that agree well with simulation results of FDTD and IE3D. And 3 dB beam width, front to back ratio and maximum gain is presented by measuring radiation pattern of antenna in frequency 2.43 GHz and 5.79 GHz.

• Journal of Preventive Medicine and Public Health
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• v.32 no.1
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• pp.30-39
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• 1999

Objectives. This study was carried out to evaluate hearing impairment judgement and to investigate the differences in various diagnostic criteria for noise-induced hearing loss (NIHL) among workers who required for close observation (C). Methods. Out of 731,029 workers who had taken the specific periodic health examination in 1994, we used the audiometric data on 37,999 workers (C) eliminating the employees who had previous otologic problems. Many investigators have being using different criteria for the evaluation of hearing impairment. In this study, we used the criteria of early (1989-1994), current, compensation for NIHL in Korea, 2-, 3-, 4-divided classification and hearing loss at 4,000 Hz and compared the evaluation results. Results. The prevalences of C and workers who had occupational disease $(D_1)$ diagnosed for NIHL were 11.1 % and 0.44 %. There were significant difference in the prevalences of C and $D_1$, depending on different province of Korea. Pure tone averages (PTAs) were not appropriately applied in their evaluation 97% of workers whom we studied on were below the level of mild hearing loss judged by ISO standard. However, there were wide variations in the prevalence rate of mild hearing loss by diagnostic criteria. Thus, there were different judgements in determining the degree of NIHL depending on which diagnostic criteria were utilized. PTAs were found 20.54 (Rt) and 20.74 (Lt) when the method of 3-divided classification was applied for audiometric data. The degree of hearing impairment of the left ear was more severe than that of right ear. The prevalence of normal hearing threshold below 20 dB was 75.4% and the range of difference in both ear was below 10 dB. Right sided hearing threshold levels were 21.08 dB (500 Hz), 18.44 dB (1,000 Hz), 22.09 (2,000 Hz) and 52.36 dB (4,000 Hz). There was typical high frequency loss (C5-dip at 4,000 Hz) above 30 - 40 dB in normal hearing level. The increasing trend in hearing threshold level was gradually decreased by the increase of PTAs. The difference between PTAs and threshold at 4,000 Hz was about 10 dB. Conclusions. We could found that PTAs in the previous examination were not appropriately evaluated. This study revealed that they did not use unique criteria for managing the workers of NIHL. For the prevention of NIHL, it was found that the quality control on diagnosis and comprehensive management program were required, especially for those of hearing loss (C).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.305-312
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• 2018

This study was carried out to investigate euphausiid abundance in an acoustic survey from March 2010 to July 2010 to suggest reasonable usage and management of the euphausiid Euphausia pacifica in the coastal area of Guryongpo Pohang. The acoustic data were analyzed by the 2-frequency difference method and the distorted wave born approximation acoustical theoretical model, which is used for organisms of weak target strength with small scatter, such as euphausiid scatter, among other marine organisms. The distribution and monthly density of euphausiids were estimated in the survey area. The results show that the volume back scattering strength frequency difference for euphausiid was 13.91-7.6 dB, and their monthly averag density was $28.2g/m^2$.

• Journal of Preventive Medicine and Public Health
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• v.24 no.4 s.36
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• pp.496-506
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• 1991

A cross-sectional study was conducted to investigate the effect of long term noise exposure on blood pressure among steel mill workers. The workers participated in periodic medical examinations performed from August 27 to September 6 in 1990. Examined were 1,034 workers with high-level noise exposure(average $91.8{\pm}5.2dB(A)$) and 390 workers with low-level noise exposure(average $75.2{\pm}4.6dB(A)$). No significant difference was found in systolic or diastolic flood pressure between the two exposure groups. Prevalence of hypertension (${\geq}160mmHg\;systolic\;or{\geq}100mmHg\;diastolic$) was higher in a younger age group (${\leq}40$ years old) of high-level noise exposure than of low-level noise exposure. However, the difference was not statistically significant. Furthermore, in younger ages, prevalence of hypertension appeared to be higher in the hearing loss group (${\geq}25dB\;at\;1000Hz\;or{\geq}40dB$ at 4000Hz in at least one ear) than in the normal hearing group. From multiple regression analysis, hearing loss, body mass index, age, alcohol and family history of hypertension were proven to be predictors of diastolic blood Pressure (p<0.02). When regression was performed for each age group, hearing loss was a strong predictor of diastolic pressure in the younger age group (p<0.01).

• Culinary science and hospitality research
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• v.17 no.5
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• pp.241-252
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• 2011

The study was carried out to evaluate the anticancer effects in Korean soybean paste(doenjang) added with sun-dried salt(S-D), roasted salt(R-D), bamboo salt roasted once(B1-D) or bamboo salt roasted nine times(B9-D). In MTT assay, S-D, R-D, B1-D and B9-D exhibited a significant inhibitory activity(64-87% and 68-92%) against the proliferation of AGS human gastric adenocarcinoma cells by adding 0.05% and 0.1% of methanol extract. Among Balb/c mice injected with sarcoma-180 cells, the bodies, livers, spleens, kidneys and heart weight of the mice administered with 4 kinds of doenjang extracts were heavier than the non-administered ones of the group. However, no difference was found between the control and doenjang administered groups. Four kinds of doenjang inhibited significantly the tumor growth, especially R-D and B1-D showing an inhibition of tumor cell growth up to 97% by the administration of 1.0 mg/kg methanol extracts of doenjang. The activity of natural killer(NK) cells was relatively high in mice administered with four kinds of doenjang. Particularly, mice administered with R-D methanol extract showed a stronger activity of 88.2%. The activity of glutathione S-transferase(GST) in mice administered with four kinds of doenjang was higher than that of the non-administered group. In particular, the GST activity was the strongest in the group with B1-D. As these results indicate the various kinds of salt have different effects on the anticancer activity of doenjang.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.257-262
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• 2018

