• Journal of computational fluids engineering
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• v.9 no.3
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• pp.66-72
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• 2004

전도 열전달 분야에서 두 물체가 접해 있는 경우, 접촉 열저항은 고려해야 할 중요한 요소이다. 특히 최근에는 전자부품의 과열방지를 위한 열 소산과 관련하여 접촉 열저항 문제는 중요하게 대두되고 있으며 이에 관련한 많은 이론적 연구와 응용연구가 수행되고 있다. 접촉 열저항은 주로 거친 두 물체표면의 불완전접촉에 기인한다. 본 연구에서는, 접촉하는 두 물체사이의 접촉면을 이상화시킨 비교적 간단한 문제를 이론적으로 해석함으로써 접촉면의 틈새 형상 및 비접촉면적비(비접촉면적/외관접촉면적)의 크기에 따른 접촉 열저항의 크기를 구하였다.

• Wind and Structures
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• v.12 no.1
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• pp.49-61
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• 2009

A method is presented to estimate the form drag and the base pressure on a triangular cylinder in the presence of blockage effect. The Strouhal number, which is found to increase with the flow constriction experimentally by Ramamurthy & Ng (1973), may be decoupled from the blockage effect when re-defined by using the velocity at flow separation and a theoretical wake width. By incorporating this wake width into the momentum equation by Maskell (1963) for the confined flow, a relationship between the form drag and the base pressure is derived. Independently, the experimental data of surface pressure from Ramamurthy & Lee (1973) are found to be independent of the blockage effect when expressed in terms of a modified pressure coefficient involving the pressure at separation. Using the potential flow model by Parkinson & Jandali (1970) and its subsequent development in Yeung & Parkinson (2000) for the unconfined flow, a linear relation between the pressure at separation and the form drag is formulated. By solving the two equations simultaneously with a specified blockage ratio and an apex angle of the triangular cylinder, the predictions of the drag and the base pressure are in reasonable agreement with experimental data. A new theoretical relationship for the Strouhal number, pressure drag coefficient and base pressure proposed in this study allows the confinement effect to be appropriately taken into consideration. The present approach may be extended to three-dimensional bluff bodies.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.591-596
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• 2000

Flow through compliant tubes with linear taper in wall thickness is numerically simulated by finite element analysis. Two models are examined: a planar two-dimensional channel, and an axisymmetric tube. For verification of the numerical method, flow through a compliant stenotic vessel is simulated and compared to existing experimental data. Computational results for an axisymmetric tube show that as cross-sectional area falls with a reduction in downstream pressure, flow rate increases and reaches a maximum when the speed index (mean velocity divided by wave speed) is near unity at the point of minimum cross-section area, indicative of wave speed flow limitation or "choking" (flow speed equals wave speed) in previous one-dimensional studies. For further reductions in downstream pressure, flow rate decreases. Cross-sectional narrowing is significant but localized. When the ratio of downstream-to-upstream wall thickness is ${\le}$ 2 the area throat is located near the downstream end; as wall taper is increased to ${\ge}$ 3 the constriction moves to the upstream end of the tube. In the planar two-dimensional channel, area reduction and flow limitation are also observed when outlet pressure is decreased. In contrast to the axisymmetric case, however, the elastic wall in the two-dimensional channel forms a smooth concave surface with the area throat located near the mid-point of the elastic wall. Though flow rate reaches a maximum and then falls, the flow does not appear to be choked.

• Archives of Craniofacial Surgery
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• v.22 no.2
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• pp.85-92
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• 2021

