• Journal of Magnetics
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• v.22 no.2
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• pp.181-187
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• 2017

Flow of electrically conducting nanofluids is of pivotal importance in countless industrial and medical appliances. Fluctuations in thermophysical properties of such fluids due to variations in temperature have not received due attention in the available literature. Present investigation aims to fill this void by analyzing the flow of copper-water nanofluid with temperature dependent viscosity past a Riga plate. Strong wall suction and viscous dissipation have also been taken into account. Numerical solutions for the resulting nonlinear system have been obtained. Results are presented in the graphical and tabular format in order to facilitate the physical analysis. An estimated expression for skin friction coefficient and Nusselt number are obtained by performing linear regression on numerical data for embedded parameters. Results indicate that the temperature dependent viscosity alters the velocity as well as the temperature of the nanofluid and is of considerable importance in the processes where high accuracy is desired. Addition of copper nanoparticles makes the momentum boundary layer thinner whereas viscosity parameter does not affect the boundary layer thickness. Moreover, the regression expressions indicate that magnitude of rate of change in effective skin friction coefficient and Nusselt number with respect to nanoparticles volume fraction is prominent when compared with the rate of change with variable viscosity parameter and modified Hartmann number.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.65.1-65.1
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• 2011

We built a simple Adaptive Optics (AO) system at laboratory. This AO system is a step toward developing AO system for astronomical use. In this step, the AO system consists of He-Ne laser as a artificial light source, wavefront sensor, MEMS (Micro electro mechanical system) type deformable mirror and several lenses. MEMS deformable mirror allows the compact system at low cost and the only several mm sized collimated beam. We made Shack-Hartmann wavefront sensor using a lenslet array and a fast frame CCD. Its performance is verified using an artificial phase disturber and noting the movement of spot images by the lenslet array. The frame rate of the driving software is about 70 fps, depending on the control parameters. The characteristics of MEMS deformable mirror was measured which includes the voltage-to-deflection relation, influence function, and cross-talk. The total system is operated under closed-loop control for the artificial phase disturber and the wavefront is found to be compensated successfully.

• Smart Structures and Systems
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• v.12 no.2
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• pp.209-233
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• 2013

With an annual growth rate of about 30%, wind energy systems, such as wind turbines, represent one of the fastest growing renewable energy technologies. Continuous structural health monitoring of wind turbines can help improving structural reliability and facilitating optimal decisions with respect to maintenance and operation at minimum associated life-cycle costs. This paper presents an integrated monitoring system that is designed to support structural assessment and life-cycle management of wind turbines. The monitoring system systematically integrates a wide variety of hardware and software modules, including sensors and computer systems for automated data acquisition, data analysis and data archival, a multiagent-based system for self-diagnosis of sensor malfunctions, a model updating and damage detection framework for structural assessment, and a management module for monitoring the structural condition and the operational efficiency of the wind turbine. The monitoring system has been installed on a 500 kW wind turbine located in Germany. Since its initial deployment in 2009, the system automatically collects and processes structural, environmental, and operational wind turbine data. The results demonstrate the potential of the proposed approach not only to ensure continuous safety of the structures, but also to enable cost-efficient maintenance and operation of wind turbines.

• Current Optics and Photonics
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• v.8 no.1
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• pp.30-37
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• 2024

Implemented at the Geochang Observatory in South Korea, our slope detection and ranging (SLO-DAR) system features a 508 mm Cassegrain telescope (f /7.8), incorporating two Shack-Hartmann wave-front sensors (WFS) for precise measurements of atmospheric phase distortions, particularly from nearby binary or double stars, utilizing an 8 × 8 grid of sampling points. With an ability to reconstruct eight-layer vertical atmospheric profiles, the system quantifies the refractive index structure function (C_n²) through the crossed-beam method. Adaptable in vertical profiling altitude, ranging from a few hundred meters to several kilometers, contingent on the separation angle of binary stars, the system operates in both wide (2.5 to 12.5 arcminute separation angle) and narrow modes (11 to 15 arcsecond separation angle), covering altitudes from 122.3 to 611.5 meters and 6.1 to 8.3 kilometers, respectively. Initial measurements at the Geochang Observatory indicated C_n² values up to 181.7 meters with a Fried parameter (r₀) of 8.4 centimeters in wide mode and up to 7.8 kilometers with an r₀ of 8.0 centimeters in narrow mode, suggesting similar seeing conditions to the Bohyun Observatory and aligning with a comparable 2014-2015 seeing profiling campaign in South Korea.

