• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.1
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• pp.13-24
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• 1983

A mathematical model for the two-dimensional unsteady flow was developed by introducing Abbott's implicit finite difference operator and double sweep algorithm, which could be applied to simulate the respose of a harbor against the intrusion of long waves through the entrance connected to open sea. In order to improve its accuracy corresponding to the field phenomena, bottom resistance, Coriolis force, wind effect terms were included and wave direction and radiating effect was considered. The result of seiche test was always stable and the amplitude was accurate. Some phase shift was occured, but it could be reduced by using small values of Courant number and many points per a wave length as well. A comparision with the Ippen and Goda's theoritical and hydraulic experimental works was fulfilled.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.99-113
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• 1996

Taurine, a ${\beta}$-amino acid, plays an important role as a neuromodulator and is necessary for the normal development of the brain. Since de novo synthesis of taurine in the brain is minimal and in vivo studies suggest that taurine does not cross the blood-brain barrier, the blood-cerebrospinal fluid (CSF) barrier is likely to play a role in taurine transport between the central nervous system and the systemic circulation. Therefore, we examined in vivo elimination of taurine from the CSF in the rat to characterize in vivo kinetics of elimination for taurine from the CSF is consistent with the in vitro study. Using a stereotaxic device, cannulaes were placed into the lateral ventricle and the cisterna magna of the rat. Radio-labelled taurine and inulin (a marker of CSF flow) were injected into the lateral ventricle, and the concentrations of the labelled compounds in the CSF were monitored for up to 3 hrs in the cisterna magna. The apparent clearance of taurine from CSF was greater than the estimated CSF flow (p<0.005), indicating that there is a clearance process in addition to the CSF flow. Taurine distribution into the choroid plexus was at least 10 fold higher than that found in other brain areas (e.g., cerebellum, olfactory bulb and cortex). When unlabelled taurine was co-administered with radio-labelled taurine, the apparent clearance of the labeled taurine was reduced (p<0.01), suggesting a saturable disposition of taurine from CSF. Distribution of taurine into the choroid plexus, cerebellum, olfactory bulb and cortex was similarly diminished, indicating that the saturable uptake of taurine into these tissues is responsible for the non-linear disposition. A pharmacokinetic model involving first order elimination and saturable distribution described these data adequately. The Michaelis-Menten rate constant estimated from in vivo elimination study is similar to that obtained in the in vitro uptake experiment Collectively, our results demonstrate that taurine is transported in the choroid plexus via a taurine is cleared from the CSF via a saturable process. This process may be functionally relevant to taurine homeostasis in the brain.

• Biomolecules & Therapeutics
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• v.14 no.2
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• pp.90-95
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• 2006

CKD-602 exerts its antitumor effect via inhibition of topoisomerase I in cancer cells. Multicellular spheroid (MCS) and Multicellular layers (MCLs) are known as in vitro 3-dimensional models which closely represent tumor conditions in vivo. In order to investigate the potential of CKD-602 against human colorectal tumors, we evaluated the anti-proliferative activity and penetration ability of CKD-602 in MCS and MCL cultures of DLD-l human colorectal cancer cells, respectively. The maximum effects($E_{max}$) induced by CKD-602 were significantly lower in MCS compared to monolayers (48% vs 92%). With prolonged drug exposure, the $IC_{50's}$ of CKD-602 decreased to $23.5{\pm}1.0nM$ in monolayers after 24 h exposure and $42.3{\pm}1.7nM$ in MCS after 6 days, respectively. However, no further increase in effect was observed for exposure time longer than growth doubling time (Td) in both cultures. Activity of CKD-602 was significantly reduced after penetration through MCL and also with cell-free insert membrane. In conclusion, CKD-602 showed significantly decreased anti-proliferative activity in 3D cultures (MCS) of human colorectal cancer cells. Tumor penetration of CKD-602 could not be determined due to loss of activity after penetration through cell free insert membrane, which warrants further evaluation using a modified model.

