• 한국자동차공학회논문집
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• 제16권1호
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• pp.8-13
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• 2008

Emissions from automobiles have long been considered a prime source of pollutants involved in smog formation and ozone production. Especially VOCs are associated with serious environmental problems such as photo-chemical smog as well as human health effects. Since motor vehicles are a major source of VOCs, estimating of emission from mobile source is the most important factor to control VOCs. VOCs are emitted from various pollution like motor vehicles, mobile and stationary source that has characteristics of toxicity, cancer-causing, bio-accumulation, durability in air and diffusion can exert a bad influence upon human health and environment. However we don't have any standard or regulation about VOCs emissions. This study is summarized as VOCs emission characteristics from in-use light-duty diesel and LPG fueled vehicles. The vehicle exhaust-gas test mode is CVS cycle and nier-10 cycles that developed on EPA and National Institute of Environmental Research. TO-14 method (Toxic Organic) was chosen for VOCs analysis from EPA in USA. This study results will be useful when make a emission factor and rule making of emission standard about domestic VOCs emission for the improve to air condition.

• Food Science and Biotechnology
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• 제14권2호
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• pp.200-206
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• 2005

Effect of quercetin on NO production and regulation mode of quercetin on oxidative stress, $NF{\kappa}B$ activation, and iNOS expression, possible mechanisms of NO suppression in LPS-stimulated macrophages were investigated. Treatment of RAW 264.7 cells with quercetin significantly reduced lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production dose-dependently ($IC_{50}$, $9.2\;{\mu}M$). Expression of iNOS and specific DNA binding activities of nuclear factor kB ($NF{\kappa}B$) were significantly suppressed by quercetin pretreatment. Quercetin reduced thiobarbituric acid-reactive substances (TBARS) accumulation, enhancing GSH level and antioxidant activities of enzymes, such as superoxide dismutase (SOD) and catalase. These results demonstrate quercetin may ameliorate inflammatory diseases by suppressing NO production through inhibition of iNOS expression, $NF{\kappa}B$ transactivation, and oxidative stress, which may be mediated partially by antioxidative effect of quercetin. Thus, quercetin appears to be used as a potential therapeutic agent for treating LPS-induced inflammatory processes.

• 한국환경보건학회지
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• 제35권4호
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• pp.334-342
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• 2009

Perfluorinated compounds (PFCs) have a wide range of domestic and industrial applications, but they are persistent in the environment. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) are among the metabolites of PFCs and occur at high concentration in the environment. Korea is the largest importer of PFC compounds in the world, therefore, the accumulation of these compounds is possible. In this study, the concentrations of PFOS and PFOA were determined in water samples taken from sewage treatment plants (STPs) and the Han River in Seoul, Korea. After extraction with a HLB cartridge, PFCs in the samples were analyzed by HPLC with an ion trap mass spectrometry in electrospray negative mode. Limits of detection was between 1 and 1.6 ng/l. The result showed that the concentrations of PFOS and PFOA in effluent and influent of the four STPs in Seoul were 60~570 ng/l, and not detected (nd)~254 ng/l, respectively. The levels of PFOS and PFOA were higher in the effluents which passed through the treatment process than in influent water samples which was against expectation. The concentration of PFOA and PFOS in the Han River was 60~570 ng/l and nd~254 ng/l, respectively. PFOA was detected in every sample, but PFOS was only detected in the downstreams of the Han River. This result indicates that there is comprehensive contamination of PFCs in the aquatic environment in Korea.

• Environmental Engineering Research
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• 제24권4호
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• pp.690-698
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• 2019

Air pollution has attracted ever-increasing attention because of its substantial influence on air quality and human health. To better understand the characteristics of long-range transported pollution, the single particle chemical composition and size were investigated by the single particle aerosol mass spectrometry in Fuzhou, China from 17th to 22nd January, 2016. The results showed that the haze was mainly caused by the transport of cold air mass under higher wind speed (10 m·s^-1) from the Yangtze River Delta region to Fuzhou. The number concentration elevated from 1,000 to 4,500 #·h^-1, and the composition of mobile source and secondary aerosol increased from 24.3% to 30.9% and from 16.0% to 22.5%, respectively. Then, the haze was eliminated by the clean air mass from the sea as indicated by a sharp decrease of particle number concentration from 4,500 to 1,000 #·h^-1. The composition of secondary aerosol and mobile sources decreased from 29.3% to 23.5% and from 30.9% to 23.1%, respectively. The particles with the size ranging from 0.5 to 1.5 ㎛ were mainly in the accumulation mode. The stationary source, mobile source, and secondary aerosol contributed to over 70% of the potential sources. These results will help to understand the physical and chemical characteristics of long- range transported pollutants.

