• Korean small business review
• /
• v.43 no.3
• /
• pp.91-117
• /
• 2021

The purpose of this study is to study the effect of internatioanl entrepreneurial orientation of small and medium-sized Chinese manufacturing companies on export performance. A total of 183 corporate data were used for empirical analysis for Chinese manufacturing export companies. In summary, first, international entrepreneurial orientation was shown to have a significant positive effect on export performance, second, international etrprenurial orientation was shown to have a significant positive effect on absorption capacity, and third, the stronger environmental dynamics and network capacity, the stronger international business orientation and export ability. The implications of this study are summarized as follows. It suggests that the more innovative, enterprising and risk-taking Chinese SMEs are, the better their export performance and the better their ability to absorb foreign knowledge. It also suggests that small business managers must continue to strengthen their network capabilities to improve export performance through international entrepreneurial orientation, and this relationship is further strengthened in a dynamic environment. It also suggests that the impact of firm's absorption capacity on export performance will weaken over time.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.12
• /
• pp.13-22
• /
• 2008

Fourteen calibration ehamber tests were performed using one cylindrical and two tapered piles with different taper angles to investigate the changes of the bearing capacity of tapered piles with soil state and taper angle of piles. The results of calibration chamber tests show that the ultimate base resistance of tapered piles increases with increasing mean stress and relative density of soil. It also increases with increasing taper angle for medium sand, but with decreasing taper angle for dense sand. The ultimate shaft resistance of tapered piles increases as vertical and horizontal stresses, relative density and taper angle increase. Based on the results of model pile load tests, a new design method with shape factors for estimation of the bearing capacity of tapered piles is proposed considering the effect of soil state and taper angle on bearing capacity of tapered piles. In order to check the accuracy of predictions calculated using the new method, middle-scale field pile load tests were also conducted on cylindrical and tapered drilled shafts in clayey sand. Comparison of calculated values with measured ones shows that the new design method produces satisfactory predictions tor tapered piles.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 1998.10a
• /
• pp.2-4
• /
• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• Journal of the Korean Society of Radiology
• /
• v.13 no.6
• /
• pp.879-887
• /
• 2019

The purpose of this study is to establish a physiological injection protocol according to body weight, in order to minimize amount of contrast medium and optimize contrast enhancement in pediatric patients performing thoracic CT examinations. The 80 pediatric patients under the age of 10 were studied. Intravenous contrast material containing 300 mgI/ml was used. The group A injected with a capacity of 1.5 times its weight, and groups B, C and D added 5 to 15 ml of normal saline with a 10% decrease in each. The physiologic model which can be calculated by weight about amount of injection of contrast medium and normal saline, flow rate and delay time were applied. To assess image quality, measured average HU value and SNR of superior vena cava, pulmonary artery, ascending and descending aorta, right and left atrium, right and left ventricle. CT numbers of subclavian vein and superior vena cava were compared to identify the effects of reducing artifacts due to normal saline. Comparing SNR according to the contrast medium injection protocol, significant differences were found in superior vena cava and pulmonary artery, descending aorta, right and left ventricle, and CT numbers showed significant differences in all organs. In particular, B group with a 10% decrease in contrast medium and an additional injection of saline showed a low degree of contrast enhancement in groups with a decrease of more than 20%. In addition, the group injected with normal saline greatly reduced contrast enhancement of subclavian vein and superior vena cava, and the beam hardening artifact by contrast medium was significantly attenuated. In conclusion, the application of physiological protocol for injection of contrast medium in pediatric thoracic CT examinations was able to reduce artifacts by contrast medium, prevent unnecessary use of contrast medium and improve the effect of contrast enhancement.

