• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.563-571
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• 2003

Dysfunction of mesangial cells has been contributed to the onset of diabetic nephropathy. Insulin like growth factors (IGFs) are also implicated in the pathogenesis of diabetic nephropathy. However, it is not yet known about the effect of high glucose on IGF-I and IGF-II secretion in the mesangial cells. Furthermore, the relationship between cAMP and high glucose on the secretion of IGFs was not elucidated. Thus, we examined the mechanisms by which high glucose regulates secretion of IGFs in mesangial cells. Glucose increased IGF-I secretion in a time- (>8 hr) and dose- (>15 mM) dependent manner (p<0.05). Stimulatory effect of high glucose on IGF-I secretion is predominantly observed in 25 mM glucose (high glucose), while 25 mM glucose did not affect cell viability and lactate dehydrogenase release. High glucose also increased IGF-II secretion. The increase of IGF-I and IGF-II secretion is not mediated by osmotic effect, since mannitol and L-glucose did not affect IGF-I and IGF-II secretion. 8-Br-cAMP mimicked high glucose-induced secretion of IGF-I and IGF-II. High glucose-induced stimulation of IGF-I and IGF-II secretion was blocked not by pertussis toxin but by SQ 22536 (adenylate cyclase inhibitor). Rp-cAMP (cAMP antagonist), and myristoylated protein kinase A (PKA) inhibitor amide 14-22 (protein kinase A inhibitor). These results suggest that cAMP/PKA pathways independent of Gi protein may mediate high glucose-induced increase of IGF-I and IGF-II secretion in mesangial cells. Indeed, glucose (>15 mM glucose) increased cAMP formation. In conclusion, high glucose stimulates IGF-I and IGF-II secretion via cAMP/PKA pathway in mesangial cells.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.504-508
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• 2003

We present a new point-diffraction interferometer, which has been devised for the three-dimensional profile measurement of light scattering rough surfaces. The interferometer system has multiple sources of two-point-diffraction and a CCD camera composed of an array of two-dimensional photodetectors. Each diffraction source is an independent two-point-diffraction interferometer made of a pair of single-mode optical fibers, which are housed in a ceramic ferrule to emit two spherical wave fronts by means of diffraction at their free ends. The two spherical wave fronts then interfere with each other and subsequently generate a unique fringe pattern on the test surface. A He-Ne source provides coherent light to the two fibers through a 2${\times}$l optical coupler, and one of the fibers is elongated by use of a piezoelectric tube to produce phase shifting. The xyz coordinates of the target surface are determined by fitting the measured phase data into a global model of multilateration. Measurement has been performed for the warpage inspection of chip scale packages (CSPs) that are tape-mounted on ball grid arrays (BGAs) and backside profile of a silicon wafer in the middle of integrated-circuit fabrication process. When a diagonal profile is measured across the wafer, the maximum discrepancy turns out to be 5.6 ${\mu}{\textrm}{m}$ with a standard deviation of 1.5 ${\mu}{\textrm}{m}$.

• Journal of Environmental Policy
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• v.11 no.2
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• pp.17-54
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• 2012

This paper researched market responses for listed companies in several industries affected by the major oil spill accident off the coast of Taean, in December 7, 2007. The Taean accident triggered considerable concerns in people over the possibility of potential future regulation in shipbuilding and petroleum industries. However, the accident also provided an unexpected business opportunity for environmental clean-up industry and shipbuilding industry. The oil spill triggered the acceleration of the enactment of policies that require all new oil tankers to be constructed with double hull, which is interpreted as a good news for shipbuilding industry. Increased public pressure coupled with the prospect of tightened regulation is expected to decrease the market values of firms in the affected business fields. The stock prices of shipbuilding companies dropped after the incident but dramatically surged after the enactment of the policy in January 31, 2008. Our study also found that companies with more extensive prior environmental disclosure had less negative market reactions during the first sixteen days following the accident.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.853-864
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• 2016

Meteo-tsunamis are tsunamis that are typically caused by strong atmospheric instability (e.g., pressure jumps) in low pressure systems, but some meteo-tsunamis in winter can be caused by local atmospheric instability in high pressure systems (e.g., the Siberian High). In this study, we investigated a meteo-tsunami event related to a high pressure system that occurred during winter on the Yellow Sea in 2005. Sea level data from tidal stations were analyed with a high-pass filter, and we also performed synoptic weather analyses by using various synoptic weather data (e.g., surface weather charts) collected during the winter season(DJF) of 2005. A numerical weather model (WRF) was used to analyze the atmospheric instability on the day of the selected event (21 Dec. 2005). On the basis of the results, we suggest that the meteo-tsunami triggered by the high pressure system occurred because of dynamic atmospheric instability induced by the expansion and contraction of the Siberian High.

• KSBB Journal
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• v.15 no.1
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• pp.80-83
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• 2000

Polyacetylenes were extracted from Korean ginseng using supercritical $CO_2$ Yield of extraction of panaxydol and panaxynol was increased as the pressure of supercritical $CO_2$ increased at the range from 200 to 300 bar. The optimal yields of panaxydol and panaxynol was achieved at 65 and $55^{\circ}C$, respectively. Methanol was applied as a modifier. The highest yield of panaxydol and panaxynol were 0.230 and 0.054 mg/g-dry weight at modifier concentration of 10%(w/w), 300 bar, and $65^{\circ}C$. When these results were compared to that of methanol-extraction, the recoveries of panaxydol and panaxynol by supercritical $CO_2$ extraction in SFE were 37.8 and 55.1%, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.902-906
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• 2004

