• Journal of the Korea Safety Management & Science
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• v.17 no.1
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• pp.75-84
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• 2015

Successful development of weapon systems requires a stringent verification and validation (V&V) process due to the nature of the weapons in which continual increase of operational capability makes the system requirements more complicated to meet. Thus, test and evaluation (T&E) of weapon systems is becoming more difficult. In such a situation, live fire tests appear to be effective and useful methods in not only carrying out V&V of the weapon systems under development, but also increasing the maturity of the end users operability of the system. However, during the process for live fire tests, a variety of accidents or mishaps can happen due to explosion, pyro, separation, and so on. As such, appropriate means to mitigate mishap possibilities should be provided and applied during the live fire tests. To study a way of how to accomplish it is the objective of this paper. To do so, top-level sources of hazard are first identified. A framework for T&E is also described. Then, to enhance the test range safety, it is discussed how test scenarios can be generated. The proposed method is based on the use of the anticipatory failure determination (AFD) and multiple event tree analysis (ETA) in analyzing range safety. It is intended to identify unexpected hazard components even in the environment with constraints. It is therefore expected to reduce accident possibilities as an alternative to the traditional root-cause analysis.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.8-14
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• 2011

The effect of flooding and soil salinity on the growth of yam (Dioscorea batatas) were studied on the experimantal site temporally established in the south-eastern part of Saemangeum Reclaimed Tidal Land (near Gwanghwal myun, Gimjae-gun, Jellabukdo, Korea). Yam seedlings planted by using aerial bulblet as alternative of sliced tubers, were grown for 20-days and transplanted in black-vinyl mulched ridges (about 20 cm in height) at 70cm interval by $20{\times}60cm$ spacing in the $4^{th}$ of May, 2010. Soil salinity was maintained at lower than 1.2 ds $m^{-1}$ during the growing period and did not result to salt injury in all plants. However, flooding injury very seriously led to plant death and plant mortality rates at $67{\pm}21$ and $82{\pm}9%$ of yam plants in the compost and no compost treatment, respectively, died by heavy flooding during the rainy summer season. The main reasons of the flooding injury included the decreased rainfall acceptable capacity (RAC) after the rising of water table and a slowdown of water infiltration rate after the formation of an impermeable soil crust in the furrow bottom with continuous and heavy downpour during the rainy summer season. The effect of compost treatment was not statistically observed because of the severe spatial difference caused by wet injury, although yam tuber yield was higher at 30 kg $10^{-1}$ in the compost treatment than in the no-compost treatment at 20 kg $10^{-1}$. However, the size of tuber ranged at 1.23 to 1.60 cm in diameter and 3.7 to 5.0 cm in length in all both treatment, which means they are still reproducible for the next cropping season. Conclusively, proper counter-flooding measure and soil salinity control critically important for successful yam production in Saemangeum Reclaimed Tidal Land.

• Journal of Technology Innovation
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• v.13 no.2
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• pp.97-131
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• 2005

This paper has discussed several issues regarding the barriers and opportunities for technological catch-up by the late-comer countries and firms. As one of the barriers to technological catch-up, the paper emphasizes the uncertainty involved with the third stage of learning how to design. The barriers arise because as the forerunner firms refuse to sell or give license to successful catching-up firms who thus have to design the product by themselves. The paper discusses how to overcome this barrier. It also notes that if the crisis of design technology is a push factor for leapfrogging, arrival of new techno-economic paradigm can serve as a pull factor for leapfrogging, serving as a winder of opportunity. The, it emphasized the two risks with leapfrogging, namely the risk of choosing right technology or standards and the risk of creating initial markets, and how to overcome these risks. It discusses how to overcome these risks in leapfrogging, and differentiates diverse forms of knowledge accesses. Then, the paper takes up the issue of whether there can be a single common or several models for catch-up. A common element of catching-up is to enter new markets segments quickly, to manufacture with high levels of engineering excellence, and to be first-to-market by means of the best integrative designs. This observation is supported by the fact that Korea and Taiwan has achieved higher levels of technological capabilities in such sectors as featured by short cycle time of technology. The possibility of two alternative models for catch-up is also discussed in terms of the key difference between Korean and Taiwan, especially in the position toward the source of foreign knowledge and the paths taken toward the final goal of OBM. Taiwan followed the sequential steps of OEM, ODM and OBN, in collaboration or integration with the MNCs. Korean chaebols jumped from OEM directly to OBM even without consolidating design technology.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.419-427
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• 2017

In mountainous rivers, the drag force acting on cobbles abundant in the riverbed surface is important in predicting behavior and response of the river. However there is little research for the drag coefficients of cobbles. This paper is to carry out the experiments for drag force of cobble and analyze the relation between the cobble shape and the drag coefficient. The effects of the shape factor on the drag coefficients $C_D$ when the long axis or the short axis of the cobbles are parallel to the direction of flow velocity were analyzed. The coefficient of drag force increased with the nominal diameter Reynolds number $R_{ep}$. The drag coefficients are greater in short axis than long axis. The coefficient of determination of the relation between $C_D$ and $R_{ep}$ is greater in long axis than short axis. This means that the drag forces acting on the irregularly-shaped cobbles depend on the axis. A change of the drag force distribution has brought about the alternative swing of cobbles. For $R_{ep}$ > 12,000, the amplitude of the swing has been increased sharply and especially was greater in short axis than long axis.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.3
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• pp.270-278
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• 2000

This study was conducted to compare the vein graft with the nerve graft, and evaluated the availability of the vein graft on the reconstruction of the inferior alveolar nerve defect. The experimental animals were 12 rabbits weighing $1.5{\sim}2.0kg$, divided into 3 groups : sham operation group, vein conduit group and nerve graft group. All nerves were excised and histomorphometric analysis was performed at 2, 4, 6, 12, 16 weeks after operation. The obtained results were as follows. 1. Histologic examination revealed the regenerated nerve fibers within the lumen of the vein graft and nerve graft at 6 weeks after repair. 2. Axon diameter was significantly larger in nerve graft group(p<0.05) than in vein graft group at 6weeks, and larger in nerve graft group than in vein graft group at 16weeks. 3. Axon density was higher in the vein graft group at 16 weeks. 4. The myelin of the regenerated nerve fibers in distal segment of the vein graft group was thick, approaching the proximal segment at 16weeks. This means remyelination in distal segment in the vein graft group. These results suggested that autogenous vein graft may be used as an alternative to autogenous nerve graft.