• 한국기계연구소 소보
• /
• s.14
• /
• pp.157-168
• /
• 1985

In cargo vessels, hatch covers are used to prevent sea water from penetrating into the cargo hold and to keep the vessels buoyant. And also they can be used as cargo loading devices as in container ships. In this paper, hatch covers are classified according to their operation method and their characteristics are briefly demonstrated. Systematic description on the scantling of the hatch cover panel and how to determine the capacity of the hydraulic power system fir folding hatch cover panels are also presented. The hydraulic power system is selected from the result of dynamic analysis of the movements of the hatch cover panels when stored on the upper deck. The hatch coaming height is determined as shortly as the hydraulic cylinders can be installed. This study deals with the hatch cover system of the medium sized multi-purpose cargo vessel, but the results of this study can be applied to large-sized cargo vessels with a slight change of the input data in the calculations. Further research on the high pressure pump, hydraulic cleating system and hydraulic piping will realize domestic production of the whole hatch cover system which have been supplied from foreign makers until now

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1658-1660
• /
• 2004

Use of higher voltage and higher capacity of power systems and their equipment is leading to an increase in the size of the entire system. In order to reduce the cost of constructing a substation, it is necessary to reduce the size of equipment. So, this paper described optical sensor, which exploited the electric and magnetic potentiometer to sense the measured voltage and current of medium voltage GIS. It can be used both in measurement and in protection relays as its well linearity, rapid response, broad dynamic range, wide frequency band, no magnetic saturation, small in volume, light weight, and saft in insulation.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1894-1904
• /
• 2011

The Light Rail Transit (LRT) System which has medium transport capacity between subway and bus(5,000-25,000 persons per hour) is the most advanced transportation system. It has many benefits, cheap construction, operational costs through driverless and flexible route planning. Also, the rubber tired AGT (K-AGT) of various LRT has a rubber wheels and side guide. The side guide type has an many advantages. but occur a vibration and friction noise through contact between guide rail and wheel. Most of point that decreased comport is vibration thorough the guide contact. In this paper, It is purpose to improve the maximum running speed of rubber tired AGT localization bogie which is currently developed from 70km/h to 80km/h. To satisfy comport index of railway vehicle that is required in performance test. we examined coefficient of bogie suspension which is designed.

• Proceedings of the Safety Management and Science Conference
• /
• 2010.11a
• /
• pp.81-91
• /
• 2010

Daily workers in construction sites rarely receive the benefit of systematic safety and health training as they are required to move from one construction site to another in response to the start, completion, and repetition of construction works. Also, small- to medium-sized construction sites often lack the capacity to train their workers. Therefore, as in the advanced countries, basic safety training system for construction workers should be conducted in the industrial-level, rather than in individual workplace-level, to make the training more effective. By doing so, only workers with the basic safety training will be able to engage in construction works. Consequently, accidents in the construction industry will decrease, as workers themselves who are at the forefront of the construction worksites are empowered to play the central role in accident prevention activities.

• Journal of IKEEE
• /
• v.13 no.2
• /
• pp.108-117
• /
• 2009

In recent years, one of alternatives for constructing RFID networks that provide mobile services is using wireless sensor networks (WSN) to enhance network capacity, utility and scalability. Due to absence of compatible reader anti-collision control and channel capture phenomenon, the medium access control protocols as used in the RFID networks lead to reader collision and starvation problem. In this paper, we develop a MAC protocol which is called Enhanced Collision Avoidance MAC (ECO) to avoid reader to reader collisions in an integrated RFID network. ECO is a CSMA-based MAC protocol, and operates on integrated nodes which consist of a RFID reader and a mote. Performance evaluation shows superior results to pure-CSMA protocols under dense deployment environments, both in number of failures and in throughput.

• Steel and Composite Structures
• /
• v.24 no.2
• /
• pp.265-276
• /
• 2017

Structures are designed in such a way that they behave in a nonlinear manner when subject to strong ground motions. Energy concepts have been widely used to evaluate the structural performance for the last few decades. Energy based design can be expressed as the balance of energy input and the energy dissipation capacity of the structure. New research is needed for multi degree of freedom systems (MDOFs)-real structures- within the framework of the energy based design methodology. In this paper, energy parameters are evaluated for low-, medium- and high-rise steel special concentrically braced frames (SCBFs) in terms of total energy input and hysteretic energy. Nonlinear dynamic time history analyses are carried out to assess the variation of energy terms along the height of the frames. A seismic energy demand spectrum is developed and hysteretic energy distributions within the frames are presented.