• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.3
• /
• pp.245-248
• /
• 2020

The wettability of silicon carbide (SiC) crystal, which has 6H-SiC and 4H-SiC regions prepared using the physical vapor transport (PVT) method, is quantitatively analyzed using dispensed deionized (DI) water droplets. Regardless of the polytypes in SiC, the average of five contact angle measurements showed a difference of about 6° between the Si-face and C-face. The contact angle on the Si-face (C-face) is measured after the removal of the native oxide using BOE (6:1), and revealed a significant decrease of the contact angle from 74.9° (68.4°) to 47.7° (49.3°) and from 75.8° (70.2°) to 51.6° (49.5°) for the 4H-SiC and 6H-SiC regions, respectively. The contact angle of the Si-face recovered over time during room temperature oxidation in air; in contrast, that of the C-face did not recover to the initial value. This study shows that the contact angle is very sensitive to SiC surface polarity, specific surface conditions, and process time. Contact angle measurements are expected to be a rapid way of determining the surface polarity and wettability of SiC crystals.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.7
• /
• pp.85-93
• /
• 2003

Droplet vaporization at various ambient pressures is studied numerically by formulating one dimensional evaporation model in the mixture of hydrocarbon fuel and air. The ambient pressure ranged from atmospheric conditions to the supercritical conditions. The modified Soave-Redlich-Kwong state equation is used to account for the real gas effects in the high pressure condition. Non-ideal thermodynamic and transport properties at near critical and supercritical conditions are considered. Some computational results are compared with Sato's experimental data for the validation of calculations. The comparison between predictions and experiments showed quite a good agreement. The droplet lifetime increases with increasing pressure at temperature lower than the critical temperature, however, it decreases with increasing pressure at temperature higher than the critical temperature. The solubility of nitrogen can not be neglected in the high pressure and it becomes higher as the temperature and the pressure go up.

• Journal of the Korean institute of surface engineering
• /
• v.37 no.6
• /
• pp.360-365
• /
• 2004

Ti$_3$SiC$_2$ material was synthesized via the powder metallurgical route, and oxidation tested between 900 and $1200^{\circ}C$ in air for up to 100 hr. The oxidation of $Ti_3$$SiC_2$ material resulted in the formation of $TiO_2$and $SiO_2$, accompanying the evolution of CO or $CO_2$ gases from the initial stage of oxidation. The oxidation resistance of $Ti_3$$SiC_2$ mainly owes the protectiveness of highly stoichiometric $SiO_2$. During the initial stage of oxidation, the dominant reaction was the inward transport of oxygen into the matrix. As the oxidation progressed, an outer $TiO_2$ layer and an inner ( $TiO_2$ + $SiO_2$) mixed layer formed. Between these layers and inside the oxide scale, numerous fine voids formed. Numerous, fine oxide grains formed at $900^{\circ}C$ developed into the outer coarse $TiO_2$ grains and an inner fine ($TiO_2$ + $SiO_2$) mixed grains at the higher temperatures. The oxidation resistance of$ Ti_3$SiC$_2$ progressively deteriorated as the oxidation temperature increased, forming thick scales above $1000^{\circ}C$. The outer coarse $TiO_2$ grains formed above $1100^{\circ}C$ grew rapidly mainly along (211).

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.273-273
• /
• 2002

Masan barber was situated in S.Korean southern central coast. And it is contributing greatly in S.korea's economy development to international trading port of Heaven's blessing that possess natural, geographical situation. Also, because there are Masan free tax area and chanwon heavy industrial complex, sachon air industrial complex etc. on back, it is important permanency in our country. Specially, because inland transport routes such as southern highway, Guma highway and national road system are developed well, the importance is very high. Masan harbor 1899.05.01 be that opened, the 1st and 2nd (central pier) was build 1938∼1944 year, and the 3rd pier was 1973∼1978 year. the 4th pier was 1974∼1983 year, 5th pier was 1984∼1988, 6th pier (west pier) was 1985∼1992 year. it was developed over 100 years. But, it did great many harbor and bay development of last 100 yens but research about coastline change and seashore reclamation is insufficient. Therefore, this research executed research about coastline change of Masan bay of last 100 years, In this study, we analyzed aerial photographs and tide data for the past 100 years using digital aerial photo analysis and GIS techniques for each 3-year interval. We abstracted beach DEM (digital elevation model) and ortho aerial photographs, and conducted a space analysis. As a result, we were able to identify changes in the area As a result, we drew 10 years cycle coastline change of Masan bay. and we can detect bay coastal line change and calculate refill rate.

• International Journal of Highway Engineering
• /
• v.18 no.1
• /
• pp.119-129
• /
• 2016

PURPOSES : The purpose of this study is to develop a methodology for estimating additional carbon emissions due to freeway incidents. METHODS : As our country grows, our highway policy has mainly neglected the environmental and social sectors. However, with the formation of a national green growth keynote and an increase in the number of people interested in environmental and social issues, problems related to social issues, such as traffic accidents and congestion, and environmental issues, such as the impact of air pollution caused by exhaust gases that are emitted from highway vehicles, are beginning to be discussed. Accordingly, studies have been conducted on a variety of environmental aspects in the field of road transport, and for the quantitative calculation of greenhouse gas emissions, using various methods. However, in order to observe the effects of carbon emissions, microscopic simulations must use many difficult variables such as cost, analysis time, and ease of analysis process. In this study, additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service), and the annual additional emissions based on incidents were calculated. According to the results, congestion length and emissions tend to increase with an increase in incident clearance time, number of occupied lanes, and worsening level of service. Using this data, we analyzed accident data on the Gyeong-bu Expressway (Yang-Jae IC - Osan IC) for a year. RESULTS : Additional greenhouse gas emissions that occur because of highway traffic accidents were classified by type (incident handling time, number of lanes blocked, freeway level of service) and annual additional emissions caused by accidents were calculated. CONCLUSIONS : In this study, a methodology for estimating carbon emissions due to freeway incidents was developed that incorporates macroscopic flow models. The results of the study are organized in the form of a look-Up table that calculates carbon emissions rather easily.

