• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.7
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• pp.569-574
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• 2007

In this paper, the reliability (NBTI degradation: ${\Delta}V_{th}$) and device characteristic of nano-scale PMOSFET with plasma nitrided oxide (PNO) is characterized in depth by comparing those with thermally nitrided oxide (TNO). PNO case shows the reduction of gate leakage current and interface state density compared to TNO with no change of the $I_{D.sat}\;vs.\;I_{OFF}$ characteristics. Gate oxide capacitance (Cox) of PNO is larger than TNO and it increases as the N concentration increases in PNO. PNO also shows the improvement of NBTI characteristics because the nitrogen peak layer is located near the $Poly/SiO_2$ interface. However, if the nitrogen concentration in PNO oxide increases, threshold voltage degradation $({\Delta}V_{th})$ becomes more degraded by NBT stress due to the enhanced generation of the fixed oxide charges.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.473-481
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• 2016

Thick plate is currently widely used in shipbuilding due to the increasing of size of ships. However, its use has increased welding groove angles and volume. The welder's technique must be good enough to improve productivity while preventing defects. Generally, the groove angle can be reduced to less than a flux-cored arc welding (FCAW) machine setting of $35{\pm}5^{\circ}$, requiring fewer welding passes while maintaining high productivity and reduced heat input. Therefore, welding technique can be prevented by improved mechanical properties and welding deformation. Welding defects such as lack of fusion (LF), lack of penetration (LP) and hot cracking should be considered when reducing the groove angle for related applications. In this study, a welding groove angle of $25{\pm}5^{\circ}$ is verified as suitable for FCAW design and fabrication. The experimental results confirm the effects on the strength characteristics of FCAW weldment when reducing groove angle to improve the productivity of shipbuilding industries.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.65-70
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• 2019

Simple fabrication of a powdered Ge-reduced graphene oxide (Ge-rGO) composite via spray pyrolysis and reduction is introduced herein. Successful incorporation of the rGO nanosheets with Ge hindered the aggregation of Ge and conferred enhanced structural stability to the composite by alleviating the mechanical stress associated with drastic volume changes during repeated cycling. The Li-ion storage performance of Ge-rGO was compared with that of powdered Ge metal. The reversible discharge capacity of Ge-rGO at the $200^{th}$ cycle was $748mA\;h\;g^{-1}$ at a current density of $1.0A\;g^{-1}$ and Ge-rGO showed a capacity of $375mA\;h\;g^{-1}$ even at a high current density of $5.0A\;g^{-1}$. The excellent performance of Ge-rGO is attributed to the structural robustness, enhanced electrical conductivity, and formation of open channels between the rGO nanosheets, which facilitated electrolyte penetration for improved Li-ion diffusion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.21-29
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• 2017

Cold joint caused by construction delay is vulnerable to shear stress and it allows more rapid chloride penetration and diffusion. In the paper, investigation of chloride diffusion coefficient is performed for 1-year cured concrete considering compressive and tensile loading level and cold joint. The results are compared with the previous results in 91-day cured concrete. In the 1-year cured concrete without loading, 10.7% and 10.5% of diffusion reduction are evaluated for those in 91-day cured concrete, respectively. The reduction ratios are almost similar however the result in cold joint concrete shows much higher values. The results in 1-year cured concrete under 30% and 60% of compressive loading show reduction of chloride diffusion by 10.9% and 5.8% compared with 91-day cured results, which is caused by steady hydration of cement particles, so called, time effect. In the case of tensile loading, the differences in results are not significant regardless of time effect and cold joint since micro cracks which is weak point of concrete is much dominant despite of long term curing.

• Journal of the Korean Institute of Navigation
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• v.21 no.3
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• pp.1-18
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• 1997

From the beginning of 1990s , also in the shipping industry, especially liner shipping industry competition has been more intensive and difference of the service quality among shipping companies has been learned . On the other hand, a shipping company has some limitations to do its international mission for itself just by broadening service area. For this reason, the necessity for the global strategi alliance among the shipping companies, which is orginally aimed at sharing of facilities and organixation, has been developed. Through strategic alliance, liner shipping companies do not need to input the additional capitals to increase the material assets such as vessel capacity and spread the risk by the enlargement of the market. Also, they can secure the competitive edge through efficient utilizaton of assets. The purpose of strategic alliance of Hanjin Shipping Ltd., can be summarized as follows ; broadening of service area, cost reduction through vessel sharing, realization of rationalized shipping service by terminal and equipment or facilities sharing. Liner strategic alliances are agreement among liner companies to pol their equipment , andterminals for joint operations and services in which each alliance partner continues to serve its market using jointly operated or used inland feeders,inland terminals, port terminals, and mainline fleets of ship as well as joint pools of containers and equipment. Strategic alliances are generally more formal agreements than consortia and impose longer term and far reaching obligation on their members. It also acts as one in developing and advancing the strategic aims of the alliance members. The most important objective for liner strategic alliances is cost reduction and improvement in capital asset utilization. Main aims of strategic alliance drawn in this paper, can be enumerated follows : 1. improvements in service frequency and quality : 2. improvements in vessel and equipment utilization and thereby reductions in fixed and variable cost ; 3. improvements in market shares and high value cargo booking ; 4. reductions in intermodal storage and port terminal throughput costs ; 5. improvements in negotiating powers with ports and feeder transport providers ; 6. reduction in financial and other fixed costs such as insurance; 7. coordination and integration of MIS and EDI systems and service for greater efficiency and market penetration ; and, 8. improvements in logistic chain management and economic of scale by equipment depot, terminal, and vessel sharing.