A separation principle of the Takagj-Sugeno (T-S) fuzzy-model-based observer-control is investigated. When the premise variables are able to be measured or directly computed from the outputs of the T-S fuzzy system and the fuzzy inference rules for the plant, control, and observer share the premise parts, the T-S fuzzy-model-based observer and the T-S fuzzy-model-based control can be separately designed such that the global stabilizability is guaranteed by the fuzzy observer-based output-feedback control. In this case, the global separation principle is well established. On the other hand, when the premise variables are unmeasurable or cannot be computed from the outputs, they should also be estimated. We examine the separation principle of this case. If the decay rates of the T-S fuzzy-model-based control and observer are sufficiently fast, the global separation is assured. Otherwise we show that the separation principle holds locally.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.441-447
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• 2012

This paper presents a design technique of a Takagi-Sugeno (T-S) fuzzy-model-based $H_{\infty}$ controller for autonomous underwater vehicles (AUVs). The design procedure aims to render the stabilizing controller which satisfies performance of the diving control for AUVs in the presence of the disturbance. A nonlinear AUV is modeled by the T-S fuzzy system through the sector nonlinearity. By using Lyapunov function, the sufficient conditions are derived to guarantee the performance of robust depth control in the format of linear matrix inequality (LMI). To succeed for diving control of AUV, we add the constraints on the diving and pitch angles in the LMI conditions. Through the simulation, we confirm the effectiveness of the proposed methodology.

• 연구논문집
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• s.27
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• pp.75-86
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• 1997

Combined cycle power plant is a system where a gas turbine or steam turbine is used to produce shaft power to drive a generator for producing electrical power and the steam from the HRSG is expanded in a steam turbine for additional shaft power. Combined cycle plant is a one from of cogeneration. The temperature of the exhaust gases from a gas turbine ranges from $400^\circC$ to $600^\circC$, and can be used effectively in a heat recovery steam generator to produce steam. Combined cycle can be classed as a "topping(gas turbine)" and a "bottoming(steam turbine)" cycle. The first cycle, to which most of the heat is supplied, is called the topping cycle. The wasted heat it produces is then utilized in a second process which operates at a lower temperature level and is therefore referred to as a "bottoming cycle". The combination of gas/steam turbine power plant managed to be accepted widely because, first, each individual system has already proven themselves in power plants with a single cycle, therefore, the development costs are low. Secondly, the air as a working medium is relatively non-problematic and inexpensive and can be used in gas turbines at an elevated temperature level over $1000^\circC$. The steam process uses water, which is likewise inexpensive and widely available, but better suited for the medium and low temperature ranges. It, therefore, is quite reasonable to use the steam process for the bottoming cycle. Only recently gas turbines attained inlet temperature that make it possible to design a highly efficient combined cycle. In the present study, performance analysis of a dual pressure combined-cycle power plant is carried out to investigate the influence of topping cycle to combined cycle performance.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.583-590
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• 2004

The autofocus is one of the important processes in the automated vision inspection or measurements using optical microscopes, because it influences the measuring accuracy. In this paper, we used the confocal microscope configuration based on not a pinhole but a single-mode optical fiber. A single mode fiber has the functions of source and detector by applying the reciprocal scheme. As a result, we acquired a simple system configuration and easy alignment of the optical axis. Also, we embodied a fast autofocus system by acquiring the focus error signal through a source modulation technique. The source modulation technique can effectively reduce physical disturbances compared with objective lens modulation, and it is easily applicable to general optical microscopes. The focus error signal was measured with respect to the modulation amplitude, reflectance of the specimen and inclination angle of the measuring surface. The performance of the proposed autofocus system was verified through autofocusing flat mirror surface. In addition, we confirmed that source modulation rarely degrades the depth resolution by the comparison between the FWHMs of axial response curves.

• Journal of Embryo Transfer
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• v.3 no.1
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• pp.13-23
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• 1988

These studies were undertaken to examine the interaction of tamoxifen with sex steroid hormones in rat uterine activity. The uterine wet weights of the immature Tat uterus were examined after the administration of estradiol-l7$\beta$(1$\mu$g), tamoxifen(50$\mu$g), progesterone(lmg). The uterotropic activity in immature ovariectomized rats was observed under various treatment conditions following pretreatment with above drugs. The results obtained were as follows:1) Tamoxifen produced significant increase (p <0.01) in uterine wet weight compared with control group, although the increase was not as great as that seen with estradiol-17$\beta$. Administration of estradiol-17$\beta$ together with tamoxifen inhibited significantly the increase of uterine wet weight by estradiol-17$\beta$ (p < 0.01). Coadministration of progresterone with tamoxifen partly blocked the increase of tamoxifen-induced uterine wet weights by progesterone. 2) Estradiol-17$\beta$after the estradiol-17$\beta$ pretreatment discontinued the declining uterine wet weights due to the absence of estrogen support, but uteri continued to increase in weight if daily estradiol-17 $\beta$ was maintained. Administration of tamoxifen on the fourth day of estradiol-17$\beta$ treatment reduced uterine wet weights within 24 hours, and the weights continued to decline with additional tamoxifen. 3) The modest growth of the uterus induced by three daily injections of 5Opg tamoxifen remained stable for five days, with or without additional tamoxifen treatment. Coadministration of tamoxifen with estradiol17$\beta$ increased slightly the increase of uterine wet weight by tamoxifen. Coadministration of tamoxifen with progesterone inhibited the increase of uterine wet weight by tamoxifen. 4) The modest growth of the uterus induced by three daily injections of lmg progesterone reduced uterine wet weight to the control level for five days. Commencement of tamoxifen or estadiol-17 $\beta$ injections on the fourth day of progesterone treatment rapidly elevated uterine wet weight.