• Applied Chemistry for Engineering
• /
• v.16 no.2
• /
• pp.238-242
• /
• 2005

In this work, Polydimethylsiloxane (PDMS) and SU-8 (Microchem, USA) photoresist were used to make the microchannel by soft lithographic method. To investigate the effects of external voltages and widths of the microchannel, we made the microchannel by soft lithographic method. To investigate the effects of external voltages and widths of the microchannel, we made the microchannel with various widths: $100{\mu}m,\;200{\mu}m$ and $300{\mu}m$. And each micorchannel was supplied with external voltage, respectively. As a result, the fluid velocity increased with an increase of the external voltage at the same width. It was speculated that the electrical double layer was condensed and the zeta potential increased with increase of the external voltage. The fluid velocity increased with the microchannel width increase at the same external voltage. It is concluded that the resistance in the microchannel decreased as the microchannel width increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.10a
• /
• pp.267-273
• /
• 2004

This paper targets to define controlling factors of pressure-coupled combustion response and estimate their effects on droplet evaporation process. Dynamic characteristics of hydrocarbon propellant vaporization perturbed by acoustic pressure are numerically simulated and analyzed. 1-D droplet model including phase equilibrium between two phases is applied and acoustic wave is expressed by harmonic function. Effects of various design factors and acoustic pressure on combustion response are investigated with parametric studies. Results show that driving frequency of acoustic perturbation and ambient pressure have important roles in determining magnitude and phase of combustion response. On the other hand, other parameters such as gas temperature, initial droplet size and temperature, and amplitude of acoustic wave cause only minor changes to magnitude of combustion response. Resultant changes in phase of heat of vaporization and thermal wave in droplet highly influence magnitude and phase of combustion response.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.321-331
• /
• 2018

This study examined the life safety factor of residents living in a university village. The results of the study were as follows. First, previous research results and social safety-related research and practical system for a wide range of exterior space, including the driveway of the living space was a relative lack. Based on the survey results, the psychological factors that affect the life safety environment of the living space was found in the exterior space environment. Second, the living safety factors in the exterior space of a one-room residence can be shown by four types, such as occupant monitoring, residential surveillance and area classification, external public space utilization, and pleasant environment maintenance in the architectural planning dimension. Third, the results of research on the exterior space of the university one-room village, and life safety environment of exterior space, such as design of pedestrian street, revealed a very poor resident population and one-room buildings in most areas.

• 한국사회정책
• /
• v.23 no.2
• /
• pp.201-237
• /
• 2016

This paper focuses on Korean and Japanese female workers participating in the outside (secondary) labour market, especially with an attention given to two aspects. First, we explain how females are 'more outsiders' than males in the labour market. Secondly, we investigate M-shape in the female labour market participation by focusing on different proportion of non-standard worker. Then, in order to explain why women keep on being more concentrated in the outer side of the labour market, we examine the development of three policies in Korea and Japan since 1990s. Labour market deregulation policy, female employment policy and lastly, family policy are examined as institutional arrangement. Lastly, we discuss on how institutional combination is associated with females' concentration in the outside labour market in Korean and Japanese dual labour market.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.5
• /
• pp.297-308
• /
• 2022

Most air-breathing aircraft operated in the hypersonic region are equipped with a scramjet engine. In a scramjet engine, a shock wave generated at an inlet acts as a compressor for a general gas turbine engine instead, so total pressure loss caused by the shock wave is considered very important. In this study, to minimize total pressure loss, a method of designing an external compression inlet using isentropic compression surface was proposed, and an external compression inlet with 3-deflection angles and Busemann inlet were designed under the same conditions. After that, through computational analysis, the performance characteristics at off-design conditions were compared. Each inlet shape was truncated according to the length of the 3-ramp external compression inlet, and the boundary layer correction was performed. The isentropic external compression inlet showed superior performance at the design point, but under the off-design conditions, its performance was degraded compared to the 3-ramp external compression inlet.

• The Journal of the Acoustical Society of Korea
• /
• v.29 no.7
• /
• pp.448-457
• /
• 2010

Vibrations and wave propagations in waveguide structures can be analysed efficiently by using waveguide finite element (WFE) method. The WFE method only models the 2-dimensional cross-section of the waveguide with finite elements so that the size of the model and computing time are much less than those of the 3-dimensional FE models. For cylindrical shells or pipes which have simple cross-sections, the external coupling with fluids can be treated theoretically. For waveguides of complex cross-sectional geometries, however, numerical methods are required to deal with external fluids. In this numerical approach, the external fluid is modelled by the boundary elements (BEs) and connected to WFEs. In order to validate this WFE/BE method, a pipe submerged in water is considered in this study. The dispersion diagrams and point mobilities of the pipe simulated are compared to those that theoretically obtained. Also the acoustic powers radiated from the pipe are predicted and compared in both cases of air and water as an external medium.

