• Food Science and Preservation
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• v.9 no.4
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• pp.369-374
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• 2002

This study was performed to investigate the effects of tyrosinase inhibition, xanthine oxidase inhibition and nitrite-scavenging effects of gamma-irradiated Schizandrae Fructus extracts from different solvents. Schizandrae Fructus was extracted by hot water, ethanol, acetone and methanol, and the extracts were irradiated 10, 20 and 30 kGy with gamma rays. All extracts from Schizandrae Fructus showed inhibition effect against tyrosinase. Tyrosinase inhibition effect of Schizandrae Fructus were higher in solvent extracts than hot water extracts by irradiation. The Schizandrae Fructus extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not changed by irradiation. Nitrite scavenging activity, which was measured at various pH conditions (1.2, 3.0, 6.0), was the highest in Schizandrae Fructus extracts at pH 1.2 and 3.0. Hot water extracts provided higher nitrite scavenging effect than those of the methanol, ethanol and acetone extracts. Gamma-Irradiation may not influence on biological activites of the extracts when irradiated up to 30 kGy.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.28.4-29
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• 2010

이 연구는 심우주 추적망(Deep Space Network) 측정 시스템의 구현을 위한 한국형 심우주 항법 예비 소프트웨어(Korean Deep Space Orbit Determination Program version 1; K-DSODP ver.1)의 개발을 목표로 한다. 연구의 주 내용은 심우주 항법을 위한 기초 기술 연구로 지구로부터 달까지 진행하는 탐사선의 궤적 추정에 대한 것이며, 연구의 시작에 앞서 사용될 관측 데이터를 얻기 위해 한국형 심우주 항법 관측데이터 생성 소프트웨어(Korean Deep Space Observation Data Generation Program version 1; K-DSODGP ver.1)를 개발하여 사용하였다. 임의의 잡음이 추가된 가상의 관측 데이터를 생성한 후, 이 관측 데이터를 실제 궤도로 상정하여 기하학적인 관측 모델을 수립하였고, 일정한 시간 간격동안 모은 임의의 관측 데이터를 가지고 궤도 결정을 수행하여 추정된 궤도를 전파하였다. 궤도 결정 알고리즘을 구성하기 위해 기본적인 좌표계, 탐사선에 미치는 지구의 중력에 대한 동역학 모델, 천체력과 탐사선의 동역학 모델로 구성된 관측 모델들을 유도하였으며, 탐사선의 위치와 속도를 추정하는 과정에서 가중치 최소 자승법을 적용하여 추정 궤도와 실제 궤도의 최소화를 유도하였다. 이러한 일련의 과정을 통해 요구한 시각의 탐사선의 위치와 속도를 결정하는 궤도결정 시스템을 구현하였고, 궤도 결정 시스템의 성능을 평가하기 위해 전파된 궤도와 실제 궤도의 차이를 분석하였다. 결과적으로 300초마다 관측데이터를 받을 경우, 2일 이상의 궤도결정 시간간격을 상정했을 때 평균 오차는 각각 약 0.26km RMS(range), 6.84km/s RMS(range-rate) 이내의 결과를 얻었고, 600초마다 관측데이터를 받을 경우, 평균 오차는 각각 약 0.30km RMS (range), 6.35km/s RMS(range-rate) 이내의 안정적인 결과를 얻었다. 이 연구의 결과를 통하여 추후 심화된 심우주 항법 소프트웨어 개발을 위한 기반이 마련될 것이다.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.1-8
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• 2008

The security of wireless sensor networks is a challenging research area where the resources constraints are a bottleneck for any successful security design. Due to their computational feasibility, symmetric key algorithms that require key pre-distribution are more desirable for use in these networks. In the pre-distribution scheme, keys or keying materials are assigned to each node prior deployment to guarantee a secure communication within the entire network. Though several works are introduced on this issue, yet the connectivity and resiliency are imperfectly handled. In this paper, we revisit the grid based key pre-distribution scheme aiming to improve the connectivity, introduce a higher resiliency level, simplify the logic of key establishment and maintain same level of used of resources usage. The core of our modification relies on introducing the novel plat-based polynomial assignment and key establishment mechanism. To demonstrate the advantageous properties of our scheme over the revisited one, details of consumed resources, resulting connectivity, security and comparisons with relevant works are introduced.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.4
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• pp.21-27
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• 2022

In this paper, the combustion characteristics of solid propellant embedded with metal wires were analyzed by the ground tests of motors. The propellant grains were made of thermoplastic propellants with Al and Cu as metal wires for the enhancement of burning area and designed with cone shape for better ignition. These metals were used to confirm the enhancement of burning rate on thermal diffusivity properties. The internal ballistics analysis and ground test were performed to investigate the effect of burning rate for each metal wire. We obtained the results of burning rate on a difference of thermal diffusivity of each metal wire with well-made propellant grains.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.59-64
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• 2010

Building a firebreak against surface forest fire is a typical indirect suppression method that stops spread of flame by removing surface fuel, such as fallen leaves and bushes. In the sense of fire dynamic, building a firebreak is to set a section which will block thermal energy from igniting on virgin fuel. This study suggests and evaluates a calculation method for width of firebreak against surface fire for variant wind and slope conditions by applying the Point Source Model (PSM) to fallen leaves of Pinus densiflora. Width of firebreak was measured based on the distance the threshold radiant heat igniting Pinus densiflora fallen leaves at the heat flux of $4.9\;kW/m^2$ reaches. As a result, at the wind velocity of 0~5 m/s and on the slope of $0{\sim}50^{\circ}$, the appropriate width of a firebreak was 0.35~0.65 m for the mean flame height and 0.75~1.05 m for the maximum flame height. Accordingly, considering the factor of safety, the most appropriate width of a firebreak is 1.05 m based on the maximum flame height. Additional comparative analyses through experiments and field surveys are deemed necessary to determine appropriate widths of firebreak for different types of surface fuel.

