• Title/Summary/Keyword: pre-exposure

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Extraction Process of Lead and Variations of Physicochemical Properties using the Smelting Experiment of Galena (방연석 제련실험을 통한 납 추출과정 및 물리화학적 거동변화 연구)

  • Han, Woo-Rim;Kim, So-Jin;Lee, Eun-Woo;Hwang, Jin-Ju;Kim, Su-Ki;Han, Min-Su
    • Journal of Conservation Science
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    • v.29 no.1
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    • pp.69-79
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    • 2013
  • This study aims at identifying the variation of physicochemical properties for galena ore in order to use it in understanding of manufacturing techniques in terms of metallurgical method and smelting or refining process for obtaining lead. The ores in the study obtained from the operating mine have been washed and pre-treated for a test. Metallic lead has been extracted by roasting process. The result displays that galena is still in present in the matt despite of exposure to high temperature, over $1000^{\circ}C$. Nearly $11.1g/cm^3$ specific gravity metallic lead has been collected from the refining test of which aim was to remove the remnant galena and a trace of concentrated silver has been identified at the grain boundary. The result suggests that at least one refining process was essential to acquire high purity metallic lead and cupellation had been executed to remove remnant silver.

Growth Inhibition Effects of Ethanol and Sodium Chloride on Bacillus cereus (Ethanol과 NaCl에 의한 Bacillus cereus 생육저해 영향)

  • Jang, Ji-Hyun;Jang, Jung-Soon;Lee, Sang-Yun;Kim, Hyun-Su;Kang, Sang-Mo;Park, Jong-Hyun
    • Korean Journal of Food Science and Technology
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    • v.35 no.5
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    • pp.998-1002
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    • 2003
  • Agricultural foodstuffs, usually consumed without sterilization, are frequently contaminated with foodborne pathogen B. cereus. Ethanol and sodium chloride were used to inhibit this pathogen for its effective control. Though five minutes of exposure to 20% ethanol did not inhibit the growth of B. cereus, inhibition was detected to 30% ethanol solution. As exposed longer, B. cereus was more effectively inhibited than E. coli and S. typhimurium. B. cereus, E. coli and S. typhimurium were not inhibited when exposed in a 10% sodium chloride solution for five minutes. However, these bacteria were inhibited with a combination of 10% sodium chloride and 20% ethanol solution for five minutes. Much synergistic growth inhibition on B. cereus was found at the treatment. Its viable count was reduced from $10^8cfu/ml$ to $10^2cfu/ml$ after five minutes and showed no count after ten minutes. This trend was also confirmed for the wild types of B. cereus. This method may be applied for the effective pre-treatment of many agricultural foodstuffs, especially uncooked foodstuffs, without the hazards that accompany special sanitizers and the nutritional loss from harsh sterilization.

Evaluation of Phototoxicity for Cosmetics and Alternative Method (화장품 광독성 평가와 동물대체시험법)

  • Lee, Jong-Kwon;Sin, Ji-Soon;Kim, Jin-Ho;Eom, Jun-Ho;Kim, Hyung-Soo;Park, Kui-Lea
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.31 no.3 s.52
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    • pp.245-251
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    • 2005
  • Safety is one of the key issue in the regulation of cosmetics. Cosmetic Act deals with it in Korea. The guidance for the testing cosmetic ingredients and their safety evaluation are prepared by Korea Food and Drug Administration. Ultraviolet radiation could Induce skin damage, edema, erythema, photoaging, immune dysfunction and skin cancer. Ultraviolet radiation is classified as Group 2A(probably carcinogenic to humans) by International Agenry for Reaserch on Cancer(IARC). The in vitro methodologies for evaluating the toxic potential of ingredients reported in the literature have not yet been sufficiently validated for use in areas other than the study for mutagenicity/genotoxicity, for pre-screening for severe irritancy, for screening of phototoxicity and for evaluating the percutaneous absorption. The 3T3 neutral red uptake photoxicity test (3T3 NRU PT) was accepted as OECD toxicity guideline in 2002. The 3T3 NRU PT is an in vitro method based on a comparison of the cytotoxicitv of a chemical when tested in the presence and in the absence of exposure to a non-cytotoxic dose of UVA/visible light.