• The Journal of Society for e-Business Studies
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• v.20 no.2
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• pp.125-140
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• 2015

It is general that the impact of supply chain risk spread out to the whole network along the connected structure. Due to the risk propagation the probability to exposure a certain risk is affected by not only the characteristics of each risk factor but also network structure. It means that the structural connectivity among vertices should be considered while designing supply chain network in order to minimize disruption cost. In this research, the betweenness centrality has been utilized to quantitatively assess the structural vulnerability. The betweenness centrality is interpreted as the index which can express both the probability of risk occurrence and propagation of risk impact. With the structural vulnerability index, it is possible to compare the stability of each alternative supply chain structure and choose the better one.

• Journal of Forest and Environmental Science
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• v.33 no.3
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• pp.187-196
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• 2017

The use of unmanned aerial vehicles (UAV) for the estimation of tree height is gaining recognition. This study aims to assess the effectiveness of tree height estimation of Pinus densiflora Sieb. et Zucc. and Pinus koraiensis Sieb. et Zucc. using digital surface model (DSM) generated from UAV-acquired imageries. Images were taken with the $Trimble^{(R)}$ UX5 equipped with Sony ${\alpha}5100$. The generated DSM, together with the digital elevation model (DEM) generated from a digital map of the study areas, were used in the estimation of tree height. Field measurements were conducted in order to generate a regression model and carry out accuracy assessment. The obtained coefficients of determination (R2) and root mean square error (RMSE) for P. densiflora (R2=0.71; RMSE=1.00 m) and P. koraiensis (R2=0.64; RMSE=0.85 m) are comparable to the results of similar studies. The results of the paired two-tailed t-test show that the two tree height estimation methods are not significantly different (p-value=0.04 and 0.10, alpha level=0.01), which means that tree height estimation using UAV imagery could be used as an alternative to field measurement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.2
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• pp.1-8
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• 2011

Traffic congestion is a source of significant economic and social costs in urban areas. Intelligent Transportation Systems (ITS) are a promising means to help alleviate congestion by utilizing advanced sensing, computing, and communication technologies. This paper proposes and investigates a basic and advanced ITS framework Advanced Traveler Information System (ATIS) using wireless Vehicle to Roadside (Centralized ATIS model: CA model) and Vehicle to Vehicle (DeCentralized ATIS model: DCA model) communication and assuming an ideal communication environment in the typical $6{\times}6$ urban grid traffic network. Results of this study indicate that an ATIS using wireless communication can save travel time given varying combinations of system characteristics: traffic flow, communication radio range, and penetration ratio. Also, all tested metrics of the CA and DCA models indicate that the system performance of both models is almost identical regardless of varying traffic demand and penetration ratios. Therefore, DCA model can be a reasonable alternative to the fixed infrastructure based ATIS model (CA model).

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.700-708
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• 2007

A midline deviation is divided into three types, such as a skeletal midline deviation, a dental midline deviation, and a combination. Among them, the midline deviation which appear in the early mixed dentition without any skeletal problem can be managed differently by the stage of dental development. The location of the permanent incisors can be improved without using artificial force in consideration of the condition of the space, the eruption timing or the eruption path of the adjacent permanent teeth in early mixed dentition, especially when the permanent incisors are erupting. Therefore, the space supervision technique, which can have the teeth align themselves utilizing physiologic events such as sequence or timing of the eruption of permanent teeth, can be an alternative to orthodontic movement. This case report describes midline deviation improvement by space supervision.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.3
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• pp.79-88
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• 2011

In the context of sustainability which is understood as equilibrium among three elements; human, space and time, the imbalance within the Seoul metropolitan area hinders its own area or the nation from development. Claims for the balanced development in the area are set up on the premise that there is a locational order of priority among the zones named 'overpopulation suppression', 'growth management' and 'conservation'. Based on the systematic consideration of competitiveness this study adopts the premise as a research hypothesis. Factor scales derived from the factor analysis, a kind of multivariate dependence analysis play an important role in this research process since they are measured by interval-ratio level and can be used for dependent variables in the statistical analysis. The hypothesis test carried out by means of the analysis of variance(ANOVA) concludes that the hypothesis assuming no difference in the competitiveness is rejected but the alternative hypothesis of the locational order mentioned above should be adjusted. Eigenvalues derived from the factor analysis could be used as weights for aggregate factor scales and the scales show that the priority is in the order of growth management - overpopulation suppression - conservation zones. This finding has also a significant implication that the countermeasures to cope with the lowering of the competitiveness resulted from the continuous and absolute restraints should be provided. And strategic approaches which are composed of key factors for each zone are deducted from in-depth review. (1) overpopulation suppression zone; health-welfare, educational base, public service factors, focusing on health-welfare one, (2) growth management zone; public service factor and (3) conservation zone; health-welfare, educational base factors, also focusing on health-welfare one.