• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.240-249
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• 2022

Measuring chlorophyll fluorescence (CF) is a useful tool for assessing a plant's ability to tolerate abiotic stresses such as drought, waterlogging and high temperature. Korean ginseng is highly sensitive to water stress in paddy fields. To evaluate the possibility of non-destructively diagnosing waterlogging stress using chlorophyll fluorescence (CF) imaging techniques, we screened 57 ginseng accessions for waterlogging tolerance. To evaluate waterlogging tolerance among the 2-year-old Korean ginseng accessions, we treated ginseng plants with water stress for 25 days. The physiological disorder rate was characterized through visual assessment (an assigned score of 0-5). The physiological disorder rates of Geumjin, Geumsun and GS00-58 were lower than that of other accessions. In contrast, lines GS97-62, GS97-69 and GS98-1-5 were deemed susceptible. Root traits, chlorophyll content and the reduction rates decreased in most ginseng accessions. Further, these metrics were significantly lower in susceptible genotypes compared to resistant ones. All CF parameters showed a positive or negative response to waterlogging stress, and this response continuously increased over the treatment time among the genotypes. The CF parameter Fv/Fm was used to screen the 57 accessions, and the results showed clear differences in Fv/Fm between the susceptible and resistant genotypes. Susceptible genotypes had an especially low Fv/Fm value of less than 0.8, reflecting damage to the reaction center of photosystem II. It is concluded that Fv/Fm can be used as a CF parameter index for screening waterlogging stress tolerance in ginseng genotypes.

• Korean journal of applied entomology
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• v.57 no.4
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• pp.261-269
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• 2018

The cowpea aphid Aphis craccivora Koch (Hemiptera: Aphididae) is a polyphagous species with a worldwide distribution. We investigated the temperature effects on development periods of nymphs, and the longevity and fecundity of apterous female of A. craccivora. The study was conducted at six constant temperatures of 10.0, 15.0, 20.0, 25, 30.0, and $32.5^{\circ}C$. A. craccivora developed successfully from nymph to adult stage at all temperatures subjected. The developmental rate of A. craccivora increased as temperature increased. The lower developmental threshold (LT) and thermal constant (K) of A. craccivora nymph stage were estimated by linear regression as $5.3^{\circ}C$ and 128.4 degree-days (DD), respectively. Lower and higher threshold temperatures (TL, TH and TH-TL, respectively) were calculated by the Sharpe_Schoolfield_Ikemoto (SSI) model as $17.0^{\circ}C$, $34.6^{\circ}C$ and $17.5^{\circ}C$. Developmental completion of nymph stages was described using a three-parameter Weibull function. Life table parameters were estimated. The intrinsic rate of increase was highest at $25^{\circ}C$, while the net reproductive rate was highest at $20^{\circ}C$. Biological characteristics of A. craccivora populations from different geographic areas were discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.1
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• pp.35-40
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• 2007

Cobalt ($Co^{2+}$) doped yttria stabilized cubic zirconia (YSZ, $Y_2O_3\;:\;25{\sim}50wt%$) single crystals grown by a skull melting method were heat-treated in $N_2\;at\;1000^{\circ}C$ for 5 hrs. The reddish brown single crystals were changed into either violet or blue color, respectively. Before and after heat treatment, the Co-doped YSZ crystals cut for wafers (${\phi}6.5{\times}t\;2mm$) and round brilliant (${\phi}10mm$). The optical and structural properties were examined by UV-VIS spectrophotometer and XRD. These results are analyzed absorption by $Co^{2+}\;(^4A_2(^4F)\to{^4P})\;and\;Co^{3+}$, change of energy gap and lattice parameter.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.548-554
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• 1997

The single crystal of $Mg_{0.16}Zn_{0.84}$Te:Co(Co:0.01 mole%) was grown by vertical Bridgman method. The crystal structure of $Mg_{0.16}Zn$_{0.84}$Te:Co and optical absorption properties of this compound were studied. The grown single crystal has a cubic structure and a lattice constant a=6.1422 $\AA$ were determined by X-ray diffraction. As a result of the optical absorption spectra of $Mg_{0.16}Zn_{0.84}$Te:Co, the intracenter transitions due to $Co^{2+}$ ions were detected for $A-band:^4A_2(^4F){\to}^4T_2(^4F),\; B-band:^4A_2(^4F){\to}^4T_1(^4F), C- band:^4A_2(^4F){\to}^4T_1(^4P)$.The charge transfer transition near the absorption edge was observed in the wavelength range of 550 to 770 nm. According to the crystal field theory, the crystal field parameter(Dq) and the Racah parameter(B) were determined.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.306-306
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• 2011