• Journal of Advanced Navigation Technology
• /
• v.8 no.2
• /
• pp.98-104
• /
• 2004

When a straight-in landing from an instrument approach using ILS or VOR/DME is not possible or desirable because of topographical reason or bad weather, a circling approach maneuver is initiated by the pilot to align the aircraft with a runway for landing. Visual contact with the runway is necessary while conducting a circle to land maneuver. This research is to develop a new warning system based on a convention marker system which alerts pilots to watch out for exceeding the circling approach area. The airborne system also uses the same receiver unit without any new installations. The objective of this research is to design and develop a Yagi antenna in a special form. The research includes computer simulations to determine the size of antenna radiation pattern and to compute an expected flight path in case of alarm to validate effectiveness of the system.

• Journal of Korea Port Economic Association
• /
• v.32 no.1
• /
• pp.59-77
• /
• 2016

This paper reviews the current local logistics policy of the Incheon Metropolitan City and prioritizes policy agenda based on fuzzy AHP and IPA (Importance Performance Analysis). The analysis recommends that the city needs to keep up the current good works at the policy agenda such as early expansion of the international logistics hub and improvement of the provincial highway network.The policy agenda including the logistics parks, the transport networks and the hinterland activities are evaluated as overkilled agenda. Revitalization of the logistics database, establishment of an integrated business support center, modal shift, and public logistics support were classified as low-priority policy agenda. The policy agenda of urgent concentration includes development of new logistics business and air cargo industry.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.3
• /
• pp.517-526
• /
• 2011

Soil structure plays an important role in ecological system, since it controls transport and storage of air, gas, nutrients and solutions. The study of soil structure requires an understanding of the interrelations and interactions between the diverse soil components at various levels of organization. Investigations of the spatial distribution of pore/particle arrangements and the geometry of soil pore space can provide important information regarding ecological or crop system. Because of conveniences in image analyses and accuracy, these investigations have been thrived for a long time. Image analyses from soil sections through impregnated blocks of undisturbed soil (2 dimensional image analyses) or from 3 dimensional scanned soils by computer tomography allow quantitative assessment of the pore space. Image analysis techniques can be used to classify pore types and quantify pore structure without inaccurate or hard labor in laboratory. In this paper, the last 50 years of the soil image analyses have been presented and measurements on various soil scales were introduced, as well. In addition to history of image analyses, a couple of examples for soil image analyses were displayed. The discussion was made on the applications of image analyses and techniques to quantify pore/soil structure.

• International Journal of Computer Science & Network Security
• /
• v.21 no.9
• /
• pp.323-331
• /
• 2021

The relevance of the study implies the need to explain the main determinants of environmental policy, allowing countries to converge on a common working basis. The purpose of the research is to explore ways in which the environmental aspects of EU regions and territories can be shaped to apply to domestic environmental policy. A total of 997 representatives from the Ukrainian UTCs, who are involved in local environmental policy, participated in the survey. Results of the research. A hierarchy of regional environmental policy objectives has been identified. Three key principles of eco-policy development have been distinguished. The means of the innovative approach strategy implementation have been outlined (formation of the regional market of environmental services; organization of interaction between environmental agencies and market structures; establishment of environmental funds which finance environmental activities; implementation of the "collateral return" system; formation of a system of benefits and loans to enterprises that successfully implement the environmental policy). The means of the prognostic approach implementation strategy to the development of the region's environmental policy have been determined (the use of an orderly and successful long-term strategy of economic development of the region; obligatory consideration in the mechanisms strategy aimed at improvement of environmental management system of the region, interbranch impact of the projects implemented on the region's ecological situation; taking into consideration the economic and geographical peculiarities of the region, the necessary infrastructure, issues of the territorial location of the large enterprises in the region and their impact on the environment). The means of the traditional approach strategy implementation have been outlined (activity programs focused on solution of specific problems, rather than on the implementation of measures for environmental restoration and enhancement; nature conservation problems have interbranch, interdepartmental character due to unity of the region's ecosystem; tracking complexity of changing conditions (water basins, woodlands, air-mass transport), regional boundaries generally do not coincide with natural ecosystems boundaries). The practical significance of the study lies in providing recommendations for the implementation of certain aspects of Ukrainian UTC's environmental policy.

• Journal of Convergence for Information Technology
• /
• v.9 no.2
• /
• pp.7-16
• /
• 2019

The purpose of this study is to identify the characteristics of researches that have been conducted for the last 20 years through analyzing global research trends and evolutions of design articles from 1999 to 2018 with keyword network analysis. For this purpose, we selected 3,569 articles in 22 journals related to design research retrieved from the Scopus database and constructed keyword network model through the author keyword and index keyword. The frequency of the author and index keyword, the centrality of betweenness and degree were analyzed with the keyword network. The results show that design has been applied to various fields for recent 20 years, and the research trends of design could be quantitatively characterized by keyword network analysis. The result of this study could be used to suggest future research topics in the field of design based on quantitative and empirical data.