Background: Patients with secondary deformities associated with unilateral cleft lip and nose might also suffer from nostril stenosis due to a lack of tissue volume in the nostril on the cleft side. Here, we used full-thickness skin grafts (FTSGs) to reduce nostril stenosis and various methods for skin volume augmentation. We compared the changes in the symmetry of both nostrils before and after surgery. Methods: From February 2016 to January 2020, 34 patients underwent secondary cheiloplasty and open rhinoplasty for secondary deformities of the unilateral cleft lip and nose with nostril stenosis. FTSG was used on the nostril floor, nasal columella, and alar inner lining. The measured nasal profile included the nostril surface, nostril circumference, width of the nostril floor, and distance from the alar-facial groove to the nasal tip. The "overlap area," which was defined as the largest overlapping area when the image of the cleft nostril was flipped to the left and right and overlaid on the image of the normal side nostril, was also calculated. The degree of symmetry was evaluated by dividing the value of the cleft side by that of the normal side of each measured profile and expressed as "ratios." Results: The results of all profile ratios, except for the nostril floor width, became significantly close to 1, which represents full symmetry. The overlap area ratio improved from 62.7% to 77.3%, meaning that the length and width of the nostril as well as the overall shape became similar (p< 0.05). Conclusion: When performing cleft rhinoplasty with nostril stenosis, FTSG is useful to achieve symmetry in the nostril size and shape. Skin grafting is simpler to perform than the other types of local flap, and the results are generally satisfactory.

• Journal of Chest Surgery
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• v.34 no.9
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• pp.662-671
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• 2001

Background: This study was aimed to assess improvement in myocardial perfusion after TMR by measuring regional myocardial blood flow(RMBF) in porcine model of chronic myocardial ischemia. Material and Method: Ameroid ring was placed around the proximal left circumflex coronary artery in fourteen pigs. After 4 weeks, the control group(7 pigs) underwent rethoracotomy only, and the TMR group(7 pigs) underwent Ho:YAG laser TMR at the circumflex territory. After another 4 weeks, the animals were sacrificed for the measurement of RMBF using colored microspheres. The ratio of RMBF between the circumflex territory and the interventricular septum was calculated and compared. Result: At 4 weeks after ameroid constriction, RMBF of the circumflex territory decreased to 46∼89% of RMBF of the interventricular septum. In five of six animals in the TMR group, RMBF of the circumflex territory at 8 weeks after ameroid constriction was higher compared with RMBF at 4 weeks after ameroid constriction. However, the improvement was statistically significant only in two animals. In three of the four animals in the control group, RMBF of the circumflex territory also increased at 8 weeks compared with RMBF at 4 weeks. The degree of increase in RMBF was not different between the control and the TMR groups. Conclusion: In porcine model of chronic myocardial ischemia, the degree of increase in RMBF of the ischemic area after Ho:YAG TMR was not different from the increase by development of native collateral circulation. Perfusion of ischemic myocardium after TMR is not thought to improve to the degree that can be demonstrated by currently available method of assessment such as radioisotope myocardial scintigraphy.

• Radiation Oncology Journal
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• v.16 no.3
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• pp.325-335
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• 1998

Purpose : Since the mid cranial fossa is composed of various thickness of bone, the tissue inhomogeneity caused by bone would produce dose attenuation in cobalt-60 gamma knife irradiation. The correction factor for bone attenuation of cobalt-60 which is used for gamma knife source is -3.5$\%$. More importantly, nearly all the radiosurgery treatment planning systems assume a treatment volume of unit density: any perturbation due to tissue inhomogeneity is neglected, This study was performed to confirm the bone attenuation in mid cranial fossa using gamma knife. Materials and Methods : Computed tomography was performed after Leksell stereotactic frame had been liked to the Alderson Rando Phantom (human phantom) skull area. Kodak X-omat V film was inserted into two sites of pituitary adenoma point and acoustic neurinoma point, and irradiated by gamma knife with 14mm and 18mm collimator. An automatic scanning densitometer with a 1mm aperture is used to measure the dose profile along the x and y axis. Results : Isodose curve constriction in mid cranial fossa is observed with various ranges. Pituitary tumor point is greater than acoustic neurinoma point (0.2-3.0 mm vs 0.1-1.3 mm) and generally 14 mm collimator is greater than 18mm collimator (0.4-3.0 mm vs. 0.2-2.2 mm) Even though the isodose constriction is found, constriction of 50$\%$ isodose curve which is used for treatment reference line does not exceed 1 mm. This range is too small to influence the treatment planning and treatment results. Conclusion : Radiosurgery planning system of gamma knife does not show significant error to be corrected without consideration of bone attenuation.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.360-363
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• 2000

Deformation in the hysteresis loop of $Pb(Zr,Ti)O_3$ (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.