• 대한조선학회지
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• 제13권1호
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• pp.1-9
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• 1976

Using the computer programs for calculation of natural vibrations of ship's hull developed by the authors et al., an investigation into influences of various parameters on the accuracy of calculation was done through example calculations of a 30,000 DWT petroleum products carrier M/S Sweet Brier built by Korea Shipbuilding and Engineering Corporation. The methodical principles employed for the computer program development are as follows; (a) the ship system is reduced to an equivalent discrete elements system conforming to Myklestad-Prohl model, (b) the problem formulation is of transfer matrix method, and (c) to obtain solutions an extended $G\ddot{u}mbel's$ initial value method is introduced. The scope of the investigation is influences of number of discrete elements, choice of significant system parameters such as rotary inertia, bending stiffness and shear stiffness, and simplification of distributions of added mass and stiffness as trapezoidal ones referred to those of midship section on the calculation accuracy. From the investigation the followings are found out; (1) To obtain good results for the modes up to the seven-noded thirty or more divisions of the hull is desirable. For fundamental mode fifteen divisions may give fairly good results. (2) The influence of rotary inertia is negligibly small at least for the modes up to the 5- or 6- noded. (3) In the case of assuming either bending modes or shear modes the calculation results in considerably higher frequencies as compared with those based on Timoshenko beam theory. However, the calculation base on the slender beam theory surprisingly gives frequencies within 10% error for fundamental modes. (4) It is proved that to simplify distributions of added mass and stiffness as trapezoidal ones referred to those of midship section is a promising approach for the prediction of natural frequencies at preliminary design stage; provided good accumulation of data from similar type ships, we may expect to obtain natural frequencies within 5% error.

• The Korean Journal of Physiology and Pharmacology
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• 제12권5호
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• pp.267-274
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• 2008

Since first discovered in chick skeletal muscles, stretch-activated channels (SACs) have been proposed as a probable mechano-transducer of the mechanical stimulus at the cellular level. Channel properties have been studied in both the single-channel and the whole-cell level. There is growing evidence to indicate that major stretch-induced changes in electrical activity are mediated by activation of these channels. We aimed to investigate the mechanism of stretch-induced automaticity by exploiting a recent mathematical model of rat atrial myocytes which had been established to reproduce cellular activities such as the action potential, $Ca^{2+}$ transients, and contractile force. The incorporation of SACs into the mathematical model, based on experimental results, successfully reproduced the repetitive firing of spontaneous action potentials by stretch. The induced automaticity was composed of two phases. The early phase was driven by increased background conductance of voltage-gated $Na^+$ channel, whereas the later phase was driven by the reverse-mode operation of $Na^+/Ca^{2+}$ exchange current secondary to the accumulation of $Na^+$ and $Ca^{2+}$ through SACs. These results of simulation successfully demonstrate how the SACs can induce automaticity in a single atrial myocyte which may act as a focus to initiate and maintain atrial fibrillation in concert with other arrhythmogenic changes in the heart.

• 한국가스학회지
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• 제7권2호
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• pp.48-53
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• 2003

에너지 관련 플랜트에 사용되는 배관은 플랜트의 성능이나 안전성유지에 있어서 중요한 설비의 일부이다. 본 연구에서는 고압탄소강 배관의 변형 및 파괴에 대한 음향방출 기초 자료를 얻기 위하여 압력용기용 배관재를 기계가공하여 인장시험편을 만든 후, 인장시험을 실시하여 항복, 소성변형 및 파괴에 이르기까지의 음향방출 신호를 분석하였다. 탄성영역, 최대인장강도 이전의 소성영역 및 최대인장강도 이후의 소성영역에서 검출된 음향방출의 시간-주파수 분석 결과는 탄성영역에서 항복영역까지는 비교적 낮은 저주파수 대역(250${\~}$350kHz)이 나타났으며, 소성영역에서는 저주파수뿐만 아니라 고주파수 대역(500kHz)도 나타났다. 인장시험 후, 이러한 각 영역의 구별이 가능하였던 원인은 항복영역에서의 전위의 이동, 집적에 따른 신호와 최대인장강도 이전의 소성영역에서의 전위들이 개재물이나 결정입계를 통과했을 때 나타나는 신호, 최대인장강도 이후에는 미소공동의 발생, 성장 및 합체에 의하여 나타나는 신호로 분류가 가능하였기 때문인 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.631-634
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• 2004