• Journal of Families and Better Life
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• v.5 no.2
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• pp.45-64
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• 1987

In this study the phenomenon of commodity substitution of housework is approach in the contexts of economic system, patriachal family system and housework-related human resources. the objectives of this study are as follows: (1) To measure the level of commodity substitution of housework in large cities. (2)To investigate the factors influencing commodity substitution of housework. The samples were composed of 982 housewives dwelling in 6 large cities including Seoul. The statistics used for data analysis were frequency distribution, percetile. multiple regression analysis. The major findings are the following; (1) When the housework was divided into two subdomains , in the domain of food the purchase level was for below average while in the domain of clothes, the level was quite higher than average. This result hows that commodity substitution has become more common in the domain of clothes by mass production of clothes on a commercial scale. (2) the level of commodity substitution of housework was influenced by the family attribute variables such as housewife's age, family income. housewife's education, family types, housewife's brought-up regions, presence of sewing machine, employment status of housewife, by one patriarchal norm variable such as home-orientedness, and by tow human resource variables such as importance of housework and household tasks performance competnecy. Among variables house wife's age was the most influential one and such variables as family income, housewife's education, household task performance competency, importance of housework, and home-orientedness were also important. Considering that the influence of home-orientedness demonstrates the importance of patriarchy and that importance of housework and that performance competency also are determined by the patriarchal variables such as sex-role attitude and home-orientedness, we can conclude that Hartmann's theoretical approach with which the changes of housework were explained in the two contexts of economic system and family system is applied to the changes of housework in Korea.

• Journal of Chest Surgery
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• v.10 no.2
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• pp.299-314
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• 1977

Clinical experience on 16 cases of open heart surgery under the extracorporeal circulation with mild or moderate hypothermia and partial hemodilution technique at the National Medical Center during the period from June 1976 to October 1977. Nine of sixteen were congenital heart disease and seven were acquired heart disease. The age of the patient ranged between 6 and 48 years. The body weight varied from 18.5kg to 60kg and body surface area 0. 79-1.70m2. The average priming volume of pump oxygenator was 2080 ml, which was consisted fresh ACD blood, buffered Hartmann`s solution, Mannitol, 50% dextrose in water and Vit. C. The average hemodilution rate was 27%. The average flow 2.3 L/min/m2 or 80 ml/min and the duration of perfusion varied from 31 min to 270 min with average of 107 min. The perfusion was carried out under the mild or moderate hypothermia using core cooling alone in 10 cases, core cooling and local myocardial cooling with $0-4^{\circ}C$ physiologic saline in 2 cases. From a hemodynamic point of view, the blood pressure dropped down around 80 mmHg after the initiation of perfusion follwed by increase to safety level and stable during the perfusion. The central venous pressure remained within normal limits. In most cases, hemoglobin and hematocrit decreased during and after the perfusion. Hemogiobin level was decreased, average of 20.6 %, hematocrit 18.6%, pletelets 55% postoperatively. Plasma hemoglobin increased moderately, from preperfusion average valve of 7.79 mg % to post-perfusion value of 54.7 mg %. Electrolytes changes during cardiopulmonary bypass showed definite hypokalemia but changes of Na, Ca were not definite. Arterial blood gas analysis during cardiopulmonary bypass suggested that the metabolic acidosis which was accompanied by respiratory alkalosis which was corrected postoperatively. As the opera tive complication, transient hemoglobinuria in 4 cases and neurological signs in 2 cases were all cured. There were 2 death cases and operative mortality rate was 12.5%.

• Advances in Computational Design
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• v.3 no.4
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• pp.339-366
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• 2018

Parametric design systems serve as powerful assistive tools in the design process by providing a flexible approach for the generation of a vast number of design alternatives. However, contemporary parametric design systems focus primarily on low-level engineering and structural forms, without an explicit means to also take into account high-level, cognitively motivated people-centred design goals. We present a precedent-based parametric design method that integrates people-centred design "precedents" rooted in empirical evidence directly within state of the art parametric design systems. As a use-case, we illustrate the general method in the context of an empirical study focusing on the multi-modal analysis of wayfinding behaviour in two large-scale healthcare environments. With this use-case, we demonstrate the manner in which: (1). a range of empirically established design precedents -e.g., pertaining to visibility and navigation- may be articulated as design constraints to be embedded directly within state of the art parametric design tools (e.g., Grasshopper); and (2). embedded design precedents lead to the (parametric) generation of a number of morphologies that satisfy people-centred design criteria (in this case, pertaining to wayfinding). Our research presents an exemplar for the integration of cognitively motivated design goals with parametric design-space exploration methods. We posit that this opens-up a range of technological challenges for the engineering and development of next-generation computer aided architecture design systems.