Avian pathogenic E. coli (APEC) causes severe economic losses in the poultry farms, due to systemic infections leading to lethal colisepticemia. It causes a variety of diseases from air sac infection to systemic spread leading to septicemia. Secondary infection contains opportunistic infections due to immunosuppression disease. Collibacillosis causes the great problems in the poultry industry in Korea. Thus, it is necessary to identify and classify the characteristics of E. coli isolate of chicken origin to confirm the diversity of symptoms and whether they are transmitted among the farms. Fragment analysis is identify the difference in the number of Variable-Number Tandem-Repeats (VNTRs) for genotyping. VNTRs have repeating structure (Microsatellite, Short tandem repeats; STR, Simple sequence repeats; SSR) in the chromosome. This region can be used as a genetic marker because of its high mutation rate. And various lengths of the amplified DNA fragment cause the difference in the number of repetition of the DNA specific site. The number of repetition sequences indicates the separated size of fragments, so the each fragments can be distinguished by specific samples. The results of the sample show that there is no difference in six microsatellite loci (yjiD, aidB, molR_1, ftsZ, b1668, yibA). There are differences among the farms in relation of the number of repetitions of other six microsatellite loci (ycgW, yaiN, yiaB, mhpR, b0829, caiF). Four (ycgW, yiaB, b0829, caiF) of these six microsatellite loci show statistically significant differences (P<0.05). It means that the analysis using four microsatellite loci including ycgW, yiaB, b0829, and caiF can confirm among the farms. Five E. coli samples in one farm have same SSR repetition at all markers. But, there are significant differences from other farms at Four (ycgW, yiaB, b0829, caiF) microsatellite loci. These results emphasize again that the four microsatellite loci makes a difference in the amplified DNA fragments, enabling it to be used for E. coli genotyping.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.201-210
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• 1996

In this paper, we analyzed performance of a symbol timing recovery scheme for 16QAM Radio system. As a symbol timing recovery scheme, both maximum amplitude method(MAM) and wave difference method(WDM) are analyzed employing a pulse shaping filter, such as raised cosine filter(RCF) and nonlinear filter(NLF). Simulation result shows that the jitter performance of MAM or WDM using NLF is better than that using square root RCF. In order to estimate and compensate for the Rayleigh fading PSAM(Pilot Symbol Assisted Modulation) and space diversity are also employed. Consequently, BER performance of about $10^{-4}$ is obtained for $E_b/N_o$= 20 dB.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.85-90
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• 2014

The purpose of this study is to analysis the 3 differential size of the interior space for impulse noise. To achieve this goal the 3 kinds (27, 35, $50m^3$) of interior space were performed comparing the impulse noise. Result of this study, the standard error of the mean peak sound pressure of value from 0.19 to 0.27dB and there was no significant difference (p<0.01). And B-duration is significant differences (P<0.01) range from 3.98 to 7.93ms. This is respectively less than 10ms. These findings are confirmed in accordance by the 3 differential space size of the indoor-impulse noise due to 0.3 dB or less, so there was no difference to the operational influence. And also below 100 Hz were found fundamental mode frequency analysis. Results were matched with calculated theoretical values.

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.330-335
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• 2016

This study was conducted to derive merchantable volume ratio for 5 major species such as Pinus Densiflora (Central Region). The data used for this study was from at least more than 1,300 trees of research data throughout the country. the study applied two estimation equations, which were the estimation equation for wood volume ratio representing total wood volume to total tree stem volume and the estimation equation for merchantability representing ratio of merchantable volume to total wood volume. The merchantable volume ratio was derived by multiplying those two estimation equations. In order to gain wood volume ratio(W) from DBH, $W=\frac{a_1}{1+a_2/D}+\frac{b_1}{1+b_2/D}$ model was used. Fitness index of it was more than 99% by species, and other test statistics also indicated the suitability of this equation enough. Merchantability (M) for wood volume applied $M=e^{a_1\(\frac{d}{D}\)^{a_2}}-(b_0+b_1D+b_2D^2+b_3D^3)$ model and fitness index was more than 96% by species. Merchantable volume ratio was assessed using those two estimation equations by each 5 species, and constructed a merchantable volume ratio table. In result, merchuntable volume ratio was little difference between stand types, but there was slightly different with the existing standard such as conifers of 85% and non-conifers of 70%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1081-1090
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• 2013

In this paper, a C-band 10 W power amplifier with internally matched input and output matching circuit is designed and fabricated. The used power transistor for the power amplifier is GaAs pHEMT bare-chip. The wire bonding analysis considering the size of the capacitor and the position of transistor pad improves the accurate design. The matching circuit design with the package effect using EM simulation is performed. To reduce the unsymmetry of IMD3 in 2-tone measurement due to the memory effect, the bias circuit minimizing the memory effect is proposed and employed. The measured $P_{1dB}$, power gain, and power added efficiency are 39.8~40.4 dBm, 9.7~10.4 dB, and 33.4~38.0 %, respectively. Adopting the proposed bias circuit, the difference between the upper and lower IMD3 is less than 0.76 dB.