• Safety and Health at Work
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• v.2 no.4
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• pp.348-354
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• 2011

Objectives: This cross-sectional study was performed in the Dental School of Prince of Songkla University to ascertain noise exposure of dentists, dental assistants, and laboratory technicians. A noise spectral analysis was taken to illustrate the spectra of dental devices. Methods: A noise evaluation was performed to measure the noise level at dental clinics and one dental laboratory from May to December 2010. Noise spectral data of dental devices were taken during dental practices at the dental services clinic and at the dental laboratory. A noise dosimeter was set following the Occupational Safety and Health Administration criteria and then attached to the subjects' collar to record personal noise dose exposure during working periods. Results: The peaks of the noise spectrum of dental instruments were at 1,000, 4,000, and 8,000 Hz which depended on the type of instrument. The differences in working areas and job positions had an influence on the level of noise exposure (p < 0.01). Noise measurement in the personal hearing zone found that the laboratory technicians were exposed to the highest impulsive noise levels (137.1 dBC). The dentists and dental assistants who worked at a pedodontic clinic had the highest percent noise dose (4.60 ${\pm}$ 3.59%). In the working areas, the 8-hour time-weighted average of noise levels ranged between 49.7-58.1 dBA while the noisiest working area was the dental laboratory. Conclusion: Dental personnel are exposed to noise intensities lower than occupational exposure limits. Therefore, these dental personnel may not experience a noise-induced hearing loss.

• Economic and Environmental Geology
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• v.47 no.3
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• pp.219-225
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• 2014

In Korea, there are 1,474 thousand pumping wells nationwide which account for about 12% of total water use in 2012. As much as 39 hundred million tons of groundwater were used while 333 hundred million tons of total water were supplied in 2012. Because the water management authority projects that water demand will exceed supply by 2021, the authority is planning to extensively expand groundwater use in accordance with economic feasibility. Using the basic frameworks of cost-benefit analyses of the World Bank and the US Environmental Protection Agency (US EPA), the objective of this study is to examine the costs and benefits of the expansion of Korea's groundwater extraction through pumping wells. We conclude that the BC ratio of the groundwater pumping wells is 2.98. This signifies that the benefits are 2.98 times higher than the costs. The benefits include use and non-use values of pumping wells while the costs include the installation and maintenance of new wells, in addition to the restoration and pollution costs of abandoned wells, as well as fees for water quality tests, etc.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.339-345
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• 2016

This paper presents a two-stage power amplifier MMIC using a $0.4{\mu}m$ GaN-HEMT process. The two-stage structure provides high gain and compact circuit size using an integrated inter-stage matching network. The size and loss of the inter-stage matching network can be reduced by including bond wires as part of the matching network. The two-stage power amplifier MMIC was fabricated with a chip size of $2.0{\times}1.9mm^2$ and was mounted on a $4{\times}4$ QFN carrier for evaluation. Using a downlink LTE signal with a PAPR of 6.5 dB and a channel bandwidth of 10 MHz for the 2.6 GHz band, the power amplifier MMIC exhibited a gain of 30 dB, a drain efficiency of 32%, and an ACLR of -31.4 dBc at an average output power of 36 dBm. Using two power amplifier MMICs for the carrier and peaking amplifiers, a Doherty power amplifier was designed and implemented. At a 6 dB back-off output power level of 39 dBm, a gain of 24.7 dB and a drain efficiency of 43.5% were achieved.

• Korean Journal of Veterinary Research
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• v.14 no.2
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• pp.191-200
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• 1974

Hemoglobin, albumin and transferrin phenetypes observed in a population of 255 dogs of various breeds by agar gel electrophoresis for hemoglobin and albumin, and by starch gel electrophoresis, for transferrin. The results obtained were as follows: 1. The hemoglobin phenotypes were classified as HbAA, HbAB and HbBB and the frequencies of appearence were 91.77, 6.27 and 1.96%, respectively. Gene frequency studies of $Hb^A$ and $Hb^B$ showed the $Hb^A$ gene to have a frequency of 94.9% and $Hb^B$ gene to have a frequency of 5.1. The frequency of hemoglobin phenotypes of the Korean Jindo dog (ylelow) was HbAA 76.19%, HbAB 17.46% and HbBB 6.35% and HbBB was recognized only in the Korean Jindo dogs. 2. The albumin phenotypes were calssified as AlbAA, AlbAB and AlbBB and the frequencies of appearence were 28.71, 43.57 and 27.72% respectively. Gene frequency stduies of $Alb^A$ and $Alb^B$ showed the $Alb^A$ gene to hate a frequency of 50.50% and $Alb^B$ gene to have a frequency of 49.50. The frequency of albumin phenotypes of the Korean Jindo dog was 26.32% for AlbAA, 34.21% for AlbAB and 39.47% for AlbBB. The frequency of albumin phenotypes of the Korean Jindo dog was slightly different from others and gene frequency of $Alb^B$ was 56.58. 3. Transferrin studies resulted in findings of 10 different phenotypes and frequencies of transferrin phenotype were 30.08% for $TfA_1A_1$, 8.02 for $TfA_2A_2$, 2.11 for TfBB, 4.64 for $TfC_1C_1$, 1.69 for $TfA_1B$, 41.35 for $TfA_1C_1$, 5.49 for $TfA_2C_1$, 0.84 for $TfA_2C_2$ and 3.79 for $TfBC_1$. Gene frequency studies of $Tf^A$, $Tf^B$ and $Tf^C$ showed the gene to have a frequency of 63.08% for $Tf^A$, 4.85 for $Tf^B$ and 32.07 for $Tf^C$ 4. Transferrin studies revealed two different band patterns on starch gels with a strong and weaker stained one. The $TfC_2C_2$ and $TfA_2A_2$ which were found in the Korean Jindo dog only showed a weaker stained band and the gene frequency of $TfA_1A_1$ was highly recognized in this dog.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.802-809
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• 2014