CHEMICAL DEGRADATION OF LIGHT CURED COMPOSITE RESINS IN NAOH SOLUTION (NaOH 용액내에서의 광중합형 복합레진의 화학적 분해)

  • Kim, Jung-Ran;Jeong, Byung-Cho;Yang, Kyu-Ho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.29 no.3
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    • pp.469-477
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    • 2002
  • One of the major deficiencies of composite restorative resins is their insufficient resistance to wear. Of the multitude of factors that have been associated with wear, subsurface degradation within the restoration is considered to be one. The aim of this study was to evaluate the resistance to degradation of four commercial composite resins in an alkaline solution. The brands studied were Z100(3M), Clearfil AP-X(Kuraray), Tetric Ceram(Vivadent), Aelit flo(Bisco). Resistance to degradation was evaluated on the basis of the following parameters: (a) mass loss(%) - determined from pre-and post-exposure specimen weights: (b) Si loss(ppm) - obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth(${\mu}m$) - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were as follows: 1. The sequence of the mass loss was in ascending order by AE, EL, TC, Z100. There was statistically significant difference of mass loss between AE, CL group and TC, Z100 group(p<0.05). 2. The sequence of the degree of degradation layer depth was in ascending order by AE, CL, TC, Z100. But there was no statistically significant difference of degree of degradation layer depth between AE and CL(p<0.05). 3. For the Si concentration, Z100 was the highest of all. 4. The correlation coefficient between mass loss and degradation depth was relatively high(r=0.71 p<0.05).

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Protective Effect of Cosmetics Containing Red Beet against Cigarette Smoke-induced Oxidative Damage in Human Skin (레드비트를 함유하는 화장품의 담배 연기에 의한 피부 지질 산화 방지 효과)

  • Seo, Cho Rong;Ha, Tae Hyun;Moon, Ji Young;Kim, Jeong Mi;Park, Byoung Kwon;Lee, Ji Won;Park, Jin Oh;Shin, Jin Hee
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.44 no.2
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    • pp.111-116
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    • 2018
  • In cosmetics market, anti-pollution products recently come up with new solution for skin health. Environmental oxidation mechanisms are realized as bio-marker of atmospheric pollution upon skin by environmental pollutant such as ozone, UV rays, particulate matter (PM) as well as cigarette smoke. The exposure of cigarette smoke directly or indirectly causes the oxidation of the stratum corneum skin lipids, resulting in the conversion of squalene to squalene monohydroperoxide and/or generation of malondialdehyde (MDA) as a product of lipid peroxidation. The aim of this study is to see whether new cosmetics product containing red beet has anti-oxidation effect on skin exposed by cigarette smoke. So as to determine oxidative damage to human skin at biochemical level, each unit area of volar forearms was exposed to cigarette smoke through device (3.3 cm, diameter) for fifteen minutes, then measured MDA using standardized TBARS assay kit. Compared to negative control (untreated and unexposed area), the level of MDA was significantly increased at positive control (untreated and exposed area) more than 3.7 times, indicating the pollutant induced-oxidative damage on the skin barrier. Whereas, the pre-applied area with the cosmetics products containing red beet revealed a decrease of 25% compared with positive control. As reports, these data demonstrated that cigarette smoke induce peroxidation of stratum corneum skin lipids. Conclusively, we suggest that anti-pollution effect of the cosmetics product containing red beet is beneficial to prevent the oxidation of skin lipids by atmospheric pollution.

A Key Management Scheme for Ad hoc Sensor Networks (애드 혹 센서 네트워크를 위한 키 관리 방안)

  • Kim Seung-Hae;Chung Byung-Ho;Wang Gi-Cheol;Cho Gi-Hwan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.7 s.349
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    • pp.32-40
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    • 2006
  • It is very important to establish a pairwise key securely in wireless sensor networks. Because sensor networks consist of devices with weak physical security, they are likely to be compromised by an attacker. However, some approaches using key pre-distribution and other approaches using one hop local keys are known to be very vulnerable to threats caused by compromised nodes, even a small number. This paper proposes a scheme where each node establishes three hop local keys and employs them for a later pairwise key establishment. When any two nodes agree a pairwise key, all nodes on the route between two nodes contribute to the agreement of the pairwise key. Here, the initial three hop local keys are employed for encrypting a secret key delivered from a node to other nodes. Therefore, the proposed scheme bothers attackers to compromise much more nodes than the scheme using one hop local keys only. The simulation results have proven that the proposed scheme provides better performance and higher security than the scheme using one hop local keys in terms of message exchange, the number of encryption and decryption, and pairwise key exposure rate.