• Journal of Preventive Medicine and Public Health
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• v.27 no.1 s.45
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• pp.107-116
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• 1994

The United States adopted DRG based prospective payment system (PPS) in order to control the inflation of health care costs. No study used statistical test while many studies reported the cost containing effect of the PPS. To study impacts of the PPS on the Medicare expenditure, this study set the following three hypotheses (1) The PPS decelerated the increase in the hospital expenditure (Part A), (2) the PPS accelerated the increase in the expenditure of outpatients and physicians (Part B), (3) the increase in total expenditure was decelerated inspite of the spill over (substitution) effect because saving in the Part A expenditure were greater than losses in the Part B expenditure. The dependent variables are per capita hospital expenditure, per capita Part B expenditure, and per capita total expenditure for the Medicare beneficiaries. An intervention analysis, which added intervention effect to the time series variation on the Box-Jenkins model, was used. The observations included 120 months from 1978 to 1987. The results are as follows : (1) The annual increase in the per capita Part A expenditure was $5.11 after the implementation of DRG where as that before the PPS had been $11.1. The effect of the reduction ($5.99) was statistically significient (t=-3.9). (2) The spill over (substitution) effect existed because the annual increase in the per capita Part B expenditure was accelerated by $1.73 (t=1.91) after the implementation of the PPS. (3) The increase in the total Medicare expenditure per capita was reduced by $4.26 (t=-2.19) because the spill over effect was less than cost savings in the Part A expenditure.

• Korean Journal of Pharmacognosy
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• v.48 no.4
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• pp.298-303
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• 2017

To know the anti-oxidative effect of Epimedii Herba (Berberidaceae), the methanol extract of this plant was investigated by using a Caenorhabditis elegans model system. The methanol extract of this plant showed relatively significant DPPH radical scavenging and superoxide quenching activities. The ethyl acetate soluble fraction of Epimedii Herba (EHE), which showed the most potent DPPH radical scavenging and superoxide quenching activities, was tested on its effects on superoxide dismutase (SOD), catalase, intracellular ROS, and oxidative stress tolerance in Caenorhabditis elegans. Furthermore, in order to verify that regulation of stress-response genes is responsible for the increased stress tolerance of the EHE treated C. elegans, we checked SOD-3 expression using a transgenic strain. As a result, the EHE increased SOD and catalase activities of C. elegans, and reduced intracellular ROS accumulation in a dose-dependent manner. Besides, EHE-treated CF1553 worms showed higher SOD-3::GFP intensity than that of non-treated controls.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.148-156
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• 2000

For the in-line three cylinder engine whose crankshaft has a phase of 120 degrees, the total sum of unbalanced inertia forces occurring in each cylinder will be counterbalanced among three cylinders. However, parts of inertia forces generated at the No.1 and No.3 cylinders will cause a primary moment about the No.2 cylinder. In order to eliminate this out-of-balance moment, a single balance shaft has been attached to the cylinder block so that the engine durability and riding comfort may be further improved. Accordingly, the forced vibration analysis of the in-line three cylinder engine must be implemented to meet the required targets at an early design stage. In this paper, a method to reduce noise and vibration in the 800cc, in-line three cylinder LPG engine is suggested using the multibody dynamic simulation. The static and dynamic balances of the in-line three cylinder engine are investigated analytically. The multibody dynamic model of the in-line three cylinder engine is developed where the inertia properties of connecting rod, crankshaft, and balance shaft are extracted from their FE-models. The combustion pressure within the No.1 cylinder in three significant operating conditions(1500rpm-full load, 4000rpm-full load and 7000rpm-no load)is measured from the actual tests to excite the engine. The vibration velocities at three engine mounts with and without balance shaft are evaluated through the forced vibration analysis. Obviously, it is shown that the vibration of the in-line three cylinder engine with balance shaft is reduced to the acceptable level .