This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a $0.18-{\mu}m$ CMOS process for the 1.75 GHz band. For the 16-QAM LTE signal with a peak-to-average power ratio of 7.3 dB and a bandwidth of 5 MHz, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 dB, and an adjacent channel leakage power ratio of -30 dBc at an average output power of 22 dBm, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 dBm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.484-494
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• 2014

We describe a digitally controlled oscillator (DCO) which compensates the frequency variations for process, voltage, and temperature (PVT) variations with an accuracy of ${\pm}2.6%$ at 2.5 GHz. The DCO includes an 8 phase current-controlled ring oscillator, a digitally controlled current source (DCCS), a process and temperature (PT)-counteracting voltage regulator, and a bias current generator. The DCO operates at a center frequency of 2.5 GHz with a wide tuning range of 2.2 GHz to 3.0 GHz. At 2.8 GHz, the DCO achieves a phase noise of -112 dBc/Hz at 10 MHz offset. When it is implemented in an all-digital phase-locked loop (ADPLL), the ADPLL exhibits an RMS jitter of 8.9 ps and a peak to peak jitter of 77.5 ps. The proposed DCO and ADPLL are fabricated in 65 nm CMOS technology with supply voltages of 2.5 V and 1.0 V, respectively.

• The Journal of Internal Korean Medicine
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• v.39 no.1
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• pp.84-96
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• 2018

Objective: This is aprospective clinical case study that includes the administration of Ahnjeonbaekho-tang (AJBHT) to patients who have suffered from Graves' disease for the 8 weeks of the clinical research. Methods: Without administration of an antithyroid drug, AJBHT was administered 3 times a day for 8 weeks. In Case 1, AJBHT without modification was administered and in Case 2, in accordance with the patients' symptoms, a dose of Gypsum Fibrosum was increased by 4g from the beginning of week 2, and further increased by 16 g, for a total of 20 g between week 6 and week 8. Body mass index (BMI), thyroid function test (TFT), thyroid autoantibody test, complete blood cell count (CBC), and blood chemistry (BC) tests were conducted at an interval of 4 weeks, for a total of 3 times during the study. The clinical manifestations, a spectrum of symptoms of the patients, was observed by Wayne's Index, Euro-QOL-5 Dimension (EQ-5D), and Perceived Stress Scale (PSS). Results: In both cases, an acceptable significance of reduction of value in T3, fT4, Thyroid stimulating antibody (TSAb) and Thyroid stimulating hormone receptor antibody (TSH-R-Ab) was observed. After treatment, in TFT, T3 decreased by 31.66%, fT4 decreased by 32.82% in Case 1, and T3 decreased by 43.42%, and fT4 decreased by 37.32% in Case 2. In the thyroid autoantibody test, TSAb decreased by 7.59%, and TSH-R-Ab decreased by 53.19% in Case 1, and TSAb decreased by 33.45%, TSH-R-Ab decreased by at least 7.75% in Case 2. Besides this, there was a decreasing trend of Wayne's index, and a loss of typical symptoms of hyperthyroidism also declared the efficacy. Conclusion: From these results, AJBHT is very effective in the regulation of TFT and improving the symptoms of hyperthyroidism, and is also expected to be an effective alternative to antithyroid drugs for patients who have side effects or drug intolerance.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.451-457
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• 2007

