• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.117-122
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• 2009

The hexagonal network-type PDMS microstructures were fabricated and they were employed to low-friction drag surfaces. While the lowest contact angle measured from the smooth surface was $108^{\circ}$ the highest contact angle measured from the microstructured surfaces was $145^{\circ}$ The moving speed of bullet-type capsule attached with a PDMS pad of smooth surface ($CA=108^{\circ}$) was 0.1261 m/s and that with a PDMS pad of microstructured surface ($CA=145^{\circ}$) was 0.1464 m/s. Compared with the smooth surface, the microstructured surface showed 16.1% higher moving speed. The network-type microstructures have a composite surface that is composed with air and PDMS solid. Therefore, the surface does not wet: rather water is lifted by the microstructures. Because of the composite surface, water shows slip-flow on the microstructures, and thus friction drag can be reduced.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.6
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• pp.485-491
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• 2015

This study was aimed to investigate the relaxation effects of Eucomiae Cortex (EC) extract in isolated rabbit corpus cavernosum smooth muscle and its mechanism. To evaluate the relaxation of EC extract in rabbit corpus cavernosum, EC extract was treated in corporal strips which were precontracted with phenylephrine(PE). To study its mechanism, Nω-nitro-L-arginine (L-NNA) was pretreated after infuse of EC extract and compared with non-treated. In calcium chloride (Ca²⁺) -free krebs solution, EC extract and Ca²⁺ 1 mM were infused by turns after Ca²⁺ 1 mM was treated into corporal strips contracted by PE. Cell ability, nitric oxide (NO) and epithelial nitric oxide synthase (eNOS) on human umbilical vein endothelial cell (HUVEC) were measured by MTT assay, Griess reagent system and histochemical, immunohistochemical methods. EC extract showed a significant relaxation effects on the corporal strips, this effects were inhibited by pretreatment of L-NNA. EC extract inhibited the increase of contraction by Ca²⁺ influx in Ca²⁺-free krebs solution, and eNOS positive reaction in corpus cavernosum, NO production in HUVEC increased by treatment of EC extract. These result suggest that the relaxation effects of EC extract in isolated corpus cavernosum smooth muscle are involved in increase of eNOS and NO production, blocking of extracellular Ca²⁺ influx.

• Korean Journal of Veterinary Research
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• v.33 no.2
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• pp.211-216
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• 1993

To elucidate the action of the cholinergic and ${\alpha}_2$-adrenergic nerve on the isolated ileal smooth muscle of the dog, effect a of electrical field stimulation were investigated on the pretreatment of the physostigmine; cholinestrase inhibitor, yohimbine; ${\alpha}_2$-adrenoceptor blocker, atropine ; cholinergic receptor blocker and phentolamine; non-selective $\alpha$-adrenoceptor blocker from physiograph. 1. The contractile response induced by electrical field stimulation was the frequency (2-40 Hz)-dependent manner. 2. The contractile response induced by electrical field stimulation was markedly increased by the pretreatment of physostigmine$(1{\mu}M)$; cholinestrase inhibitor. 3. The contractile response induced by electrical field stimulation was increased by the pretreatment of yohimbine$(1{\mu}M)$; ${\alpha}_2$-adrenoceptor blocker. These finding suggest that it was powerful excitatory action by cholinergic nerve and inhibitory action by ${\alpha}_2$-adrenergic nerve on ileal smooth muscle of the dog.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.3
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• pp.227-233
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• 2005

In order to estimate the effective horse power(EHP) in towing net of a bottom trawl ship, the ship's resistance was calculated by using a series data of Yamagata and Wigley formula. Also the effective horse power for a ship(EHPs) was estimated versus the ship speed in sailing and the propulsive efficiency was calculated with the brake horse power and the effective horse power. Then the effective horse power for a ship and a trawl net were estimated in the application of the propulsive efficiency in towing net. The total effective horse power($EHP_T$) was average 187.6kW and the effective horse power for a 1.awl net($EHP_n$) was average 176.7kW at a smooth sea state in towing net. The ratio of $EHP_n$ to $EHP_T$ was about 94.0% and the value was higher slightly than was already informed at a smooth sea state. The power for keeping up a townet speed was required more about 20% of a maximum continuous power at a rather rough sea state than a smooth sea state. In the future, if the residual resistance is considered with a sea state, $EHP_n$ will be estimated more correctly Also the data of EHP estimated by this method will be used as the basic data to design a trawl net.