• Journal of Oriental Neuropsychiatry
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• v.17 no.2
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• pp.133-145
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• 2006

Objective : The purpose of this experimental-controlled study was to investigate the characteristics of the autonomic nervous system in students with Keongke by using HRV(Heart rate variability) and PSV(Pupil size variability). Method : The study group was consisted of 11 students with self recognition as the experimental group, and 25 normal students as the control group. Informations on gender and age were obtained by medical charts and personal interviews. By using heart rate variability and pupil size variability, we measured the value of HRT(Heart rate), SDNN(Standard deviation of NN intervals), LFnorm(Low frequency normalization), HFnorm(High frequency normalization), LF/HF ratio, Pupil area, B.S.(Basic size), C.R.(Max Constriction Rate) and 1s.d.(1sec Dilation Rate). I compared the degrees of the sympathetic and parasympathetic activity. Result : 1. In the result of heart rate variability between experimental and control group, none of the parameters of experimental group were significantly different from control group. And even though there were no statistical significance, there were some numerical differences in SDNN, LF norm, HF norm. 2. In pupil size variability, C.R. and 1s.d. of the experimental group were increased compared to control group. Conclusion : The study results suggest that the group with Keongke has differences of autonomic nervous system as compared to those in normal state. Measurement value of PSV is a new technical approach to estimate the autonomic nervous system.

• Food Science of Animal Resources
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• v.22 no.1
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• pp.87-93
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• 2002

Angiotensiri-I converting enzyme(ACE) catalyst the removal of the C-terminal dipeptide from the angiotensin-I to give the angiotensin-II, a potent peptide that causes constriction of regulation of blood pressure. Recently, ACE inhibitor peptides have been isolated from enzymatic digests of food protein. The aim of this study was to identify bovine casein hydrolysates with ACE inhibitory properties in different enzymatic hydrolysis conditions. The casein were hydrolyzed neutrase, alcalase, protamax, flavourzyme, premed 192, sumizyme MP, sumizyme LP and pescalase alone and with an enzyme combination. Premed 192 produced ACE inhibitory peptides most efficiently. In order to ACE inhibitory peptide produced enzymatic hydrolysis condition were premed 192 added to casein ratio of 1:100(w/w), and incubated at 47$\^{C}$ for 12hrs. Casein hydrolysate gave 50% inhibition(IC$\_$50/ value) of ACE activity at concentration with 248ug/ml(general method) and 265ug/ml(pretreatment method) respectively.

• Journal of Acupuncture Research
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• v.32 no.2
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• pp.131-145
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• 2015

Objectives : The purpose of this study was to demonstrate the effectiveness and availability of salt pharmacopuncture of Korean sun-dried salt and processing salt on the basis of bibliographical review. Methods : This study was done through a narrative review of related bibliography including medical books, journals, general bibliography, and web sites. Results : 1. Korean sun-dried salt is produced in the ground with soil, tiles, and pottery. Sun-dried, traditional, granulated, bamboo, and grilled salts are all appropriate for medical use. They are composed of a lower level of NaCl and unnecessary substances, and have a higher water and mineral content. 2. The 9~30 g of NaCl included in the physiological saline matches the ratio of a normal human body. However, if the saline is used for water supply, it should be improved because the recommended amount is much lower. 3. Medicine that includes NaCl is applied for lessening the congestion of the nasal cavity, alleviating cornea swelling, or for a lack of water. NaCl can also be used for washing contact lenses as well as cleaning the mucous membrane of the eyes and nose. 4. Salt relieves anger, detoxifies, induces vomiting, builds strong muscles and bones, gives energy, slows aging, and ultimately improves health. 5. Salt treats many diseases including: cardiovascular, hematosis, respirometer, obstetric, musculoskeletal, mineral supplement, eye, teeth and skin issues, etc.. However, salt is not used for treating asthma, cough, or other ailments mainly affecting the vascular system. 6. While NaCl in salt absorbs water and the vascular constriction results in higher blood pressure, the pressure induced from salt is actually a physiologically temporary rise. Rather, salt helps remove oil from the body and its potassium lowers blood pressure. Conclusions : It was suggested that salt pharmacopuncture of Korean sun-dried salt and processing salt should be made available for adjusting the physiological salt concentration and control of the Na side effects, therefore it would be useful in the treatment of diseases.