• Land and Housing Review
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• v.8 no.4
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• pp.257-266
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• 2017

LH has been using ultra high strength reinforcing bars (SD500 and SD600), since 2011. Such a change requires an adjustment of the old extra rates of bar splice to reflect use of ultra high strength reinforcing bars, as these rates had been set based on SD400 bars. It is particularly difficult to calculate precisely rebar lap-splice locations for large areas, such as those in apartment buildings. This research aims to adjust the extra rates of bar splice to reflect a reasonable rate; the rebar lap-splice length is not an exact estimation, but instead, an extra rates of bar splice is set and the rebar lap-splice length is increased by 2% (D 10) - 7% (025) depending on the bar size. The subjects of this study are LH apartments undergoing frame construction. We studied the quantity estimations from the design drawings, and analyzed the settlement quantities of construction field. The results of the study revealed that, when each of the quantities are analyzed, consider adjusting the extra rates of bar splice of some rebar to 1% - 3.5%. This was caused by an overuse of reinforcing bars in onsite construction and the use of supporting bars that have not been reflected in the documents, among other reasons. Based on the results of our study, an improvement plan for the current extra rates of bar splice seems to be necessary, cutting or raising the rate depending on the analysis of the data. Through this study, we expect to contribute to the calculation of reasonable construction costs, improvements in the quality of rebar work, and improvements in the capacity of design techniques for apartment buildings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.595-600
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• 2020

The purpose of this paper was to prepare and evaluate solid dispersions (SD) that can increase the dissolution rate of dexibuprofen as a model drug with low solubility in water using saccharides and sugar alcohols as dispersion materials. DSC, XRD, content and content uniformity test, dissolution test, and disintegration test were conducted for physicochemical evaluation of the prepared SD. For the results, it was confirmed using differential scanning calorimetry that fructose, which has a melting point around 120 ℃ of the device operating temperature range, is a suitable excipient for the preparation of SD by the rotary hot-melt granulation (RHMG) method. X-ray diffraction analysis was conducted to confirm that the crystallinity of dexibuprofen was reduced. Disintegration test of the prepared tablet using SD-containing dexibuprofen and fructose confirmed a very fast disintegration time within 1~2 seconds and also showed that the dissolution rate was about 20% faster than that of the dexibuprofen raw material. Dexibuprofen with reduced crystallinity by SD confirmed through the RHMG method can be used to increase the dissolution rate of the drug and increase the disintegration time of the tablet. Thus, it can be used in the manufacturing of various solid preparations.

• Toxicological Research
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• v.14 no.2
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• pp.151-156
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• 1998

Acetaminophen (APAP) and gentamicin are widely used for many patients, but little in-formation is available regarding the combined effects of APAP and gentamicin. This study was aimed to investigate the potent nephrotoxicity following combined-treatment with APAP and gentamicin. Serum biochemical parameters and histopathological changes in the kidney were observed in female SD rats after continuous daily treatment with either 600 mg/kg/day APAP, and/or 300 mg/kg/day gentamicin for 3 days, and compared with saline sham-treated control animals. APAP and gentamicin combination-treated rats exhibited inconsistent increasing tendency in blood urea nitrogen (BUN) by 96 hours after the last treatment, compared to control or the animals treated with each drug. The relative kidney weights were also increased. Histopathological findings of kidneys revealed that necrosis of proximal convoluted tubules were higher in rats treated with APAP and gentamicin combination than the rats treated with each drug alone. These results suggest that combination use of both drugs have more severe nephrotoxicity than treating each drug alone.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.301-305
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• 2016

We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.532-534
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• 2000

복합적인 감성기반 영상 검색 시스템을 구축하기 위해서는 감성속성으로 영상을 찾는 검색은 물론이고, 주어진 영상의 감성특성을 알아내는 과정이 필요하다. 본 논문에서는 영상의 특성으로부터 감성을 매핑하는 신경망을 구축하고 다양한 실험으로 그 가능성을 보인다. 여기에서 영상특징으로 웨이블렛계수와 위치정보를 사용했고, 감성공간으로는 SD법으로부터 14개의 형용사쌍을 추출했다. 이 두 공간의 매핑에 사용된 신경망의 입력으로 영상에서 얻은 RGB 색상당 36개의 총 108개의 웨이블렛 개수를 사용했고, 출력은 14개의 감속속성당 7등급으로 총 98개로 구성했다. 총 6명이 영상을 보고 평가한 감성평가데이터중에서 2명이 각각 평가한 데이터로 신경망을 학습시키고 나머지 10개로 테스트한 경우는 90%이상의 인식률을 보였다. 4명이 각각 90개씩 평가한 데이터로 신경망을 학습시키고 나머지 10개로 테스트한 경우는 90%의 인식률을 보였다. 또한 공통된 감성을 신경망을 통해 인식할 수 있는지 판단하기 위해 600개씩 2명으로부터 얻은 1200개의 데이터에 대해서 1000개를 학습시키고 200개를 테스트하고, 100개씩 4명으로부터 데이터에 대해서 360개를 학습시키고 40개를 테스트해 본 결과, 전자의 경우 오류율 8, 후자의 경우 0.7~0.8 범위였다.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.2
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• pp.138-146
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• 2017

The aim of this study was to estimate time of biomineralization in developmental stages of rat lower incisors. Eruption length was measured. Four stages of incisor development were identified on histologic and microscopic computerized tomography (micro-CT) sections: (1) preodontoblast, (2) dentin matrix secretion, (3) enamel matrix secretion, and (4) enamel calcification. The overall eruption rate of the rat lower incisor was $600{\pm}70{\mu}m/day$ ($mean{\pm}SD$; n = 12). The length of the enamel secretion was $4.59{\pm}0.75mm$ in histologic section, was $3.64{\pm}0.63mm$ in radiographic section, which converts to $180.4{\pm}30.0hours$, $145{\pm}25hours$ respectively (n = 24). These findings suggested that the four biomineralizing developmental stages of the rat incisor took only several days. The significance of this animal study was to provide understanding for the rapid biomineralization process of developing rat tooth germ by analysis of tooth forming period.