• Preventive Nutrition and Food Science
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• v.18 no.2
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• pp.92-97
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• 2013

The calcification of vascular smooth muscle cells (VSMCs) is considered one of the major contributors for vascular disease. Phosphate is known as the inducer for VSMC calcification. In this study, we assessed whether phosphate affected cell viability and fetuin-A, a calcification inhibitor protein, both which are related to VSMC calcification. Also, VSMC viability by zinc level was assessed. The results showed that phosphate increased Ca and P deposition in VSMCs (A7r5 cell line, rat aorta origin). This phosphate-induced Ca and P deposition was consistent with the decreased A7r5 cell viability (P<0.05), which implies phosphate-induced calcification in A7r5 cells might be due to the decreased VSMC cell viability. As phosphate increased, the protein expression of fetuin-A protein was up-regulated. A7r5 cell viability decreased as the addition of cellular zinc level was decreased (P<0.05). The results suggested that zinc deficiency causes the decreased cell viability and it would be the future study to clarify how zinc does act for VSMC cell viability. The results suggest that the decreased VSMC viability by high P or low Zn in VSMCs may be the risk factor for vascular disease.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.472-481
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• 2006

In the conventional SRM with multi-rotor teeth, the air gap must be very small in order to drive the SRM in the saturation region that is necessary for high output torque. However, this leads to the problem of overheating; particularly in the case of a small-size SRM This paper discusses the design of a new type of SRM, namely the rolled rotor SRM. This new type does not require more than a single region of a very small airgap. This solves the overheating problem in the small size SRM. Moreover, the use of the rolled rotor, instead of the conventional toothed rotor, grades the airgap region in a fashion that gives a smooth variation in the reluctance and smooth shapes of both current and torque. The latter functional behavior is required in many applications such as servo applications. The paper first addresses general design steps of the rolled rotor SRM then proceeds to the simulation results of the new SRM in order to evaluate the advantages gained from the new design. In addition, this paper compares the torque ripples obtained from the new design to its equivalent conventional one.

• Animal cells and systems
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• v.5 no.3
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• pp.205-209
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• 2001

Mesenchymal cells from the leg buds of stage 24-chick embryos differentiated into chondrocytes when plated at high density. Treatment of high density micromass culture of chick mesenchymal cells with cytochalasin D(CD, 2 $\mu$M for 24 h) resulted in inhibition of chondrogenesis. CD treatment was found to affect the expression of the contractile protein $\alpha$-smooth muscle actin ($\alpha$-SM actin). In control cultures, $\alpha$-SM actin uniformly expressed from culture day 2, but the CD-treated cells induced expression of $\alpha$-SM actin from the first day of culture followed by a continuous increase. Expression of pan-cadherin (P-cadherin) decreased as chondrogenesis proceeded in the control culture, whereas the CD-treated cells showed sustained expression. These results propose a close connection of chondrogenic differentiation with expression of $\alpha$-SM actin and P-cadherin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.816-823
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• 2005

This paper deals with the heat exchange performance prediction of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and a micro-fin tube. The local characteristics of heat transfer, mass transfer and pressure drop are calculated using a prediction method developed by the authors. The total pressure drop and the overall heat transfer coefficient are also evaluated on various heat exchange conditions. The calculated results of the natural refrigerant mixtures are compared with HCFC22. In conclusion, natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane are appropriate candidates for alternative refrigerant from the viewpoint of heat transfer characteristics.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.256-261
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• 2005

In the present experimental study, condensation heat transfer coefficients between R404A and R152a flow in a horizontal smooth tube were compared. The outer and inner diameters of the tube were 9.52 mm and 7.55 mm, respectively, and the heated length was 1045 mm. The mass flux ranged from 150 to 400 $kg/m^{2}s$ and the test section were uniformly heated from 8 to 12. $kW/m^2$. The quality range was from 0.2 to 0.8 at the saturation temperature from 27.3 to $34^{\circ}C$. Experimental condensation heat transfer coefficients increased as the quality and mass flux increased. Modified Dobson and Chato correlation reduced the mean deviation of 5.1% for R404A and 9.4% for R152a than the original correlation$^{(2)}$.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.447-459
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• 2012

The present study numerically investigates the effect of the wavy leading edge on hydrodynamic characteristics for the flow of rectangular wings with the low aspect ratio of 1.5. Five different wave lengths at fixed wavy amplitude have been considered. Numerical simulations are performed at a wide range of the angle of attack ($0^{\circ}{\leq}{\alpha}{\leq}40^{\circ}$) at one Reynolds number of $10^6$. The wavy wings considered in this study did not experience enough lift drop to be defined as the stall, comparing with the smooth wing. However, in the pre-stall region, the wavy wings reveal the considerable loss of the lift, compared to the smooth wing. In the post-stall, the lift coefficients of the smooth wing and the wavy wings are not much different. The pressure coefficient, limiting streamlines and the iso-surface of the spanwise vorticity are also highlighted to examine the effect of the wave length on the flow structures.