Four parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effects of varying an HRT of anoxic reactors and packing Bio contact media (BCM, fixed beds) in aerobic reactors on organic matter removal and nitrification/denitrification efficiencies. All systems were operated under conditions that the external recycle ratio was kept 0.5 Q while the internal recycle ratio was changed 1.0 Q to 1.5 Q with that $NH_4-N$ concentration of feed was increased to 40 mg/L by adding $NH_4Cl$. In terms of TSS and TCODcr removal efficiency, both systems with BCM and a system without BCM, respectively, had a similar level of the removal efficiency under varied HRTs of anoxic reactors (0.6 hr, 1.3 hr, 2 hr, 2 hr; control, without BC M) showing that varying an HRT of anoxic reactors did not affect the removal efficiency. While SCODcr removal efficiency of systems with BCM was improved approximately 4~5% at the same HRT of anoxic reactor, the removal efficiency of system with BCM was slightly decreased by reducing an HRT of anoxic reactor. The nitrification efficiency for both systems with BCM and a system without BCM was above 94% showing that packing BCM in aerobic reactors and varying an HRT of anoxic reactors did not affect the efficiency significantly despite of increasing $NH_4-N$ concentration of feed. The denitrification efficiency increased from 81.4% to 85.4% at system with BCM while the efficiency decreased when a shorter HRT of anoxic reactors was kept. The excellent effluent quality for $NO_3-N$ concentration was observed although the $NO_3-N$ concentration increased in anoxic reactors that $NH_4-N$ concentration of feed sufficiently converted into nitrate through nitrification. As a result, packing 20% BCM to an aerobic reactor with HRT of 1.3 hr of anoxic reactor in $A^2/O$ system can achieve a similar level of nitrogen removal efficiency in $A^2/O$ system which the aerobic reactor had no BCM and HRT of 2 hr for anoxic reactor is maintained.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.387-395
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• 2018

This study was conducted to identify DNA markers related to resistance to herbicide containing mesotrione in Tongil type rice. Two Tongil type elite lines; Milyang154 and Suweon382, showed resistance to mesotrione, whereas the others were susceptible at 20 days after mesotrione application, and severe growth inhibition was observed in the remaining 13 lines. As a result of analysis of mesotrione resistance using 190 $F_2$ populations derived from a cross of Hanareum2 (susceptible) and Milyang154 (resistant), the mesotrione resistance locus was shown to be a single dominant gene with a 3:1 segregation ratio ($X^2=1.19$, P=0.31). To identify a DNA marker closely linked to the mesotrione resistance gene, bulked segregant analysis (BSA) was adopted. The DNA marker RM3501 was identified on chromosome 2 with a recombinant value of 0.53 to the mesotrione resistance gene. Mst1(t) was located between SSR (simple sequence repeat) markers RM3501 and RM324 with a physical map distance of 10.2 Mb-11.4 Mb on chromosome 2. The band pattern of agarose gel electrophoresis of the SSR marker RM3501 showed the same segregation pattern with respect to mesotrione treatment in 20 Tongil type varieties and a $BC_2F_2$ segregation population derived from a cross between Unkwang (resistant) and Hanareum2 (susceptible). Thus, the RM3501 DNA marker could be used in breeding programs for Marker Assisted Selection in mesotrione resistant rice breeding.

• Journal of Service Research and Studies
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• v.13 no.1
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• pp.108-126
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• 2023

This study explored the sustainability of a blockchain-based cultural art performance video platform through the construction of Gyeonggi Art On, a new media art broadcasting station in Gyeonggi-do. In addition, the technical limitations of video content transaction using block chain, legal and institutional issues, and the protection of personal information and intellectual property rights were reviewed. As for the research method, participatory observation methods such as in-depth interviews with developers and operators and participation in meetings were conducted. The researcher participated in and observed the entire development process, including designing and developing blockchain nodes, smart contracts, APIs, UI/UX, and testing interworking between blockchain and content distribution services. Research Question 1: The results of the study on 'Which technology model is suitable for a blockchain-based performance video content distribution public platform?' are as follows. 1) The blockchain type suitable for the public platform for distribution of art performance video contents based on the blockchain is the private type that can be intervened only when the blockchain manager directly invites it. 2) In public platforms such as Gyeonggi ArtOn, among the copyright management model, which is an art based on NFT issuance, and the BC token and cloud-based content distribution model, the model that provides content to external demand organizations through API and uses K-token for fee settlement is suitable. 3) For public platform initial services such as Gyeonggi ArtOn, a closed blockchain that provides services only to users who have been granted the right to use content is suitable. Research question 2: What legal and institutional problems should be reviewed when operating a blockchain-based performance video distribution public platform? The results of the study are as follows. 1) Blockchain-based smart contracts have a party eligibility problem due to the nature of blockchain technology in which the identities of transaction parties may not be revealed. 2) When a security incident occurs in the block chain, it is difficult to recover the loss because it is unclear how to compensate or remedy the user's loss. 3) The concept of default cannot be applied to smart contracts, and even if the obligations under the smart contract have already been fulfilled, the possibility of incomplete performance must be reviewed.