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.3
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• pp.1-11
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• 2014

Recently, major cities in Korea are suffering from frequent urban flooding caused by heavy rainfall. Such urban flooding mainly occurs due to the limited design capacity of the current drainage network, which increases the vulnerability of the cities to cope with intense precipitation events brought about by climate change. In other words, it can be interpreted that runoff exceeding the design capacity of the drainage network and increased impervious surfaces in the urban cities can overburden the current drainage system and cause floods. The study presents the green roof as a sustainable solution for this issue, and suggests the pre-design using the LID controls model in SWMM to establish more specific flood prevention system. In order to conduct the computer simulation in connection with Korean climate, the study used the measured precipitation data from Cheonan Station of Korea Meteorological Administration (KMA) and the forecasted precipitation data from RCP 8.5 scenario. As a result, Extensive Green Roof System reduced the peak runoff by 53.5% with the past storm events and by 54.9% with the future storm events. The runoff efficiency was decreased to 4% and 7%. This results can be understood that Extensive Green Roof System works effectively in reducing the peak runoff instead of reducing the total stormwater runoff.

• The Journal of Korean Medicine
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• v.33 no.3
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• pp.33-45
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• 2012

Objectives: Recent data have revealed that the plasma concentration of inflammatory mediators is increased in the insulin-resistant states of obesity and type 2 diabetes. The purpose of this study was to investigate the antidiabetic and anti-obesity effect of Massa Medicata Fermentata on obese type 2 diabetes mice. Methods: In order to examine the effects of Massa Medicata Fermentata, obese type 2 diabetes mice induced by Surwit's high fat, high sucrose diet. Mice were divided into 4 groups of ND (normal diet), HFD (high fat and high sucrose diet), Met (high fat and high sucrose diet with metformin) and MMF (high fat and high sucrose diet with Massa Medicata Fermentata) and investigated over 8 weeks. Diabetic and obese clinical markers, including body weight, glucose level, lipid level, leptin concentration, epididymal fat pad and liver weights and adipose tissue macrophage (ATM) were determined. Results: Compared with the HFD group, body weight, fructosamine, triglyceride, epididymal fat pad weight and ATM were significantly reduced in the MMF group. Conclusions: From the above results, the intake of Massa Medicata Fermentata may be effective in anti-hyperglycemia and anti-obesity by the attenuation of glucose and lipid levels and also inflammation state. Massa Medicata Fermentata may be beneficial for controlling diabetes mellitus type 2 in humans.

• Geotechnical Engineering
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• v.13 no.4
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• pp.55-66
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• 1997

In order to investigate the influence of installation angle of reticulated root piles(RRP) on their lateral load capacities, model tests of lateral loads on RRP with various installation angles $0^{\circ}\;, 5^{\circ}\;, 10^{\circ}\;, 15^{\circ}\;, 20^{\circ}\;,and 25^{\circ}$ are carried out. One set of RRP consists of 12 piles which are installed in circular patterns forming two concentric circles, each of which has 6 piles. Each pile made of a steel bar of 5mm in diameter and 350mm in length, is coated with sand until the bar has the diameter of 6.5mm. According to the test results, RRP's response is travily influenced by the displacement level. At low displacement level(1m), lateral load capacity increases as the installation angle is increased. However, the value of the optimum installation angle decreases as the displacement level is increased. In fact, it is found to be $17.5^{\circ}$ at 6mm lateral displacement. The ratios of the lateral resistances for the optimum installation angles to those for the vertical RRP decrease as the lateral displacements are increased. Thus the effect of slant ins angle of RRP is expected to be reduced at higher level of lateral displacement.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.548-553
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• 2002

We have investigated the output characteristics of a Nd:YAG oscillator with a Stimulated Brillouin Scattering phase conjugation mirror (SBS-PCM). FC-75 is used as an SBS gain medium and Cr:YAG (T=50%) as a Q-switcher. The SBS-PCM consists of an SBS-cell and a simple plano-convex focusing lens system. For the case of not using a Q-switcher, an SBS-cell doesn't work as a phase conjugation mirror. For the case of using a Q-switcher, the energy characteristics remains nearly the same whether using the SBS-cell or not using it. The pulse width is reduced from 50 ns to 40 ns by an SBS-PCM. When the SBS-cell is used with a Q- switcher, the SBS-cell works very well as a phase conjugation mirror and its beam-profile is improved dramatically. And in order to explain the progression of beam-profile, we propose a simple model based on the nonlinear reflectivity of the SBS-PCM, whose reflectivity is dependent on the pumping intensity at the focal plane.