• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.11
• /
• pp.112-119
• /
• 1996

Impact ionization model in GaAs has been presented by modified keldysh formula with two sets of power exponent of 7.8 and 5.6 in study. Impact ionization rate is derived from fermil's golden rule and ful lenergy band stucture based on empirical pseudopotential method. Impact ionization rates show anisotropic property in low energy region (<3eV), but isotropic in high energy region (3>eV). Full band monte calo simulator is coded for investigating the validity of the GaAs impact ionization model, and validity is checked by comparing impact ionization coefficients with experimental values and ones in anisotropic model. Valley transitions to energy alteration are explained by investigating electron motion in brillouin zone for full band model to electric field variation.

• Journal of Environmental Impact Assessment
• /
• v.23 no.1
• /
• pp.51-65
• /
• 2014

ODA projects such as multi-purpose dam, industrial complex, road construction etc. have resulted in environmental damage and resident relocation including destruction of site of living. Even the grandiose developments as ODA projects have made clear the value clashes between development and environmental conservation, and have brought about conflicts between public interests and public environmental right, and the discordance between public interests and private property rights in the recipient country. This study summarizes and analyses the Korea's ODA projects and will suggest the public participation and governance system based on Saemaul Movement, Strategic Environmental Assessment and Environmental Impact Assessment based on the guideline of OECD DAC, and emphasize Strategic Environmental Assessment and Social Impact Assessment in the procedure of ODA projects. In the future the ODA project should be implemented for the overcome of poverty and response to climate change based on the experience and trial and errors of Korea's compact growth and past ODA projects.

• Journal of the Korean Society of Safety
• /
• v.23 no.6
• /
• pp.34-37
• /
• 2008

The composite materials are widely used in the many applications of industry as well as aerospace field because of their high specific stiffness and strength which benefits the material and provides potential energy savings. However, composite materials also have a low property about external applied impact. In this paper, impact tests were conducted on different sample types(glass, carbon and kevlar composite) to obtain information such as absorbed energy and composite deformation using an instrumented impact test machine (DYNATUP 8250). 3 type samples were compared to experimental results. The data from impact test provided valuable information between the different type samples by wet lay up. This paper shows results of that kevlar composite has larger absorption energy and deformation than others.

• Journal of Mechanical Science and Technology
• /
• v.19 no.7
• /
• pp.1424-1431
• /
• 2005

In this study, head injury by impact force was evaluated by numerical analysis with 3-dimensional finite element (FE) model. Brain deformation by frontal head impact was analyzed to evaluate traumatic brain injury (TBI). The variations of head acceleration and intra-cranial pressure (ICP) during the impact were analyzed. Relative displacement between the skull and the brain due to head impact was investigated from this simulation. In addition, pathological severity was evaluated according to head injury criterion (HIC) from simulation with FE model. The analytic result of brain damage was accorded with that of the cadaver test performed by Nahum et al.(1977) and many medical reports. The main emphasis of this study is that our FE model was valid to simulate the traumatic brain injury by head impact and the variation of the HIC value was evaluated according to various impact conditions using the FE model.

• Korean Journal of Applied Biomechanics
• /
• v.22 no.2
• /
• pp.237-242
• /
• 2012

The purpose of this study was (a) to develop carbon nanotube-based shock absorbers for reducing potentially harmful impact forces and excessive foot pronation, and (b) to briefly determine how the effects of carbon nanotube-based shock absorbers on biomechanical variance during drop landing. A university student(age: 24.0 yrs, height: 176.2 cm, weight: 679.5 N) who has no musculoskeletal disorder was recruited as the subject. Hardness, specific gravity, tensile strength, elongation, 100% modulus, tear strength, split tear strength, compression set, resilience, vertical GRF, and loading rate were determined for each material. For each dependent variable, a descriptive statistics was used for different conditions. The property test results showed that tensile strength, tear strength, split tear strength, compression set, and resilience in carbon nanotube-based shock absorbers were greater than general Ethylene Vinyl Acetate(EVA). These indicated that resistance against variable strength in developed carbon nanotube-based shock absorbers were greater than general EVA. In vertical GRF of CNTC was less than those of EVA during drop landing and loading rate of CNTC was greater than EVA. It seems that the use of CNT can be a effective way of reducing and controlling shock from impact.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.173-178
• /
• 2005

The tile construction methods for existing have been used materials within limit which adhesion by wet method in masonry wall and concrete structure. These existing adhesive tech can caused many problems in construction of large and reform tile, after that it can be happened loose scale, peel off, falling off tile by heat and vibration or impact. In according to, this study is to test tile for bond stability, adhesive property by impact, vibration. low property by heat and then, we have the results as below; (1) The tile adhesive stability can be effected as adhesive area between bond agent and tile, adhesive area can more wide and press enough to ensure property. (2) Existing adhesive strength and standard relative tile construction is limited to adjust performance tile on the concrete and masonry wall. In summary, It is necessary to establish standard of performance and test method to ensure tile adhesive salability in dry wall.

