• The Korean Journal of Physiology and Pharmacology
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• 제27권5호
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• pp.481-491
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• 2023

The β subunits of high voltage-gated calcium channels (HGCCs) are essential for optimal channel functions such as channel gating, activation-inactivation kinetics, and trafficking to the membrane. In this study, we report for the first time the potent blood pressure-reducing effects of peptide fragments derived from the β subunits in anesthetized and non-anesthetized rats. Intravenous administration of 16-mer peptide fragments derived from the interacting regions of the β1 [cacb1(344-359)], β2 [cacb2(392-407)], β3 [cacb3(292-307)], and β4 [cacb4(333-348)] subunits with the main α-subunit of HGCC decreased arterial blood pressure in a dose-dependent manner for 5-8 min in anesthetized rats. In contrast, the peptides had no effect on the peak amplitudes of voltage-activated Ca²⁺ current upon their intracellular application into the acutely isolated trigeminal ganglion neurons. Further, a single mutated peptide of cacb1(344-359)-cacb1(344-359)_K357R-showed consistent and potent effects and was crippled by a two-amino acid-truncation at the N-terminal or C-terminal end. By conjugating palmitic acid with the second amino acid (lysine) of cacb1(344-359)_K357R (named K2-palm), we extended the blood pressure reduction to several hours without losing potency. This prolonged effect on the arterial blood pressure was also observed in non-anesthetized rats. On the other hand, the intrathecal administration of acetylated and amidated cacb1(344-359)_K357R peptide did not change acute nociceptive responses induced by the intradermal formalin injection in the plantar surface of rat hindpaw. Overall, these findings will be useful for developing antihypertensives.

• 한국의류학회지
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• 제45권3호
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• pp.495-509
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• 2021

The study investigated the effects of five commercial body shaping foundation items on clothing pressure, blood flow, body shaping effectiveness, and wearer satisfaction for middle-aged women. The study measured clothing pressure at each of the 10 designated measurement points for twelve subjects wearing the foundations. Blood flow changes were recorded and body shaping effectiveness was analyzed by comparing differences in girth when wearing and not wearing the foundations. The subjects rated wearer comfort along a 7-point Likert scale. The results were that clothing pressure was present at all measurement points, and all foundations placed the least pressure on the anterior underbust girth. In addition, clothing pressure was high in the order of the lateral, posterior, and anterior areas. As clothing pressure increased, blood flow and velocity decreased and overall wearer satisfaction was assessed to be less comfortable. Body shaping effectiveness was evident across all the items, as all decreased girth measurements significantly. In conclusion, the appropriate level of clothing pressure provided by experimental foundations which is positive for blood flow and has an excellent body shaping effect was found to be between 0.53 and 1.77 kPa.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1511-1514
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• 2009

Liquid whole egg (LWE) was subjected to high hydrostatic pressure (HHP), a consecutive combination of nisin and HHP (nisin-HHP), or a consecutive combination of ultrasound and HHP (ultrasound-HHP), and functional properties of processed LWE were compared to those of raw LWE. Little changes in foaming and emulsifying properties were observed by the application of HHP alone and the combined process of nisin and HHP. In contrast, ultrasound-HHP combination resulted in significant changes in color, foaming, and emulsifying properties. The maintenance of functional properties after HHP treatment agreed with expectation, because the HHP processing condition had been selected where minimal rheological changes had occurred.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.115-116
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• 2002

This study was carried out as one of efforts to overcome difficulties in air bearing design due to low stiffness and low damping. Hydrodynamic effects on hydrodynamic stiffness of a fluid film in a high speed air bearing with tow-row air sources are investigated. The hydrodynamic effects by the high speed over DN 1,000,000 and eccentricity of a proceeding which are not considered in conventional design of an air bearing need to be reconsidered. The hydrodynamic effects, which dominantly influence on the load capacity of air bearing, are caused mainly by proceeding speed, eccentricity, and the source positions. The two-row source arrangement in the air bearing produces quite unique hydrodynamic effects with respect to pressure distribution of the air film. Optimal arrangement of the two-row sources improves performance of an air bearing in film reaction force and loading capacity of high speed spindles. This study compares the pressure distribution by numerical simulation as a function of eccentricity of proceeding and the source positions. The air source position 1/7L form one end of an air bearing was found to be superior to source position of 1/4L. The dynamic stiffness were obtained using a two-dimensional cutting method which can directly measure the cutting reaction forces and the displacements of the spindle in two directions using a tool dynamometer and transducer sensors. Heat generation in the air film can not be negligible over the speed of DN 2,000,000. In order to analysis effects of heat generation on the characteristics of air bearing, high cooling bearing spindle and low cooling bearing spindle were tested and compared. Characteristics of the frequency response of shaft and motion of run out errors were different for the spindle. The test results show that, in the case of low cooling bearing spindle, the stiffness became smaller due to heat generation. The results, which were obtained for high speed region, may be used as a design information for spindle which can be applied to precision devices such as ultra precision grinding and ultra high speed milling.

