• Journal of the Korean GEO-environmental Society
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• v.21 no.1
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• pp.13-19
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• 2020

Recently, as the number of earthquakes increases in the Korean Peninsula and surrounding area, the importance of earthquake countermeasures and seismic design has been increasing. As a result, interest and concerns about liquefaction, which is one of the problems that concern the earthquake, are increasing. There are various methods that can assess the possibility of liquefaction by using geotechnical information for specific ground. However, direct comparisons of each method are not yet available. In this study, the two methods using the SPT-N value and the shear wave velocity among the methods for estimating the Cyclic Resistance Ratio (CRR) value required for the simplified liquefaction assessment method were compared. And the correction of the ground information required to use the two methods respectively was compared. As a result, more accurate evaluation results were obtained when the CRR value is calculated using the SPT-N values.

• Journal of the Korean GEO-environmental Society
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• v.23 no.5
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• pp.5-13
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• 2022

In this study, dynamic characteristics and liquefaction resistance characteristics of silica sand which is used to simulate sandy layer were conducted using the cyclic triaxial test according to the relative density difference. The difference in liquefaction resistance with the relative density was confirmed through the test results, which the relative density conditions were changed to 40%, 60%, and 80%, and the cyclic resistance ratio (CRR) curve of the silica sand was obtained. In addition, in order to examine the validity of the liquefaction resistance ratio (CRR) curve, artificial silica sand ground was created, and liquefaction potential was evaluated through the simple assessment method and the detailed assessment method, and the safety factors of each were compared.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.5
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• pp.197-209
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• 2020

Evidence of liquefaction during the 2017 Pohang earthquake has highlighted the urgent need to evaluate the current seismic design standard for liquefaction in Korea, particularly the liquefaction triggering standard. With the simplified method, which is the most popular method for evaluating liquefaction triggering, the factor of safety for liquefaction triggering is calculated via the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR). The parameters in the CSR and CRR have undergone changes over time based on new research findings and lessons learned from liquefaction case-histories. Hence, the current design standard for liquefaction triggering evaluation in Korea should also reflect these changes to achieve seismic safety during future earthquakes. In this study, liquefaction susceptibility criteria were discussed initially and this was followed by a review of the current liquefaction triggering codes/guidelines in other countries and Korea. Next, the parameters associated with the CSR such as the maximum ground acceleration, stress reduction factor, magnitude scaling factor, and overburden correction factor were discussed in detail. Then, the evaluation of the CRR using the SPT N-value and CPT qc-value was elaborated along with overburden and clean-sand correction factors. Based on this review of liquefaction triggering evaluation standards, recommendations are made for improving the current seismic design standard related to liquefaction triggering in Korea.

• Journal of the Korean earth science society
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• v.39 no.2
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• pp.131-138
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• 2018

The purpose of this study is to improve the quantitative precipitation estimation method based on satellite brightness temperature. The non-linear equation for rainfall estimation is improved by analysing precipitation cases around the Korean peninsula in summer. Radar reflectivity is adopted the CAPPI 1.5 and CMAX composite fields that provided by the Korea Meteorological Agency (KMA). In addition, the satellite data are used infrared, water vapor and visible channel measured from meteorological imager sensor mounted on the Chollian satellite. The improved algorithm is compared with the results of the A-E method and CRR analytic function. POD, FAR and CSI are 0.67, 0.76 and 0.21, respectively. The MAE and RMSE are 2.49 and 6.18 mm/h. As the quantitative error was reduced in comparison to A-E and qualitative accuracy increased in compare with CRR, the disadvantage of both algorithms are complemented. The method of estimating precipitation through a relational expression can be used for short-term forecasting because of allowing precipitation estimation in a short time without going through complicated algorithms.

• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.143-153
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• 2020

This study embodies and proposes VR color therapy healing contents 'Nornir' that can manage stress in daily life. "Nornir" applies the CRR analysis method to provide a customized VR color therapy experience according to the three colors selected by the user. It is designed to enable users to understand themselves through their color journey, to rec eive various color interactions and stimuli to implement in the future, and to provide healing that lowers stress levels. Based on the results implemented, the Korean version of the mood condition test 'K-POMS' was conducted before an d after the demonstration to check the user's stress changes after the content demonstration. Experiments have shown that users clearly see a decrease in negative emotions and an increase in positive emotions. By using VR technology, color psychotherapy rules are combined to provide the possibility of relieving stress for users who are exposed to fre quent stress in daily life.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.83-83
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• 2019