Characteristic of Ru Thin Film Deposited by ALD

  • Park, Jingyu;Jeon, Heeyoung;Kim, Hyunjung;Kim, Jinho;Jeon, Hyeongtag
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.78-78
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    • 2013
  • Recently, many platinoid metals like platinum and ruthenium have been used as an electrode of microelectronic devices because of their low resistivity and high work-function. However the material cost of Ru is very expensive and it usually takes long initial nucleation time on SiO2 during chemical deposition. Therefore many researchers have focused on how to enhance the initial growth rate on SiO2 surface. There are two methods to deposit Ru film with atomic layer deposition (ALD); the one is thermal ALD using dilute oxygen gas as a reactant, and the other is plasma enhanced ALD (PEALD) using NH3 plasma as a reactant. Generally, the film roughness of Ru film deposited by PEALD is smoother than that deposited by thermal ALD. However, the plasma is not favorable in the application of high aspect ratio structure. In this study, we used a bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a metal organic precursor for both thermal and plasma enhanced ALDs. In order to reduce initial nucleation time, we use several methods such as Ar plasma pre-treatment for PEALD and usage of sacrificial RuO2 under layer for thermal ALD. In case of PEALD, some of surface hydroxyls were removed from SiO2 substrate during the Ar plasma treatment. And relatively high surface nitrogen concentration after first NH3 plasma exposure step in ALD process was observed with in-situ Auger electron spectroscopy (AES). This means that surface amine filled the hydroxyl removed sites by the NH3 plasma. Surface amine played a role as a reduction site but not a nucleation site. Therefore, the precursor reduction was enhanced but the adhesion property was degraded. In case of thermal ALD, a Ru film was deposited from Ru precursors on the surface of RuO2 and the RuO2 film was reduced from RuO2/SiO2 interface to Ru during the deposition. The reduction process was controlled by oxygen partial pressure in ambient. Under high oxygen partial pressure, RuO2 was deposited on RuO2/SiO2, and under medium oxygen partial pressure, RuO2 was partially reduced and oxygen concentration in RuO2 film was decreased. Under low oxygen partial pressure, finally RuO2 was disappeared and about 3% of oxygen was remained. Usually rough surface was observed with longer initial nucleation time. However, the Ru deposited with reduction of RuO2 exhibits smooth surface and was deposited quickly because the sacrificial RuO2 has no initial nucleation time on SiO2 and played a role as a buffer layer between Ru and SiO2.

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Low-Tube-Voltage CT Urography Using Low-Concentration-Iodine Contrast Media and Iterative Reconstruction: A Multi-Institutional Randomized Controlled Trial for Comparison with Conventional CT Urography

