• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.204-212
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• 2008

The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Guttapercha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

• Journal of Radiation Protection and Research
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• v.37 no.1
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• pp.10-15
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• 2012

Design and performance test results of a newly developed optically stimulated luminescence (OSL) measurement system are presented in this paper. Generally, different types of optical filters are used in OSL reader system to minimize the interference of the stimulation light in the OSL signal. For optically stimulation of $Al_2O_3:C$, we have arrived at an optimal combination of the filters, i.e., GG420 filter for filtering the stimulating light source, and a combined UG11 and BG39 filter at the detecting window (PMT). By using a high luminance blue LED (Luxeon V), sufficient luminous intensity could be obtained for optically stimulation. By using various control boards, the OSL reader device was successfully interfaced with a personal computer. A software was developed to deliver required commands to operate the OSL reader by using the LabView program (National Instruments, Inc.). In order to evaluate the reliability and the reproducibility of newly designed-OSL reader. Performance testing of the OSL reader was carried out for OSL efficiency, OSL decay curve and signal to noise ratio of the standard $Al_2O_3:C$ OSL material. It was found to be comparable with that of commercial Riso reader system.

• Proceedings of the KACD Conference
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• 2008.05a
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• pp.204-212
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• 2008

The purpose of this study was to compare the apical microleakage in root canal filled with Resilon by methacrylate-based root canal sealer or 2 different self-adhesive resin cements. Seventy single-rooted extracted human teeth were sectioned at the CEJ perpendicular to the long axis of the roots with diamond disk. Canal preparation was performed with crown-down technique using Profile NiTi rotary instruments and GG drill. Each canal was prepared to ISO size 40, .04 taper and 1 mm short from the apex. The prepared roots were randomly divided into 4 experimental groups of 15 roots each and 5 roots each for positive and negative control group. The root canals were filled by lateral condensation as follows. Group 1: Gutta-percha with AH-26, Group 2: Resilon with RealSeal primer & sealer, Group 3: Resilon with Rely-X Unicem, Group 4: Resilon with BisCem. After stored in $37^{\circ}C$, 100% humidity chamber for 7 days, the roots were coated with 2 layers of nail varnish except apical 3 mm. The roots were then immersed in 1% methylene blue dye for 7 days. Apical microleakage was measured by a maximum length of linear dye penetration after roots were separated longitudinally. One way ANOVA and Scheffe's post-hoc test were performed for statistical analysis. Group 1 showed the least apical leakage and there was no statistical significance between Group 2, 3, 4. According to the results, the self adhesive resin cement is possible to use as sealer instead of primer & sealant when root canal filled by Resilon.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.484-490
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• 2009

The purpose of this study was to evaluate the effect of soft chelating irrigant on the sealing ability of root fillings by using a glucose leakage test. A total of 45 single-rooted teeth were selected for the study. The teeth were decoronated leaving a total length of 13mm. The root canals prepared using K3 NiTi rotary instruments to an apical dimension of size 45(0.06 taper). The specimens were then randomly divided into 3 experimental groups of 13 roots each and 2 control groups of 3 roots each. Specimen in each group were prepared with different irrigation protocols : group 1, 2.5% NaOCl; group 2, 2.5% NaOCl and 17% EDTA: group 3, 2.5% NaOCl and 15% HEBP. The root canals were filled with gutta-percha and AH Plus sealer using lateral condensation. After 7 days in $37^{\circ}C$, 100% humidity, the coronal-to-apical microleakage was evaluated quantitatively using a glucose leakage model. The leaked glucose concentration was measured with spectrophotometry at 1, 4, 7, 14, 21 and 28 days. There was a tendency of increase in leakage in all experimental groups during experimental period. HEBP-treated dentin showed no significant difference with EDTA-treated dentin during experimental period. From the 21th day onward, HEBP-treated dentin showed significantly lower leakage than smear-covered dentin. HEBP-treated dentin displayed a similar sealing pattern to EDTA-treated dentin and a better sealing ability than smear-covered dentin. Consequently, a soft chelator(HEBP) could be considered as the possible alternative to EDTA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.112-119
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• 2016

This study aims to examine propping by the controlling shareholders and the corporate value of Korean firms with agency problems and propping perspectives. Propping refers to a transfer of resources from a higher ownership firm to a lower ownership firm, in order to prevent the latter from going bankrupt. This study used a sample of 4,077 companies listed on the KRX data exchange from 2004 to 2014. We used proxy variables such as long-term supply contracts, asset and business sales, credit facilities, loans, and equity investments to affiliates as wealth transfer instruments of the controlling shareholders. We found that propping occurred by the equity investment of affiliates in Korean firms. Also, we found that the Korean firm's value was decreased by the affiliate equity investment.