• Food Science and Preservation
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• v.16 no.2
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• pp.198-203
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• 2009

We examined the effects of electron-beam irradiation(0.5, 1, 2, or 5 kGy) on microbiological, physicochemical, and sensory quality characteristics of Myungran Jeotgal, Korean fermented seafood, during subsequent storage at $4^{\circ}C$ for 2 weeks. Viable counts of total aerobic bacteria, yeasts and molds, and total coliforms fell, after irradiation, to below detection limits($10^1CFU/g$). The pH of irradiated Myungran Jeotgal was maintained during storage but that of the non-irradiated control decreased. Sensory quality was not affected by electron-beam irradiation, except that color scores in samples irradiated with 2 and 5 kGy were lower than that of the control. Lipid oxidation tended to rise with increased irradiation dose and longer storage periods. The results suggest that electron-beam irradiation can be used to extend the shelf-life of Myungran Jeotgal without apparent quality attribute deterioration. However, means of preventing lipid oxidation resulting from electron-beam irradiation need consideration if irradiation is to find further applications in the food industry.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.31-37
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• 2018

In the surface contamination test using the end-window Geiger-Muller type counter, the wrap is used as a method for protecting the detector exposed to the outside in order to measure the beta-rays. We analyze the effect of this method on the measurement rate and the correction factor, and wanted to make it clear to radiation workers that excessive use of the wrap can affect the measured value of the beta-rays. The experimental method was to compare and analyze the change of the beta-rays measurement counting rate and the calibration factor according to the wrap thickness using the beta-rays with different energy of 3 KBq, 1.5 KBq and 0.3 KBq. The subjects of this study were the end-window Geiger-Muller type counter which were held at the calibration center certified by Korea Laboratory Accreditation Scheme (KOLAS) in March 2012, Cl-36 (Chlorine) and Sr-90 (Strontium) were used as the source of beta radiation. The measurement counting rate decreased with increasing wrap thickness, and the calibration factor increased with increasing wrap thickness. Since the changes of the measurement counting rate and the calibration factors can reduce the accuracy of the instrument readings, but also have a significant impact on detector contamination and damage, so there is a need to find out what thickness of wrap is most effective. If we using a wraps with thickness that show a low rate of change of the measurement counting rate and the calibration factor, it will protect the detector and minimize the effect on the measured value of the beta-rays.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.199-210
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• 2000

We present the results from narrow-band spectrophotometry of Comet Hale-Bopp (C/1995 O1) near perihelion obtained at Sobaeksan Optical Astronomy Observatory 61cm telescope equipped with PM 512 CCD camera(512$\times$512, 0.5"/pixel) and narrow-band filter set for the comet on 19 nights from February 21 to May 1, 1997. We discuss molecular emission band morphology and photometric behavior of Comet Hale-Bopp. The morphology of CN band shows more symmetric light distributions than $C_2$ or $C_3$ bands. On other hand, $C_2$ and $C_3$ band have more compact light distributions than CN band. Similar to wide-band image, molecular band morphology shows spiral structures at the core of the comet. The CN surface brightness variation with changing heliocentric distance shows difference from those of $C_2$ and $C_3$. The brightness, however, of these molecular bands near perihelion shows previously known 7day period light variations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.131-140
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• 1993

A new model which requires one branch of main curves for the model calibration is developed based on the assumption that the weighting factor accounting for the pore blockage effect against air entry, $P_a({\theta})$, in Mualem's Model III-1 has a linear relation to the dimensionless pore radius r. The proposed model simulates experimental data more accurately than existing models which require one branch of main curves for the model calibration. Previous study showed that Model III-1 is the most appropriate model among domain models which require two branches of main curves for the model calibration. In comparison of the proposed model with Model III-1, both simulate hysteresis curves with almost the same accuracy. The proposed model can be applied efficiently in analyzing the unsaturated flow.

• Korean Journal of Crystallography
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• v.12 no.4
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• pp.233-238
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• 2001

X-ray microdiffraction which uses x-ray beam focused down to a micron size from synchrotron radiation sources allow precision measurements of local orientation and strain variations in polycrystalline materials. Using x-ray microdiffraction setup at Pohang Light Source, we investigated the tex-ture of Cu interconnects with various widths on Si wafer by collecting Laue images and focused to about 2×3㎛ ² in size. Our results show that 1㎛ wide Cu interconnect had grains in rather ran- dom orientation. On the other hand the 20㎛ wide interconnects showed a 〈111〉fiber texture near the center. The grains were 2∼5㎛ long at the 1㎛ wide interconnect and 6∼8㎛ in size at the 20㎛ wide interconnect.