대상유역의 합리적인 홍수량 산정을 위해서는 풍부한 홍수자료를 바탕으로 직접적인 빈도해석을 적용하는 것이 가장 적정한 방법으로 알려져 있다. 하지만 국내의 대부분 유역은 관측된 홍수 자료가 제한적이고, 미계측 유역이므로 빈도해석을 통한 홍수량의 산정은 현실적으로 불가능한 실정이다. 이에 국내에서는 홍수량 산정에 대한 대안으로 강우-유출관계의 선형성을 가정한 집중형 강우-유출모형을 적용하고 있다. 하지만 집중형 강우-유출모형은 경험적인 공식에 의해 결정되는 수문매개변수의 비합리성 및 유역분할, 유역 하도추적의 구축방식에 따라 상이한 홍수량이 산정되는 문제점이 지적되고 있다. 따라서 최근에는 경험적이고 개념적인 집중형 유출모형을 지양하고, 격자체계를 기반으로 하고 있는 분포형 강우-유출모형의 연구가 활발히 진행되고 있는 상황이다. 본 연구의 목적은 남강 유역에서의 분포형 강우-유출모형 적용성 검증에 있다. 따라서 남강 유역 내에 발생한 4개의 호우사상을 선정한 후 강우 레이더 영상인 CAPPI영상 및 C-Max영상을 이용하여 면적강우량을 산정하였다. C-Max 영상을 이용하여 산정된 면적강우량은 지점강우를 이용한 면적강우량과 비교해 130%이상 과대 산정되는 경향을 나타낸 반면, CAPPI 영상을 이용하여 산정된 면적강우량은 10%이하의 오차를 나타내었다. 따라서 본 연구에서는 CAPPI 영상을 분포형 유출 모형인 VfloTM에 입력하여 유출을 모의 하였다. 모의된 유출곡선과 관측된 유출곡선을 비교 검토한 결과 80%이상의 높은 상관성을 나타낸 반면 첨두유출량 오차는 30%이상의 오차를 나타내었다. 하지만 강우보정기법인 G/R보정 기법을 적용한 후에는 첨두유출량 오차가 10%미만으로 감소하는 것으로 나타났다. 따라서 남강 유역에 분포형 유출모형을 적용하기 위해서는 다양한 강우 사상에 대한 지속적인 연구가 수행되어야 할 것으로 판단된다.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.637-647
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• 1997

As stated in Part(I), the use of the isolator is meant to protect a structure from seismic risk, by concentrating the inelastic deformations to relatively cheap and replaceable devices while the rest of the structures remains elastic. This research has been carried out to investigate the effects of various structural parameters and isolator characteristics on the seismic response of Base Isolated Bridges. Simplified analysis method for practical design is developed by using the results. The Proposed Code-Type approach method can be used to estimate the inertial forces accurately, not only at the isolator but throughout the height of the Base-Isolated Bridges. The proposed method is recommended to use in preliminary design tool or even a final design tool for Base Isolated Bridges. For the validation of simplified design method, examples with artificial earthquake time history and design response spectrum for P.C Box Bridge with bilinear hysteretic steel damper are evaluated.

• Journal of the Korean Magnetics Society
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• v.9 no.4
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• pp.190-195
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• 1999

The crystallographic and magnetic properties of the system of $Fe_{1-x}Co_x$(x=0.2 and 0.4) prepared by microwave arc-melting with the maximum power of 3.5 kW and a iron-foil with thickness of 25 ${\mu}{\textrm}{m}$ have been studied by the methods of X-ray diffraction and the measurement of the magnetic hysteresis using the vibrating sample magnetometer at room temperature. The samples were prepared in three different ways: First, pellet form pressed under the pressure of 9,000 N/$\textrm{cm}^2$. Second, the sheet cold rolled. Third, thin sheet treated with the temperature of 90$0^{\circ}C$. The X-ray diffraction pattern of the sample prepared by the first method shows that the crystal structure of the sample is bcc as same as that of Fe with a good uniformity. The iron-foil has the coercivity of 43 Oe and the initial slope of magnetization of 0.328 emu/gOe. The coervicity and magnetization of the sample prepared by the second method increased as the Co content increased. But the initial slop of the magnetization decreased as the Co content increased. This means that the displacement of domain wall is suppressed by the increases of coercivity as the Co content increased. The saturation magnetization of the samples made by the third method increased. On the other hand, the coercivity of these samples decreased. The increase of saturation magnetization of the samples seems to be related to the changes in X-ray intensity after heat treatment. Also some magnetic parameters of the samples were calculated by using a simple model and compared with other values.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.1-10
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• 2013

