• The Journal of Korean Association of Computer Education
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• v.19 no.6
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• pp.69-80
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• 2016

As a 21C core skill, computational thinking has been focused recently, and computer programming education is popular in primary and secondary schools. This paper aims to analyze the computer programming learning results based on gender difference and verify the reasons causing the difference. In this research, we focused on students' abstract thinking level as a variable and used C programming language and the RUR-PLE. Also, in this research, we focused on the concept of abstraction, one of the main component of computational thinking. And then, we analyze 587 high school students' abstract thinking level and survey them in order to find a new method for enhancing programming skill. In addition, we analyzed the causes for the difference in how the abstract thinking level applies when the students understand various structures of computer programs. From the results, we can propose a computer programming education method that enhances students' merits and compensates their drawbacks in the near future.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.1-14
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• 2015

This study utilizes Monte Carlo simulation to forecast the time charter rate of vessels, the three-month Libor interest rate, and the ship demolition price, to mitigate future uncertainties involving these factors. The simulation was performed 10,000 times to obtain an exact result. For the empirical analysis - based on considerations in ordering ships in 2010-a comparison between the Monte Carlo simulation-based stochastic discounted cash flow (DCF) method and traditional DCF methods was made. The analysis revealed that the net present value obtained through Monte Carlo simulation was lower than that obtained via regular DCF methods, alerting the owners to risks and preventing them from placing injudicious orders for ships. This research has implications in reducing the uncertainties that future shipping markets face, through the use of a stochastic DCF approach with relevant variables and probability methods.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.399-404
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• 2003

Aliphatic polyester, especially poly(butylene adipate)(PBA), is quite biodegradable and one of the most promising polymer materials to be commercialized. Bis(4-hydroxybutyl) adipate (BHBA) formation stage is the first principal process in the production of PBA from adipic acid (AA) and 1,4-butane diol (BD). In this study, we investigated for the effective production of Bis(4-hydroxybutyl) adipate (BHBA), effects of molar ratio of adipic acid (AA) to 1,4-butane diol (BD), catalyst (tetrabutyl titanate, TBT) concentration, and temperature on the reaction rate of esterification between AA and BD were investigated. Initial reaction rate of the esterification decreased with increasing molar ratio of AA to BD and reaction temperature, whereas reaction constant increased with increase in catalyst-concentration. Activation energy values for catalyzed and uncatalyzed esterifications were 198.5 and 94.8 kJ/mol, respectively.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.81-87
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• 1977

Resistant and susceptible pine (Pinus thunbergii, Parl) trees to pine gall midge (Thecodiplosis japonensis, Uchida et Inouye) were selected and monoterpene composition in one year old branches, shoots and needles of both groups have been analysed by GLC. The results are summarized as follows; 1. Monoterpene composition in either one year old branches or shoots were not affected by their directions (North or South). 2. Major monoterpenes in one year old branches were ${\alpha}-pinene,\;{\beta}-pinene$, myrcene, limonene, ${\beta}-phellandrene$ and terpinolene. 3. In addition to ${\alpha}-pinene$, camphene, ${\beta}-pinene$, myrcene, ${\Delta}^3-carene$, limonene, ${\beta}-phellandrene$ and terpinolene, several less volatile components which appear to be monoterpenes were also present in shoots and needles. 4. Compared with the susceptible pine, the resistant tree was found richer in limonene composition. 5. ${\beta}-Pinene$ composition in the resistant pine was less than that in the susceptible pine. 6. The difference in the composition of limonene or ${\beta}-pinene$ between two groups of pine trees was discussed in relation to the resistance to pine gall midge.

• Korean Journal of Agricultural Science
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• v.40 no.3
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• pp.221-226
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• 2013

Degrees of hydrolysis by alkaline protease produced from Serratia marcescens S3-R1 is 3.95-6.30% of whey proteins during 5, 15, 30, 60, 90, 120,180, 240 min incubation at $40^{\circ}C$. Proteolytic pattern of the whey proteins showed that various low molecular weight peptides were generated during the incubation periods. The biological function of in Raw 264.7 cells treated with whey protein hydrolytic peptides, anti-inflammatory effect showed exhibit in the expression of pro-inflammatory cytokines such as TNF-${\alpha}$, IL-6, COX-2 and iNOS by PCR analysis. COX-2 and iNOS gene expression inhibited in Raw 264.7 cells on whey protein hydrolysates below 3,000 dalton. The protease from Serratia marcescens S3-R1 showed a potential in production of low molecular weight whey protein hydrolysates which could be used for industrial application.

