• Journal of the Korean Institute of Educational Facilities
• /
• v.18 no.5
• /
• pp.16-19
• /
• 2011

• Journal of the Korean Institute of Educational Facilities
• /
• v.20 no.5
• /
• pp.42-45
• /
• 2013

• International Journal of Fluid Machinery and Systems
• /
• v.5 no.4
• /
• pp.161-167
• /
• 2012

Small-sized axial fans are used as air coolers for electric equipment. There is a strong demand for higher power of fans according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is conducted, although, it causes the deterioration of the efficiency and the increase of noise. Then, the adoption of contra-rotating rotors for small-sized fans is proposed for the improvement of the performance. In the case of contra-rotating rotors, blade row distance between the front and the rear rotors influences on the performance and the noise. Therefore, it is important to clarify the optimum blade row distance between front and rear rotors. The performance curves of the contra-rotating small-sized axial fan under the condition of different blade row distances are shown and the blade row interaction between the front and the rear rotors are discussed by the numerical results. Furthermore, the optimum blade row distance of the contra-rotating small-sized axial fan is considered.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.10
• /
• pp.4853-4862
• /
• 2012

In Modern Cities, The 'Cultural spaces or facilities' are the core of the urban activity. And it is the field of urban life which can improve the quality of life and change the human's life style. Also in Contemporary society, Cultural spaces are required to express the social and psychological activity of the city life and the diversity and function of human beings. But most of them are located in the Metropolitan area. In these days, the needs of cultural spaces and facilities in 'Medium sized-cities' are growing. And many development plans are working in practice in that cities to accede to these requirements of social, human and current of the times. They include the exhibition spaces which perform function of the field of art and culture, that have powerful and infinite potentiality of the social development. At this Point, this study suggest that 'Optimum level' of exhibition spaces as Museum and Art-gallery in Medium sized-cities. To achieve this study, two phases are proceeded as follows. First, Check the social needs of it based on theoretical inquiry of Exhibition space. Second, Focused on Medium sized-cities, through a comparison between 12 Domestic cities and 4 Japan's cities. A population of their cities is from 500,000 to 1,000,000. We can get a data for Optimum level of Exhibition space. And last, Suggest the strategies of the location and planning of Exhibition space based on Second phase.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.364-369
• /
• 2007

A system heat pump provides the benefits of comfort, energy conservation and easy maintenance. Recently, the system heat pump has been employed in small and medium-sized buildings. However, the performance data and control algorithm for system heat pump are limited in literature due to complicated system parameters and operating conditions. In the present study, the performance of a system heat pump with two indoor unit is measured by varying indoor loads, EEV opening, and compressor speed. In addition, the integral optimum regulator which includes MIMO control algorithm is proposed. The capacity modulation and optimum capacity for each indoor unit can be adjusted by utilizing the EEVs opening and compressor speed. The proposed scheme shows appropriate control performance at test conditions.

• Journal of Hydrogen and New Energy
• /
• v.20 no.4
• /
• pp.323-330
• /
• 2009

Efficiency of a fuel cell is determined by the generated water. If water is not removed sufficiently, water will be accumulated at GDL, which causes flooding. Therefore, water control is regarded as a crucial factor to sustain fuel ell performance. In this study, PTFE coating on the surface of carbon paper was carried out to establish optimum process for hydrophobic treatment of GDL. Carbon paper was immersed at different concentrations of nano-sized PTFE coating solution. Their characteristics were analyzed systematically by FE-SEM, water contact angle, cyclic voltamogam, XRD and FT-IR. The quantitative correlation between the amount of coated-PTFE on a carbon paper and concentration of coating solution was carefully investigated. It is suggested that the amount of PTFE-coating on a carbon paper can be managed by means of controling concentration of coating solution.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.11 no.3
• /
• pp.132-139
• /
• 2003

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-sized centrifugal compressor are investigated. Especially, numerical analyses are conducted for the centrifugal compressor with both a circular casing and a volute one. The optimum design for each element (i.e., impeller, diffuser and casing) is important to develop an efficient and compact compressor using alternative refrigerant as working fluids. Typical rotating speed of the compressor is in the range of 40,000∼45,000 rpm. The impeller has backswept blades due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside an entire impeller, vaneless diffuser and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For computations of compressible turbulent flow fields, the continuity and time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained for various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. The static pressure around the casing and pressure difference between the inlet and outlet of the compressor are measured for the circular casing.

• Korean Journal of Materials Research
• /
• v.27 no.10
• /
• pp.513-517
• /
• 2017

An optimum route to fabricate a hybrid-structured W powder composed of nano and micro size powders was investigated. The mixture of nano and micro W powders was prepared by a ball milling and hydrogen reduction process for $WO_3$ and W powders. Microstructural observation for the ball-milled powder mixtures revealed that the nano-sized $WO_3$ particles were homogeneously distributed on the surface of large W powders. The reduction behavior of $WO_3$ powder was analyzed by a temperature programmed reduction method with different heating rates in Ar-10% $H_2$ atmosphere. The activation energies for the reduction of $WO_3$, estimated by the slope of the Kissinger plot from the amount of reaction peak shift with heating rates, were measured as 117.4 kJ/mol and 94.6 kJ/mol depending on reduction steps from $WO_3$ to $WO_2$ and from $WO_2$ to W, respectively. SEM and XRD analysis for the hydrogen-reduced powder mixture showed that the nano-sized W particles were well distributed on the surface of the micro-sized W powders.

• Journal of the Korean Institute of Educational Facilities
• /
• v.22 no.6
• /
• pp.3-11
• /
• 2015

Nowadays, the number of school students in rural area has decreased significantly. For this reason, there are mixed classes among students of different grades in schools in rural area. Moreover, there are several teachers who teach two and more subjects except for the major of teacher so educational environment has been deteriorated. To tackle this problem, the ministry of education has suggested merging small schools in rural area. However, some people believe that merging small schools would make educational environment more worse and would not solve this problem. To solve this problem, this research suggests that the proper solution for educational environment of merging small schools through surveying environment of merging schools.

• Korean Journal of Occupational Health Nursing
• /
• v.26 no.1
• /
• pp.47-54
• /
• 2017

Purpose: The purpose of the study is to examine the impact of job stress on the patient safety nursing activities among nurses. Methods: The subjects of the study are 258 nurses working at 15 small-medium sized hospitals in D city. Data analysis was done using frequency, percentage, average and standard deviation, t-test, one-way ANOVA, $Scheff{\acute{e}}test$, Pearson's correlation coefficient, stepwise multiple regression. Results: The job stress scored average 3.67 and patient safety nursing activity scored average 4.35. Job stress was positively associated with patient safety nursing activity. It explains 9.49% of the variance. Conclusion: Universal and inevitable job stress among nurses should not exceed optimum level to assure patient safety. So, personal and organizational efforts to manage job stress are needed.