• Journal of the Korea Concrete Institute
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• v.29 no.4
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• pp.335-343
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• 2017

This paper aims at investigating the bending strength of high-strength concrete beams with compressive strength of 80 MPa. The experimental parameters included nominal yielding strength of rebar with 400 and 600 MPa, rebar ratio ranging from 0.98 to 1.97%, and shear span-effective depth ratios (a/d) of 6.0 and 4.8. Experimental results were discussed regarding load-deflection relationship, ductility, bending strength, and prediction of bending strength of beams. Test results indicate that the use of high-strength rebar increased bending strength but decreased ductility. As span-effective depth ratio increased, the ductility of test beams decreased. In addition, test results of bending strength were compared with predictions from the current KCI code, Eurocode 2 and Korean Highway Design Specification (KHDC). The design code predictions for bending strength underestimated the experimental results. Therefore, the current design code predictions for bending strength of high-strength concrete beams would provide conservative design. Predictions of bending strength from KCI code using strength reduction factors and those from Eurocode 2 as well as KHDC using material factors were similar each other.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.4
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• pp.600-607
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• 2013

This study was performed to investigate the repeated-dose toxicity of Leuconostoc citreum GR1 (Leuc. citreum GR1), a lactic acid bacterium isolated from kimchi, in male and female rats. Sprague-Dawley male and female rats were divided into four group (ten animals in each group) and Leuc. citreum GR1 was administered daily by gavage to rats at dosage levels of 0, 500, 1,000, or 2,000 mg/kg/day for four weeks. There were no bacterial-related deaths or abnormal clinical signs in either gender of rats during the observation period. Furthermore, no differences were found between the control and treatment groups in terms of body weight, food intake, and water consumption. Hematological parameters, serum biochemical analysis, and histopathological examination also showed insignificant dose-dependent alterations. There were also no alterations in organ weights upon administration of Leuc. citreum GR1 alone. These results suggest the oral application of Leuc. citreum GR1, up to a dosage level of 2,000 mg/kg, causes no adverse effects in both male and female rats.

• Journal of the HCI Society of Korea
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• v.10 no.2
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• pp.13-19
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• 2015

Display technology has recently made enormous progress. In particular, display companies are competing each other to develop flexible display. Curved display, as a precursor of flexible display, are now used for smart phones and TVs. Curved monitors have been just introduced in the market, and are used for office work or entertainment. The aim of the current study was to investigate whether the curvature of a 42" multi-monitor affects postural control when it is used for entertainment purpose. The current study used two curvature levels (flat and 600mm). Ten college students [mean(SD) age = 20.9 (1.5)] with at least 20/25 visual acuity, and without color blindness and musculoskeletal disorders participated in this study. In a typical VDT environment, each participant played a car racing video game using a steering wheel and pedals for 30 minutes at each curvature level. During the video game, a pressure mat on the seat pan measured the participant's COP (Center of Pressure), and from which four measures (Mean Velocity, Median Power Frequency, Root-Mean-Square Distance, and 95% Confidence Ellipse Area) were derived. A larger AP (Anterior-Posterior) RMS distance was observed in the flat condition, indicating more forward-backward upper body movements. It can be partly due to more variability in visual distance across display, and hence longer ocular accommodation time in the case of the flat display. In addition, a different level of presence or attention between two curvature conditions can lead to such a difference. Any potential effect of such a behavioral change by display curvature on musculoskeletal disorders should be further investigated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.148-156
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• 2020

The paper is a summary of the results of the basic pullout test which is conducted to evaluate the anchorage capacity of high strength headed bars that is mechanical anchored vertically on steel fiber reinforced concrete members. The main experimental parameters are volume fraction of steel fiber, concrete strength, anchorage length, yield strength of headed bars, and shear reinforcement bar. Both sides of covering depth of the specimen are planned to double the diameter of the headed bars. The hinged point is placed at the position of each 1.5𝑙_dt and 0.7𝑙_dt around the headed bars, and the headed bars are drawn directly. As a result of pullout test experiment, concrete fracture and steel tensile rupture appear by experimental parameters. The compressive strength of concrete is 2.7~5.4% higher than that of steel fiber with the same parameters, while the pullout strength is 20.9~63.1% higher than that of steel fiber without the same parameters, which is evaluated to contribute greatly to the improvement of the anchorage capacity. The reinforcements of shear reinforcements parallel to the headed bars increased 1.7~7.7% pullout strength for steel fiber reinforced concrete, but the effect on the improvement of the anchorage capacity was not significant considering the increase in concrete strength. As with the details of this experiment, it is believed that the design formula for the anchorage length of KCI2017and KCI2012 are suitable for the mechanical development design of SD600 head bar that is perpendicular to the steel fiber reinforced concrete members.