  • Kim, Sang Youn;Cho, Jeong Yeon;Lee, Joongyub;Hwang, Sung Il;Moon, Min Hoan;Lee, Eun Ju;Hong, Seong Sook;Kim, Chan Kyo;Kim, Kyeong Ah;Park, Sung Bin;Sung, Deuk Jae;Kim, Yongsoo;Kim, You Me;Jung, Sung Il;Rha, Sung Eun;Kim, Dong Won;Lee, Hyun;Shim, Youngsup;Hwang, Inpyeong;Woo, Sungmin;Choi, Hyuck Jae
    • Korean Journal of Radiology
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    • v.19 no.6
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    • pp.1119-1129
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    • 2018
  • Objective: To compare the image quality of low-tube-voltage and low-iodine-concentration-contrast-medium (LVLC) computed tomography urography (CTU) with iterative reconstruction (IR) with that of conventional CTU. Materials and Methods: This prospective, multi-institutional, randomized controlled trial was performed at 16 hospitals using CT scanners from various vendors. Patients were randomly assigned to the following groups: 1) the LVLC-CTU (80 kVp and 240 mgI/mL) with IR group and 2) the conventional CTU (120 kVp and 350 mgI/mL) with filtered-back projection group. The overall diagnostic acceptability, sharpness, and noise were assessed. Additionally, the mean attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM) in the urinary tract were evaluated. Results: The study included 299 patients (LVLC-CTU group: 150 patients; conventional CTU group: 149 patients). The LVLC-CTU group had a significantly lower effective radiation dose ($5.73{\pm}4.04$ vs. $8.43{\pm}4.38mSv$) compared to the conventional CTU group. LVLC-CTU showed at least standard diagnostic acceptability (score ${\geq}3$), but it was non-inferior when compared to conventional CTU. The mean attenuation value, mean SNR, CNR, and FOM in all pre-defined segments of the urinary tract were significantly higher in the LVLC-CTU group than in the conventional CTU group. Conclusion: The diagnostic acceptability and quantitative image quality of LVLC-CTU with IR are not inferior to those of conventional CTU. Additionally, LVLC-CTU with IR is beneficial because both radiation exposure and total iodine load are reduced.

Development of Multi-Camera based Mobile Mapping System for HD Map Production (정밀지도 구축을 위한 다중카메라기반 모바일매핑시스템 개발)

  • Hong, Ju Seok;Shin, Jin Soo;Shin, Dae Man
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.39 no.6
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    • pp.587-598
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    • 2021
  • This study aims to develop a multi-camera based MMS (Mobile Mapping System) technology for building a HD (High Definition) map for autonomous driving and for quick update. To replace expensive lidar sensors and reduce long processing times, we intend to develop a low-cost and efficient MMS by applying multiple cameras and real-time data pre-processing. To this end, multi-camera storage technology development, multi-camera time synchronization technology development, and MMS prototype development were performed. We developed a storage module for real-time JPG compression of high-speed images acquired from multiple cameras, and developed an event signal and GNSS (Global Navigation Satellite System) time server-based synchronization method to record the exposure time multiple images taken in real time. And based on the requirements of each sector, MMS was designed and prototypes were produced. Finally, to verify the performance of the manufactured multi-camera-based MMS, data were acquired from an actual 1,000 km road and quantitative evaluation was performed. As a result of the evaluation, the time synchronization performance was less than 1/1000 second, and the position accuracy of the point cloud obtained through SFM (Structure from Motion) image processing was around 5 cm. Through the evaluation results, it was found that the multi-camera based MMS technology developed in this study showed the performance that satisfies the criteria for building a HD map.

Effects of Exposure to Cooking Show Contents on the Consumption of Agricultural Products: Focused on Potato Consumption (쿡방 콘텐츠 노출이 농식품 소비에 미치는 효과: 감자 소비를 중심으로)

  • Rah, HyungChul;Kim, Hyeon-Woong;Ko, Hyeonseok;Shin, Jaehoon;Cho, Yongbeen;Nasridinov, Aziz;Yoo, Kwan-Hee
    • The Journal of the Korea Contents Association
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    • v.21 no.12
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    • pp.400-407
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    • 2021
  • Recently, mukbang and cookbang or cooking shows on TV and YouTube channels have increased, and the influences of these broadcasts on food consumption have been gradually increasing. There were several news articles on 'Baek Jong-won effect', in which the consumption of the agri-food Mr. Jong-won Baek mentioned on his broadcast soared, and even foods named after him are on the market. In this study, Mr. Jong-won Baek, who produces influential cooking contents through various media, was taken as a representative example. We evaluated if 'Baek Jong-won effect' exists on potato consumption, which Mr. Jong-won Baek broadcasted potato cooking recipes on TV and YouTube. After the potato recipe was broadcasted for the first time on the TV show called HomeFoodRescue, the differences in the amount of money to purchase potatoes before and after the broadcast were estimated by using the money amount to purchase data of Agri-food consumers panel and the difference-in-differences method at 6 time points (3, 6, 9, 12, 24, and 36 months). Among the time points analyzed, the potato purchases at post-broadcast were less than those at pre-broadcast. No results were observed suggesting the existence of 'Baek Jong-won effect' on potato consumption through HomeFoodRescue show in the study.