Increasing the CO₂ concentration in the atmosphere induce high temperature and rising sea levels. So the technology that capture and reuse of the CO₂ have been recently become popular. Among other methods, CRR(CO2₂ reduction reaction) is typical method of CO₂ reusing. Electrocatalyst can show more higher efficiencies in CRR than photocatalyst because it doesn't use nature source. Nowadays, finding high efficient electrocatalyst by controlling electronic (affected by stoichiometry) and geometric (affected by atomic arrangement) factors are very important issues. Mono-atomic electro-catalyst has limitations on controlling binding energy because each intermediate has own binding energy range. So the Multi-metallic electro-catalyst is important to stabilize intermediate at the same time. Carbon monoxide(CO) which is our target product and important feedstock of useful products. Au is known for the most high CO production metal. With copper, Not only gold/copper has advantages which is they have FCC packing for easily forming solid solution regardless of stoichiometry but also presence of adsorbed CO on Cu promotes the desorption of CO on Au because of strong repulsion. And gold/copper bi-metal catalyst can show high catalytic activity(mass activity) although it has low selectivity relatively Gold. Actually, multi-metallic catalyst structure control method is limited in the solution method which is takes a lot of time. In here, we introduce CTS(carbo thermal shock) method which is using heat to make MMNP in a few seconds for making gold-copper system. This method is very simple and efficient in terms of time(very short reaction time and using carbon substrate as a direct working electrode) and increasing reaction sites(highly dispersed and mixing alloy structures). Last one is easy to control degree of mixing and it can induce 5 or more metals in one alloy system. Gold/copper by CTS can show higher catalytic activity depending on metal ratio which is altered easily by changing simple variables. The ultimate goals are making CO₂ test system by CTS which can check the selectivity depending on metal types in a very short time.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.44-55
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• 1994

This paper describes the development of real-time irrigation reservoir operation models that adequately allocate available water resources for paddy rice irrigation. Water requirement deficiency index(WRDI) was proposed as a guide to evaluate the operational performance of release schemes by comparing accumulated differences between daily release requirements for irrigated areas and actual release amounts. Seven reservoir release rules were developed, which are constant release rate method (CRR), mean storage curve method(MSC), frequency analysis method of reservoir storage rate(FAS), storage requirement curve method(SRC), constant optimal storage rate method (COS), ten-day optimal storage rate method(TOS), and release optimization method(ROM). Long-term forecasting reservoir operation model(LFROM) was formulated to find an optimal release scheme which minimizes WRDIs with long-term weather generation. Rainfall sequences, rainfall amount, and evaporation amount throughout the growing season were to be forecasted and the results used as an input for the model. And short-term forecasting reservoir operation model(SFROM) was developed to find an optimal release scheme which minimizes WRDIs with short-term weather forecasts. The model uses rainfall sequences forecasted by the weather service, and uses rainfall and evaporation amounts generated according to rainfall sequences.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.4
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• pp.371-383
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• 2012

Shaping the root canal system to maintain original canal curvature is essential to clinical success in endodontic treatment. Opposed to most root canals that are curved, endodontic instruments are made from straight metal blanks. They have a tendency of straightening the root canal during preparation and frequently result in procedural errors. A new treatment method to maintain original canal curvature during shaping has been introduced for preventing procedural errors. The aim of this study was to compare the ability of instruments to maintain original canal curvature of continuous rotary system and single file system. Thirty ISO 15, 0.02 taper, Endo Training Blocks(Dentsplay Maillefer) were used. Specimens were assigned to 1 of 3 groups for shaping: specimens in group 1 were shaped with ProFile #20/.06 at the WL. Specimens in group 2 were shaped with Mtwo #35/.04 at the WL. Specimens in group 3 were shaped with WaveOne Primary reciprocating files at the WL after the glide path was achieved with PathFile. Pre- and postinstrumentation digital images were superimposed and processed with Matlab r2010b(The MathWorks Inc, Natick, MA) software to analyze the curvature-radius ratio(CRr), representing canal curvature modification. Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file were analyzed with 1-way ANOVA(P<.05). Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file system were analyzed with independent t-test(P<.05). A statistically significant difference(P<0.05) was noted on each Ni-Ti file. ProFile and WaveOne instrumentations maintained the original canal curvature significantly better(P<0.05) than Mtwo file. There were no significant difference(P>0.05) between continuous rotary system and single file system. Under the conditions of this study, ProFile and WaveOne instruments maintained the original curvature significantly better than Mtwo file and were less modification of the canal curvature compared. There was no significant difference between continuous rotary system and single file system in shaping of simulated canals. As clinical practitioners, it may be advantages to use hybrid approach when root canal shapes depending on the design and usage of Ni-Ti files.