• Tribology and Lubricants
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• 제17권5호
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• pp.365-372
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, The pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.279-283
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• 2002

The effects of finite gap at the tip of turbomachinery blades have long been topics of both theoretical and experimental research because tip clearance degrades turbomachinery performance. This paper presents an analytical study of radial flow redistribution in a high speed compressor stage with axisymmetric tip clearance. The flow is assumed to be inviscid and compressible. The stage is modeled as an actuator disc and the analysis is carried out in the meridional plane. Upon going through the stage, the radially uniform upstream flow splits into the tip clearance and passage flows. The tip clearance flow is modeled as a jet driven by blade loading, or pressure difference between the pressure and suction sides. The model takes into consideration the detached shocks which occur in the rotor passage at the design point. This shock model is used to calculate the density ratio across the stage. Thus, the model is capable of predicting the kinematic effects of tip clearance in the high speed compressor flow field.

• Tribology and Lubricants
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• 제17권6호
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• pp.476-481
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, The pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The theoretical analysis have been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 설비공학논문집
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• 제18권12호
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• pp.1039-1046
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• 2006

The numerical simulations on the train entering a tunnel are performed by solving unsteady axi-symmetric problems. To reduce the effects of the pressure wave generated by the train starting abruptly, several starting methods of the train are examined. The high order velocity increase gives better results than those for the linear velocity increase. The high order velocity increase gives good results for the pressure rise by the train entering a tunnel, too. The distance to the train reaches the highest running velocity from the start should be more than 60 m when the train speed is 350 km/h.

• 한국축산식품학회지
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• 제34권1호
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• pp.14-19
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• 2014

This study investigated the effects of protease treatments (trypsin, chymotrypsin, and pepsin) under various pressure levels (0.1-300 MPa) for the characteristics of porcine placenta hydrolysates. According to gel electrophoretic patterns, the trypsin showed the best placental hydrolyzing activity followed by chymotrypsin, regardless of the pressure levels. In particular, the peptide bands of tryptic-digested hydrolysate were not shown regardless of applied pressure levels. The peptide bands of hydrolysate treated chymotrypsin showed gradual decreases in molecular weights ($M_w$) with increasing pressure levels. However, the pepsin did not show any evidences of placental hydrolysis even though the pressure levels were increased to 300 MPa. The gel permeation chromatography (GPC) profiles showed that the trypsin and pepsin had better placental hydrolyzing activities under high pressure (particularly at 200 MPa), with lower $M_w$ distributions of the hydrolysates. Pepsin also tend to lower the $M_w$ of peptides, while the major bands of hydrolysates being treated at 300 MPa were observed at more than 7,000 Da. There were some differences in amino acid compositions of the hydrolysates, nevertheless, the peptides were mainly composed of glycine (Gly), alanine (Ala), hydroxyproline (Hyp) and proline (Pro). Consequently, the results indicate that high pressure could enhance the placental hydrolyzing activities of the selected proteases and the optimum pressure levels at which the maximum protease activity is around 200 MPa.

• 한국철도학회논문집
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• 제12권6호
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• pp.961-966
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• 2009

고속 철도 건설시, 선로중심 간격 및 시공기면폭의 감소는 건설 비용의 절감을 가져온다. 그러나, 선로중심간격의 축소는 열차 주행 풍압의 증가로 여러 가지 안전성 문제를 야기 할 수 있으므로 기술적 검토와 공기 역학적 연구가 수행되어야 한다. 본 연구에서는 호남고속철도에 적합한 선로 중심 간격을 검토하는데 필요한 차량 주행 안전성을 해석하기 위하여 선로중심 간격 변화로 인한 교행 열차 풍압을 예측하였으며, 차량 전복 안전성에 끼치는 열차 풍압의 영향에 대한 파라메타 연구를 하였다.