• Analytical Science and Technology
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• v.31 no.1
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• pp.31-38
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• 2018

The energy recovery rate estimation method proposed through the Waste Control Act does not take into account the energy used in practice. In addition, the method for measuring a lower heating value, which is the main factor of the energy recovery rate, was carried out through a small sampling amount, and thus the representative value of the waste was not reflected. With the revised estimation method (Notification No. 2015-215 of the Ministry of Environment), the energy recovery rate should be estimated based on the actual amount of energy used, and a heat balance method was proposed as a way to estimate the lower heating value. In this study, the lower heating value was estimated for seven industrial waste incineration facilities according to the revised estimation method. All data used in the estimations were achieved from measurement instruments applied to each of the incinerators and through direct measurements taken by the operators for the purposes of calculation. As a result, the lower heating value was estimated to be about 3,404.7 kcal/kg for the seven industrial waste incineration facilities.

• The KIPS Transactions:PartA
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• v.18A no.1
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• pp.1-10
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• 2011

Physical modeling has been widely used for sound synthesis since it synthesizes high quality sound which is similar to real-sound for musical instruments. However, physical modeling requires a lot of parameters to synthesize a large number of sounds simultaneously for the musical instrument, preventing its real-time processing. To solve this problem, this paper proposes a single instruction, multiple data (SIMD) based multi-core processor that supports real-time processing of sound synthesis of gayageum which is a representative Korean traditional musical instrument. The proposed SIMD-base multi-core processor consists of 12 processing elements (PE) to control 12 strings of gayageum in which each PE supports modeling of the corresponding string. The proposed SIMD-based multi-core processor can generate synthesized sounds of 12 strings simultaneously after receiving excitation signals and parameters of each string as an input. Experimental results using a sampling reate 44.1 kHz and 16 bits quantization show that synthesis sound using the proposed multi-core processor was very similar to the original sound. In addition, the proposed multi-core processor outperforms commercial processors(TI's TMS320C6416, ARM926EJ-S, ARM1020E) in terms of execution time ($5.6{\sim}11.4{\times}$ better) and energy efficiency (about $553{\sim}1,424{\times}$ better).

• The Journal of the Acoustical Society of Korea
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• v.29 no.3
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• pp.191-199
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• 2010

Physical modeling is a synthesis method of high quality sound which is similar to real sound for musical instruments. However, since physical modeling requires a lot of parameters to synthesize sound of a musical instrument, it prevents real-time processing for the musical instrument which supports a large number of sounds simultaneously. To solve this problem, this paper proposes a single instruction multiple data (SIMD) parallel processor that supports real-time processing of sound synthesis of guitar, a representative plucked string musical instrument. To control six strings of guitar, we used a SIMD parallel processor which consists of six processing elements (PEs). Each PE supports modeling of the corresponding string. The proposed SIMD processor can generate synthesized sounds of six strings simultaneously when a parallel synthesis algorithm receives excitation signals and parameters of each string as an input. Experimental results using a sampling rate 44.1 kHz and 16 bits quantization indicate that synthesis sounds using the proposed parallel processor were very similar to original sound. In addition, the proposed parallel processor outperforms commercial TI's TMS320C6416 in terms of execution time (8.9x better) and energy efficiency (39.8x better).

• Food Science and Preservation
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• v.20 no.6
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• pp.871-876
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• 2013

The purpose of this study was to investigate antimicrobial effectiveness of Omija (Schizandra chinensis Baillon) treated with $ClO_2$ (chlorine dioxide) concentration (10, 15, 20, 25 and 30 ppm), washing time (30, 60 and 90 sec) and multiple proportion (x1, x2, x3 and x4). The seven groups were divided into control (Omija without washing water treatment), W-T (Omija treated by tap water ($20{\pm}1^{\circ}C$) for 30 seconds), $ClO_2$-10 (Omija treated by 10 ppm $ClO_2$), $ClO_2$-15 (Omija treated by 15 ppm $ClO_2$), $ClO_2$-20 (Omija treated by 20 ppm $ClO_2$), $ClO_2$-25 (Omija treated by 25 ppm $ClO_2$), $ClO_2$-30 (Omija treated by 30 ppm $ClO_2$), and then they were detected number of total aerobic bacteria, yeast and mold. The rate of inactivation was found, for microorganisms of total aerobic bacteria, yeast and mold, to increase with a increase of $ClO_2$ treatment concentration and multiple proportion. No total aerobic bacteria, yeast and mold in $ClO_2$-30 sample treated for 30 sec, $ClO_2$-15 treated for 60 sec and $ClO_2$-10 treated for 90 sec were detected, and in $ClO_2$-30 Omija with multiple proportion ${\times}1$ (Omija : 30 ppm $ClO_2$ solution ratio was 1:1 (w/w)), $ClO_2$-20 with ${\times}2$ (Omija : 20 ppm $ClO_2$ solution ratio was 1:2 (w/w)) and $ClO_2$-15 with ${\times}4$ (Omija : 15 ppm $ClO_2$ solution ratio was 1:4 (w/w)) respectively.