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.31-43
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• 2001

This study was performed to observe the micro-structure change of surface, behavior of oxide change of element, the component transformation of the alloy and the bonding strength between the porcelain interface in order to investigate effects of indium, tin on interfacial properties of porcelain fused to low gold alloy. Hardness of castings was measured with a micro-Vicker's hardness tester. The compositional change of the surface of heat-treated specimen was analyzed with an EDS and an EPMA. The interfacial shear bonding strength between alloy specimen and fused porcelain was measured with a mechanical testing system(MTS 858.20). The results were as follows: 1) The hardness value of alloy increased as increasing amount of indium addition. 2) The formation of oxidation increased as increasing indium and tin contents after heat treatment. 3) Diffusion of indium and tin elements increased as increasing indium and tin contents in metal-porcelain surface after porcelain fused to metal firing. 4) The most interfacial shear bonding strength was increased as increasing a composition of adding elements, and a heat-treatment time, and an oxygen partial pressure. From the results of this study it was found that the addition of alloying elements such as indium and tin increase hardness of as-cast alloy, produce surface oxide layer of adding elements by heat-treatment which may improve interfacial bonding strength between alloy and porcelain.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.59-60
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• 2018

The oscillating-water-column wave energy converter represents the complex physical characteristics associated with the water column, turbines, generator, and power converter. This study focuses on the derivation of the physical relationship between the water column and turbine based on the 1/ 4 scale model test. The aerodynamic characteristics of the OWC ducted turbine were simulated using an orifice. The turbine effect, a key element in the OWC-chamber performance evaluation, can be represented by the flow rate and pressure drop through the orifice. The turbine effect of OWC-WEC was confirmed to have a non-linear relationship from the measured flow rate and pressure drop in the model test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1113-1118
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• 2011

In order to evaluate the characteristics of solid-solid contact interfaces, reflection or transmission techniques involving normal-incidence longitudinal waves are generally used. However, these normal-incidence techniques are of limited use in field applications such as in the inspection of welded parts. The oblique-incidence ultrasonic technique may be an alternative for overcoming these problems. However, in this technique, the mode conversion at the contact interfaces should be taken into account along with the normal and tangential interface stiffness. In this study, we have suggested a theoretical model for obliqueincidence ultrasonic waves at the contact interfaces and analyzed their reflection and transmission characteristics. Experimental results showed that the measured reflection coefficient and second harmonic wave agreed well with the suggested theoretical model. Consequently, the oblique-incidence technique can be a promising method for evaluating the characteristics of the contact interfaces.

• Toxicological Research
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• v.14 no.3
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• pp.443-452
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• 1998

This sutdy was carried out to investigate the acute toxicity and foru-week intravenous toxicity of the intralipidos in rats and rabbits. The acute toxicity study of Intralipidos was performed in Spragur-Dawley (SD) rats. Intralipidos was administered by intravenous to maximum dose 200 ml/kg. $LD_{50}$ of intralipidos was found 139.5ml/kg and 153.8ml/kg in male female SD rats. Four-week toxicity of intralipidos using New Zealand White Rabbit and SD rats. The Rabbit and Rats were administered by intravenous seven days per week for 28 days, with dosage of 15, 6, 2 ml/kg/day and 20, 6, 2ml/kg/day, respectively. Animals treated with intralipidos did not cause any death and show any clinical signs. They did not show any significant changes of body weight, feed uptake and water consumption. They were not significantly different from the control group in urinalysis, ocular examination hematological, serum biochemical value and histopathological examination. Therefore, Intralipidos was not indicated to have any toxic effect in the Rabbits and Rats, when it was administrated by intravenous below the dosage 15ml/kg/day and 20 ml/kg/day for four weeks.

• Toxicological Research
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• v.14 no.3
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• pp.435-441
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• 1998

Alginase$Alginase^{ⓡ}$ (Arginine esterase) is one of the snake venoms which is mainly consisted of arginine esterase and acts as a thrombus -forming inhibitor/thrombus-lysin. These present studies were performed to investigate of the acute and subacute toxicity of the Alginase$Alginase^{ⓡ}$ in rats. In acute toxicity study, rats were single administered intravenously with dosages of 0.001, 0.01. 0.1, 1 and 10U/kg B.W. and examined the number of death, clinical sign, body weight and pathological change for 7days after administration of Alginase$Alginase^{ⓡ}$. At maximum dose level (10U/kg B.W.), Alginase$Alginase^{ⓡ}$ induced symptoms of shock with cyanosis and dyspnea. But these symptoms dissappeared after 30~50 minutes and we could not find any other toxic effect in rats. Therefore, $LD_{50}$ Value of Alginase was over 10U/kg B.W. in rats. In four-week intravenous toxicity study of Alginase$Alginase^{ⓡ}$, rats were administered intravenously seven days per week for 28 days, with dosages of 0, 0.0125, 0.125 and 1.25U/kg B.W./day, respectively. Alginase$Alginase^{ⓡ}$ did not caused any death and showed any clinical signs in rats. No significant Alginase$Alginase^{ⓡ}$ -related changes were found in feed uptake, water consumption, hematology, serum biochemistry, urinalysis, ocular examination, organ weight and histopathological examination. From the results, Alginase$Alginase^{ⓡ}$ seems not to have any toxic effect in rats when it were given daily intravenous injections below the dosage 1.25U/kg B.W./day for four weeks.