• Communications for Statistical Applications and Methods
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• v.17 no.2
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• pp.293-308
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• 2010

In this paper, we examine the forecasting KOSPI 200 realized volatility by volatility measurements. The empirical investigation for KOSPI 200 daily returns is done during the period from 3 January 2003 to 29 June 2007. Since Korea Exchange(KRX) will launch VKOSPI futures contract in 2010, forecasting VKOSPI can be an important issue. So we analyze which volatility measurements forecast VKOSPI better. To test this hypothesis, we use 5-minute interval returns to measure realized volatilities. Also, we propose a new methodology that reflects the synchronized bidding and simultaneously takes it account the difference between overnight volatility and intra-daily volatility. The t-test and F-test show that our new realized volatility is not only different from the realized volatility by a conventional method at less than 0.01% significance level, also more stable in summary statistics. We use the correlation analysis, regression analysis, cross validation test to investigate the forecast performance. The empirical result shows that the realized volatility we propose is better than other volatilities, including historical volatility, implied volatility, and convention realized volatility, for forecasting VKOSPI. Also, the regression analysis on the predictive abilities for realized volatility, which is measured by our new methodology and conventional one, shows that VKOSPI is an efficient estimator compared to historical volatility and CRR implied volatility.

• Journal of Veterinary Clinics
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• v.15 no.1
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• pp.131-139
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• 1998

Progesterone을 함유하고 있는 CIDR(Controlled Internal Drug Release)의 질내삽 입은 황체기를 인위적으로 연장시킬 수 있다. CIDR의 삽입이,삽입시 존재했던 우세난포 (dominant follicle)의 반응과 난포의 발육반응 그리고 2회 또는 3회의 난포주기를 가지고 있는 처려우에서 CIDR의 삽입기간동안 난포의 성장 및 발육에 어떠한 영향을 미치는가를 비교검 토하기 위하여 배란후 16일째의 처녀우 4마리에 7일동안 CIDR를 삽입하였다. CIDR의 삽입 은 발정의 발현을 억제시켰으며 그리고 발정주기의 길이를 정상 발정주기보다 유의성있게 연 장시켰다($26.3{\pm} 0.5 vs 20.8{\pm}$ 1.5일, p<0.05). CIDR의 삽입시 혈장 progesterone 농도는 $3.6{\pm}$ 2.7 ng/ml 이었으며, 17일과 23일 사이에는 2.1-4.4 ng/ml($3.6{\pm}1.2 ng/ml$) 사이를 유지했다. 혈 장 estradiol-179의 농도는 난포의 발육 및 배란전 배란난포의 성숙을 나타내는 특징적인 변화 양상을 나타래었다. 4마리의 처녀우중 2마리는 CIDR 삽입전 발정주기당 2회의 난포주기를 가진 반면, 나머지 2마리는 주기당 3회의 난포주기를 가졌다. 그렇지만 CIDR의 삽입기간동안 모든 처녀우는 주기당 3회의 발정주기를 가졌다. CIDR의 삽입전 발정주기당 3회의 난포주기 를 갖는 처녀우에서 CRR의 삽입은 세 번째 난포주기에서 배란성 우세난포의 우세기 (dominant phase)를 연장시켰다. 3회의 난포주기를 갖는 2마리에서 CIDR의 삽입후 배란난포 는 존속시간과 우세기가 유의성있게 연장되었다. CIDR의 삽입전 발정주기당 2회의 난포주기 를 갖는 다른 2마리의 처녀우에서 CIDR의 삽입후 우세난포는 곧바로 퇴행되었고 새로운 난 포주기를 형성하였으며, 우세난포의 우세기와 배란난포의 존속기간을 연장시키지 않았다. CRR의 삽입은 CIDR의 삽입후 이어지는 발정주기동안 난포의 발육 및 성장에 영향을 미치 지 않았으며 발정주기의 길이, 난포주기, 혈장 progesterone 및 estradiol-179 농도에 영향을 미치지 않았다. 결과적으로 황체기 후반부에 CIDR의 삽입은 CIDR삽입전 발정주기동안 3회 의 난포주기를 갖는 처녀우에서 배란성 우세난포의 발육과 배란까지의 기간을 연장시켰고 2회 난포주기를 갖는 처녀우에서는 우세난포를 곧바로 퇴행시킨후, 새로운 난포주기를 형성 하였다.