• Clinics in Shoulder and Elbow
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• v.2 no.2
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• pp.187-198
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• 1999

Purpose: The authors compared the results of Ender nailing for the proximal humerus fractures with those of the conservative methods radiographically. Materials and Method: Nine patients(mean age: 69 years.) received Ender nailing, and the other nine patients, conservative treatments(mean age: 73 years). All fractures were 2 part fractures. The Ender nails were inserted either through posterior elbow approach or transepicondylar approach. A simple Velpeau bandage was applied to the conservative treatment group. The average follow-up was 15 months. Results: The initial status of the anatomical reduction, i.e., the values of the medial shift, overlapping and the varus agulation, were little changed at follow-up radiographs in both the Ender nailing group and the conservative treatment group. There was no significant difference for the status of anatomical reduction between the Ender nailing group and the conservative treatment group. The stability of fixation by Ender nails, i.e., the degree of fanning out of the nails was poor in most cases. Not a few problems/complications happened in cases of Ender nailing group; back­ing out of the nail in three cases, penetration of the nails into the humeral heads in 3, fractures or cracking of the humerus around the nail insertion area in 4 and reduction loss in one. Conclusion: We could not get better results with the use of Ender nail. We use no longer Ender nails for the proximal humerus fractures. Further studies are needed for the better option for the proximal humerus fractures.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.289-300
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• 2013

In this study, two types of wetland plants, Eichhornia crassipes (a floating plant) and Ceratophyllum demersum (a submerged plant) were introduced to wetland mesocosms to understand how the water properties of wetlands such as pH, dissolved oxygen content, water temperature, oxidation reduction potential, and nutrient concentrations are affected by different types of wetland plant. The floating plant lives on the water surface and can block light penetration; it exhibited the lowest water temperature and temperature difference between lower and upper layers. After the addition of contaminants, the dissolved oxygen (DO) concentration decreased abruptly but recovered continuously in all mesocosms; especially the submerged plants, which photosynthesize in water, showed the largest increases in DO and diel periodicity DO, as well as in pH value. The oxidation-reduction potential in both water and sediment were affected by the presence of wetland plants and plant type and the results suggest that various aspects of wetland biogeochemistry are affected by the presence and type of wetland plants. The total nitrogen and phosphorous concentrations in water decreased in the following order: Water only < Water + Soil < Floating Plants < Submerged Plants. Although both floating and submerged plants can control algal concentrations, the effect was more prominent for floating plants.

• Clean Technology
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• v.25 no.3
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• pp.263-272
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• 2019

Air pollutants have a high impact on everyday life as well as on human health; therefore, new technologies such as low-emission vehicles and add-on systems for air pollutant reduction are needed for our society. However, the environmental benefits and costs of those technologies are not taken into account in existing economic feasibility assessments, which is a barrier that needs to be overcome for green technology to achieve wide dissemination and fast penetration in the market. Thus, this study develops a methodology to assess the economic feasibility of an air pollutant reduction technology by taking into account the social costs from air pollutants and carries out a case study to validate the methodology. Because the social unit costs for air pollutants have not been evaluated yet in South Korea, the methodology uses the social unit costs evaluated for the European Union that are then converted to those for South Korea based on the measuring criteria for vehicle emission gases, parity purchasing price, foreign currency exchange rate, and customer price index. The social unit costs for South Korea are used to assess economic feasibility. A case study was performed to assess the economic feasibility of a dual fuel system using diesel and compressed natural gas by taking into account social costs from air pollutants as well as economic costs. This study could contribute to assessing the true economic feasibility of green technology, projects, and policy related with air pollutant reduction.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.826-832
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• 2016

Reduced greenhouse gas effect induced by LID (Low Impact Development) technique application in tramway construction was quantified to increase environmental benefit as part of an overall economic assessment. In addition, by application of penetration type permeable blocks, the effect of the urban water cycle was examined as a special assessment item in the policy analysis. The carbon emission ratios of the permeable turf block, according to the turf coverage rate (100%, 50% granite, and 50% HDPE), against the concrete track construction were -184.7%, -127.3%, and -116.3%, respectively. The carbon emission ratios of permeable blocks with granite and HDPE were 30.1% and 52.5%. In the case of the penetration type permeable block, it was possible to store rainfall in the block until 90mm/hr of rainfall intensity (94.3% of water reserve rate); therefore, this method was effective as part of the urban water cycle system. As a result, an increased environmental benefit from LID technique application is expected in tramway construction; this needs to be considered as a policy factor in AHP analysis.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.459-468
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• 2001

The Average Coordinate Referenee System (ACRS) method is developed to reduce experimental errors in human locomotion analysis. Experimentally measured kinematic data is used to conduct analysis in human modeling, and the model accuracy is directly related to the accuracy of the data. However. the accuracy is questionable due to skin movement. deformation of skeletal structure while in motion and limitations of commercial motion analysis system . In this study. the ACRS method is applied to an optically-tracked segment marker system. although it can be applied to many of the others as well. In the ACRS method, each marker can be treated independently. as the origin of a local coordinate system for its body segment. Errors, inherent in the experimental process. result in different values for the recovered Euler angles at each origin. By employing knowledge of an initial, calibrated segment reference frame, the Euler angles at each marker location can be averaged. minimizing the effect of the skin extension and rotation. Using the developed ACRS methodology the error is reduced when compared to the general Euler angle method commonly applied in motion analysis. If there is no error exist in the experimental gait data. the separation and Penetration distance of the femoraltibial joint using absolute coordinate system is supposed to be zero during one gait cycle. The separation and Penetration distance was ranged up to 18 mm using general Euler angle method and 12 mm using the developed ACRS.