• Journal of Yeungnam Medical Science
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• v.32 no.1
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• pp.31-34
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• 2015

In Korea, cases of direct insertion of foreign bodies into the rectum are rare in the literature. Most cases of rectal insertion of foreign bodies are associated with sexual acts and psychiatric disorder such as schizophrenia. Objects inserted into the anus are usually blunt and shaped like the male genitalia. The removal method can be varied depending on the size and shape of the foreign object, its anatomical location, and the accompanying complications. In cases wherein attempts to remove the object fail or there are rectal perforation and peritonitis complications, immediate laparotomy may be required in order to prevent serious complications such as sepsis. Here, we report on a case of rectal perforation and peritonitis due to insertion of a foreign body in a middle-aged patient, with a literature review. He inserted a sharp pig backbone in his rectum and he only had depression. The patient underwent a Hartmann's operation as well as psychiatric counseling and treatment. Thus, after removal of foreign bodies, psychiatric counseling and treatment should be carried out in order to prevent similar accidents and to minimize the need for trauma medicine.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.179-190
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• 1989

The experimental study for extracorporeal preservation of the heart-lung preparation by autoperfusion system was performed in 10 dogs. Under intravenous Pentothal endotracheal anesthesia bilateral thoracotomies were performed. A 24F cannula connected to a plastic reservoir bag located 100 cm above the level of the heart was introduced into the aortic arch. Left subclavian, innominate artery, and descending aorta were ligated and divided. Both vena cavae were ligated and divided after the bag was half filled with blood. A 24F catheter inserted into right atrium and connected to the plastic bag in order to keep constant the preload. The thoracic trachea was intubated and the lungs were ventilated. The heart-lung preparations were removed en bloc and floated in a $34^{\circ}C$ bath of Hartmann solution. The preparations were observed for from 2 hours to 8 hours, with the average of 5.2 hours. Hemodynamic and hematologic variables were measured during preharvest and autoperfusion. The pH revealed severe respiratory alkalosis due to very low $PaCO_2$ during autoperfusion ; $PaO_2$ remained constant for 130-140 mmHg; $A-aDO_2$ increased markedly. The static inspiratory pressure [SIP] at late autoperfusion [6hr] increased significantly as compared with at early autoperfusion [2hr]. There was no difference between white blood cell counts from right atrium and those of left atrium. Heart rates remained constant for 110-120/min; cardiac outputs maintained to approximately 0.6L/min; mean aortic pressures, 75 mmHg; mean pulmonary arterial pressures, 15-18 mmHg; mean right atrial pressures, 9-13 mmHg; mean left atrial pressures, 12 mmHg lower than those of right atrium. Serum Na maintained with normal range during autoperfusion; K increased significantly; Ca decreased progressively. Hemoglobin and hematocrit decreased significantly during autoperfusion. The study demonstrated that stable hemodynamics could be maintained throughout the experiment and the preparation of the lung seemed to be inadequate, especially after 3-4 hours, such as high $A-aDO_2$, increased SIP, and scattered atelectasis and edema in their gross appearances.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.2
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• pp.102-105
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• 2016

Objective: The goal of this study was to compare the semen parameters of two successive samples obtained within an interval of less than 60 minutes from patients planning to undergo intrauterine insemination (IUI) whose first samples exhibited low semen quality. Methods: Thirty-two consecutive patients were enrolled in the study. On the day of IUI, the semen analysis of the samples initially presented by all patients met at least two of the following criteria: sperm concentration $<5{\times}10^6/mL$, total sperm count $<10{\times}10^6$, progressive sperm motility (a+b) in the native sample <30%, and total motile sperm count (TMSC) $<4{\times}10^6$. A successive semen sample was obtained no more than 60 minutes after the first sample. Results: Compared to the first sample, the second exhibited significantly (p<0.05) improved sperm concentration, TMSC, progressive motility, and vitality. Regarding TMSC, the most critical parameter on the day of IUI, 23 patients (71.8%) improved it, while nine (28.2%) displayed poorer outcomes. Conclusion: In defined cases, requesting a second successive ejaculate on the day of insemination may result in a high percentage of cases in an improvement of the quality of the sample.