• Journal of Mushroom
• /
• v.14 no.2
• /
• pp.39-43
• /
• 2016

In this study, we observed differences in the fruit body genesis in with seasonal changes. The mushrooms generated different spines even when under same environmental conditions in equivalent growth chambers during different seasons. The growth chamber conditions were set at $18^{\circ}$, 1000 ppm CO and 95% humidity for uniform primordium formation. Following this, the humidity was reduced to 85% during growth and development. The characteristics of the fruit body were measured: yield (weight), length (size), hardness, and chromaticity. Each measure was relatively compared owing standard data for. We investigated the environmental factors to assess the cause of variation in fruit body. Change in temperature and humidity were especially focused on, apart from climate that can affect mushroom growth. It was observed that temperature and humidity both influence fruit body growth. Not the absolute value of the elevation, there was a change of climate which the temperature is lowered and lowered the humidity can be assumed that the changes in the environmental conditions inside the growth chamber the mushroom growth.

• Journal of Korea Technology Innovation Society
• /
• v.21 no.1
• /
• pp.454-490
• /
• 2018

This paper examined the nonlinear relationships between external knowledge sources and the innovation performance of SMEs (small and medium-sized enterprises). Using 3,218 firm-year panel data in South Korea, this study found that increasing the number of external knowledge channels out of the value chain increases radical innovation. Meanwhile, increasing the number of external knowledge channels within the value chain increases the incremental innovation. Further, the external sources of knowledge both out of and in the value chain had inverted U-shaped relationships on radical and incremental innovation respectively. This finding implies that a mechanism of diminishing returns works in the relationship between the external sources of knowledge and innovation. The study also identified the synergistic effects between the external sources of knowledge out of the value chain and within the value chain, and confirmed that the synergistic effects strengthen the linear mechanism between the external sources of knowledge and innovation. In addition, this study found that the sources of knowledge both out of and within the value chain positively moderate the relationships between R&D investment and radical innovation of SMEs.

• The Journal of the Korea Contents Association
• /
• v.13 no.12
• /
• pp.860-868
• /
• 2013

The purpose of this study is to ensure safety by measuring External radiation dose ratio (ERDR) by traits of patients in many ways after administering radiopharmaceutical($^{18}F$-FDG) for PET Torso scan, and to decrease ERDR of those to RI technologist, caretakers, and those who frequently exposed to radiation by arousing attention to radiation dose. Radiopharmaceutical was administered to 80 patients who conducted PET Torso from January to June, 2013. Radiation dose emitted from the patients was measured according to body shape(BMI), water hydration, height, amount of radiation administration. From the moment immediately after the radiopharmaceutical was administered, ERDR was measured by personal traits of patients. The radiation dose increased in proportion to the administered amount of the radiopharmaceutical, and there was no significant difference depending on the body shape of the patients. When water was supplied and the height was normal, the radiation dose was lower compared with the cases where water was not supplied and height was not normal. There is a need for making efforts to minimize the working time through sufficient education and mock training before those who RI technologist with sources of radiation for complying the radiation safety management rule. And they should minimize the ERDR by wearing a protective gear.

• The Journal of Korean Society for Radiation Therapy
• /
• v.23 no.1
• /
• pp.7-12
• /
• 2011

Purpose: To analyze availability of MR images before and after external beam radiotherapy in brachytherapy, we will acquire MR images before and after external beam radiotherapy and compare the change of direction of uterine cavity and analyze the accuracy of applicator insertion. Materials and Methods: From January 2009 to December 2010, we compared MR images before and after external beam radiotherapy for uterine cervical cancer only with radical purpose treatment. MR images which was acquired after external beam radiotherapy has done with inserted status of CT/MR applicator. Results: As a consequence, the tumor was markedly reduced after external beam radiotherapy. The change of anteflexion of uterus turned into retroflexion of the uterine cavity was 17.1%. The case of wrong insertion of tandem include direction or length was 14.3%. Conclusion: According to MR images taken after external beam radiotherapy, we recognized not only reduced the tumor volume but the marked change of exact direction or length of the uterine cavity. So the confirmation of accurate insertion based on MR images before brachytherapy could be very helpful for optimal brachytherapy treatment planning with reduced applicator insertion errors.