Recently, the closed landfills are usually converted into parks or playground by the check the stability of landfill because they settle unevenly making them unsuitable for structures. When the closed landfill reuse, environmental and structural stability is important. To increase the bearing capacity and reduce the probable settlement of a foundation on waste disposal ground, a layer of geosynthetics(Geocell) is placed on the waste disposal ground. In this paper, the analysis of long-term settlement parameter correlation was performed, also the evaluation of bearing capacity reinforcement effect was conducted by field test. The settlement measured in the field, and input the same ground index when an integer to identify each model were compared by calculating the settlement. In addition, by adjusting the parameters of each model to identify the most similar to the value of field measurement parameters were calculated. Based on the analysis results, when the using the Park's model C(intermediate) = 0.0678, the expected settlement is similar to the field measurement results. Also, the bearing capacity of geocell reinforced ground is 1.193~1.554 times higher than that of unreinforced ground.

• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.581-589
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• 2004

This paper compares the fatigue behaviors of concretes subjected to flexural and split-tensional loadings, and proposes the fatigue reliability models based on experimental results and reliability analysis. The fatigue tests were performed for the specimens of $150 mm{\times}75 mm$ split tensional cylinders and $150 mm{\times}150 mm{\times}550 mm$ flexural beams under constant loadings at three levels (70, 80 and $90\%$) with 0.1 stress ratio, 20 Hz loading speed and sine wave. The reliability analysis on fatigue data was based on Weibull distribution of two-parameters. From fatigue test results, two criteria were proposed to reject the experimental fatigue data because of statistical variation of concrete fatigue data. Two parameters ($\alpha$and u) of Weibull distribution were obtained using graphical method, moment method and maximum likelihood method. The probability density function(P.D.F) and cumulative distribution function(C.D.F) of the Weibull distribution for fatigue life of pavement concrete were derived for various stress levels using parameters, $\alpha$ and u. The goodness-of-fit test by Kolmogorov-Smirnov test was acceptable at $5\%$ level of significance. Based on reliability analysis, a fatigue model for pavement concrete was proposed and compared from existing models.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.210-221
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• 2000

The population habitat and density of Korean scallops, Chlamys farreri, were investigated to estimate population ecological characteristics from samples randomly collected around Wando from November, 1998 to October, 1999. Age and growth of the Korean scallops were determined from their ring radii. Maturation and spawning were studied using data of ovary maturity stage, gonadosomatic index, and fecundity. Seawater temperature and specific gravity ranged from 7.6 to $25.9^{\circ}C$ and from 1.0188 to 1.0260, respectively. Also dissolved oxygen and pH ranged from 6.48 to 9.50 ppm and from 8.17 to 8.80. Rocky and gravel bottom had a maximum habitat density of $$28.83 inds/100m^2$$ , which accounted for 82.4 % of the overall habitat area. The relationship between shell length (SL, mm) and shell height (SH, mm) of the Korean scallops was fitted : SH=1.021 SL+2.211 $(R^2=0.989)$. The shell length-total weight (TW, g) relationship was $TW=0.0003; SL^{2.837};(R^2=0.980)$. Then von Bertalanffy growth parameters were estimated from a nonlinear regression method, and the values were as follows : $SH_{\infty}=117.4 mm$K=0.61/year,; and; t_0=-0.017 year., The 50 % maturity at age was 0.21 year with the shell height of 18.3 mm, and spawning occurred twice a year, that is, June/July and October. The relationship between fecundity (Fc) and shell length was$Fc=697.03 SL^{2.683}(R^2=0.984)$, and the fecundity-gonad weight (GW, g) relationship was Fc=10,076,090 GW+15,608,781 $(R^2=0.990)$.