The method that exists in Photodynamic Therapy uses Photosensibility drug strongly Influencing tumour accumulation together with photochemical laser effect and makes the structure of tumour be localized and become extinct. The intracavity transformation of the Nd :YAP main radiation 1079 nm was Raman converted in barium nitrate crystal and the Stokes frequency (1216 nm) was doubled using KTP or RTA crystals. The LiF or Cr:YAG crystals are used for the Q-switch. The radiation Parameters were obtained at 100 Hz pump repetition frequency. The average power at 608 nm radiation with LiF and KTP was 700 mW at multi-mode generation. The 3-6 single 10-15 ns pulses were generated during one cycle of pumping. The doubling efficiency with RTA was two times more than with KTP. The cells of Ehrlich adenocarcinoma (0.1 ml) were i.m. implanted in hind thighs of ICR white non-imbred mice. The cells were preliminarily diluted in medium 199 in the ratio of 1 to 5. HpD was intravenous administered in a dose of 10 mg/kg. The left clean-shaven hind leg was irradiated with laser light 21-27 hours after the administration of the preparation. The right non-Irradiated leg of each animal served as a control. The animals with the transplanted tumor that were not injected with HpD sewed as a control to estimate the complex effect (HpD+ irradiation). Before the administration of HpD and on 3 and 4 days after irradiation the tumor size was measured and the percent of the tumor growth inhibition was calculated. The results of animal treatments has shown high efficiency of PDT method for cancer treatment by means 0.608 m high power pulse solid state laser.

• 대기
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• 제28권4호
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• pp.469-477
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• 2018

We performed the comparison of observed $PM_{10}$ and $PM_{2.5}$ at both the Yonsei University and the AIRKOREA site in the same Seodaemun-gu district, Seoul from March to December 2016. Generally, the moderate correlations between two sites were found for both $PM_{10}$ and $PM_{2.5}$, but monthly difference was somewhat occurred, implying that the measurement situation is not equally maintained even in a closely located area. Particularly correlations became weaker in June and July, which seems the impact of rainy conditions. Correlations between two stations were higher for $PM_{10}$ compared to $PM_{2.5}$, probably indicating the spatially larger difference of fine mode particle. Monthly mean variation was similar between two sites showing a maximum in March and minimum in August. Diurnal variation was somewhat different: morning peak at Yonsei University but evening peak at the Seodaemun-gu AIRKOREA site, reflecting the difference of local air condition. We also compared the extent of $PM_{10}$ and $PM_{2.5}$ according to the local wind speed and direction. In general, the level of particulate matter was high when the wind is blowing from the northwestern area with low wind speed, meaning the high accumulation effect of transported air particles. Findings of this study can be usefully considered for the investigation about the discrepancy of aerosol measurement in a local scale.

• Journal of Radiation Protection and Research
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• 제47권3호
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• pp.134-142
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• 2022

Background: This study investigated the characteristics of optically stimulated luminescence dosimeters (OSLDs) with fully filled deep electron/hole traps in the kV energy ranges. Materials and Methods: The experimental group consisted of InLight nanoDots, whose deep electron/hole traps were fully filled with 5 kGy pre-irradiation (OSLD_exp), whereas the non-pre-irradiated OSLDs were arranged as a control group (OSLD_cont). Absorbed doses for 75, 80, 85, 90, 95, 100, and 105 kVp with 200 mA and 40 ms were measured and defined as the unit doses for each energy value. A bleaching device equipped with a 520-nm long-pass filter was used, and the strong beam mode was used to read out signal counts. The characteristics were investigated in terms of fading, dose sensitivities according to the accumulated doses, and dose linearity. Results and Discussion: In OSLD_exp, the average normalized counts (sensitivities) were 12.7%, 14.0%, 15.0%, 10.2%, 18.0%, 17.9%, and 17.3% higher compared with those in OSLD_cont for 75, 80, 90, 95, 100, and 105 kVp, respectively. The dose accumulation and bleaching time did not significantly alter the sensitivity, regardless of the filling of deep traps for all radiation qualities. Both OSLD_exp and OSLD_cont exhibited good linearity, by showing coefficients determination (R²) > 0.99. The OSL sensitivities can be increased by filling of deep electron/hole traps in the energy ranges between 75 and 105 kVp, and they exhibited no significant variations according to the bleaching time.