• Journal of Environmental Science International
• /
• v.20 no.10
• /
• pp.1309-1317
• /
• 2011

This study selected 6 river reach, which have various curved-channel, included in an object of study as making the Nakdong River, which is a real nature river, as a point of an object of study by using SMS RMA-2 model, a 2D numerical analysis model, and applied project flood and analyzed and examined characteristic of hydrological property and super-elevation, which includes characteristic of the velocity of a moving fluid. As a result, in a river reach, whose width is wide, angle of curved-channel has impact on the velocity of a moving fluid of inside of curved-channel and in a river reach, whose width is narrow, the radius of curvature and width of the river have impact on the velocity of a moving fluid of inside of curved-channel. Also it found out that the ratio of reduction in water-level of inside of curved-channel is more bigger than ratio of increasing in water-level of outside of curved-channel when project flood is increasing and angle of curve is increasing. Based on this, this study would be used as a expectation of danger and preliminary data in planning real river or a business, that creates an environment.

• Journal of the Korean Society of Costume
• /
• v.58 no.9
• /
• pp.151-165
• /
• 2008

The purpose of this study is to establish theoretical basis for relationship marketing exercised in the esthetic industry and to empirically analyze causal relationship among factors of esthetic relationship marketing, together with quality and the performance of the relationship. With empirical research, this study finds out that such relationship marketing factor as customer orientation, employee' expertise, physical property have an impact on the relationship quality between customers and esthetic salons' service providers. Customer satisfaction and trust increase the relationship between service providers and customers, and this also increases repurchase intention of the customer towards the service providers. These are significant findings in that they illustrate the importance of employee' expertise and customer orientation, and physical property in determining satisfaction and trust. The result of this study shows that service providers can enhance customer satisfaction and trust by utilizing relationship marketing more effectively, and can preserve the current customer basis.

• Journal of Internet of Things and Convergence
• /
• v.9 no.6
• /
• pp.83-92
• /
• 2023

The purpose of this study is to provide a rational management strategy to improve the management performance of companies through intellectual property activities. Through this study, we aim to explore countermeasures to strengthen competitiveness in a changing global environment. A survey of 200 companies was conducted from September 1 to October 30, 2023. Statistical analysis was conducted using frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, multiple regression analysis, and difference analysis. The conclusions are as follows. First, the impact of intellectual property activities on management performance was found to be creation and utilization. Second, the impact of management strategies on management performance was found to be differentiation strategy, cost advantage strategy, and concentration strategy. Third, cost advantage strategy has a partial mediation effect on the relationship between creation activities and managerial performance of intellectual property activities. Fourth, the differentiation strategy has a partial mediating effect on the relationship between the creation of intellectual property activities and managerial performance. In addition, differentiation strategy has a full mediating effect on the relationship between the utilization of intellectual property activities and performance. Fifth, concentration strategy has a partial mediating effect on the relationship between intellectual property activity utilization and management performance. Sixth, there is a difference between creation activities, protection activities, utilization activities, cost advantage strategy, differentiation strategy, financial performance, and non-financial performance based on venture certification status. As the importance of intellectual property is increasing in the era of technological hegemony, IoT companies will need to improve their management performance through venture certification and strategies utilizing intellectual property in order to secure future competitiveness. Based on this study, we hope that IoT companies will maximize their performance by implementing efficient strategies that consider IP activities.

• Journal of Welding and Joining
• /
• v.5 no.2
• /
• pp.27-34
• /
• 1987

The characteristics of arc sprayed layer were studied with hardness test and microstructural observation. The erosion resistance of arc sprayed layer was also evaluated using a method of steel ball blasting test which was proposed in this study as a test method for measuring the erosion properties in the impact wear condition. By an impact of the molten droplets on the redeposited substrate, lamella structure was formed which contains laminated oxide layers, fissures, and porosities. As a result of mechanical tests, it was shown that the sprayed specimen showed higher hardness than the substrate, but it resulted in higher erosion rate than the substrate. The poor erosion property obtained with a sprayed coating was considered to be attributable to easy flaking off the the layers laminated with brittle oxide layers.