• Korean Architects
• /
• no.11 s.164
• /
• pp.12-17
• /
• 1982

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1992.06a
• /
• pp.688-692
• /
• 1992

• The Journal of Society for e-Business Studies
• /
• v.5 no.2
• /
• pp.1-25
• /
• 2000

The utilization of Internet, which started only at the level of advertisement, has been gradually expanding its application areas as the trial commercial transaction becomes successful, the password-coding technology which removes the risks on the cyber transaction develops, the electronic money appears and other various related technologies progress. Following this trend the securities industry has been experiencing changes along with efforts to use it commercially. This study is to analyze the work of cyber securities companies on the basis of the theoretical background through preceding studies and literature and also analyze the common and different reasons for superiority-securing strategy in competition along with problems and their reasons. And also the objective of this study is to offer new superiority-securing strategy in competition and problem-solving strategy.

• Proceedings of the Korea Database Society Conference
• /
• 2000.11a
• /
• pp.289-296
• /
• 2000

The utilization of Internet, which started only at the level of advertisement, has been gradually expanding its application areas as the trial commercial transaction becomes successful, the password-coding technology which removes the risks on the cyber transaction develops, the electronic money appears and other various related technologies progress. Following this trend the securities industry has been experiencing changes along with efforts to use it commercially. This study is to analyze the work of cyber securities companies on the basis of the theoretical background through preceding studies and literature and also analyze the common and different reasons for superiority-securing strategy in competition along with problems and their reasons. And also the objective of this study is to offer new superiority-securing strategy in competition and problem-solving strategy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.66-73
• /
• 2020

In the hydrogen compression cycle, which is currently being developed, hydrogen is compressed to a very high pressure using a compressor, and then stored and used in a high-pressure vessel. This shows that an increase in the temperature of hydrogen in the vessel due to a pressure rise during the filling process and the pressure fatigue due to the repeated cycle may cause problems in the reliability of the vessel. In this paper, for the entire processes in a 50 MPa hydrogen compression system, theoretical and numerical methods were conducted to analyze the following: the temperature increase of hydrogen in the vessel and the time required to reach thermal equilibrium with the surroundings, the change in temperature of hydrogen passing through the pressure reducing valve, and the required capacity of the heat exchanger for cooling the vessel. The results will be useful for the design and construction of hydrogen compression systems, such as hydrogen charging stations.

• Journal of the Korean Wood Science and Technology
• /
• v.38 no.3
• /
• pp.230-241
• /
• 2010

The purpose of this study was to seek the optimum condition for effective separation of the chemical constituents of wood biomass by means of hydrolysis of acetone solution in presence of acid salt as a catalyst. Out of diverse acid salts the catalytic effect of aluminum sulfate ($Al_2(SO_4)_3$) was the most excellent during the hydrolysis of wood biomass in the acetone solution and the optimum concentration was 0.01 M (6.3 wt%). In the condition of mixture ratio of acetone and water to 9 : 1 as well as optimum concentration of aluminum sulfate two wood biomass species, oak wood (Quercus mongolica Fischer) and Pine wood (Pinus densiflora Sieb. et Zucc.), was hydrolyzed for 45 minutes at $200^{\circ}C$ and the degree of hydrolysis was determined to 92.7% and 92.4%, respectively. Extending the reaction time to 60 minutes in the mixture ratio of acetone and water to 8 : 2 the degree of hydrolysis of oak wood was also ca. 92.7%. In the case of Pinus, however, the similar hydrolysis ratio was obtained at $210^{\circ}C$. As the temperature and hydrolysis time increased, the quantitative amount of lignin recovered from the hydrolysate clearly increased, whereas the total amount of carbohydrates in the hydrolysate decreased rapidly. Considering the recoverable amount of lignin and carbohydrate in the hydrolysate, the best condition for the hydrolysis of wood biomasses were confirmed to the mixture ratio of acetone and water to 8 : 2, the concentration of aluminum sulfate of 6.3 wt%, hydrolysis temperature of $190^{\circ}C$ for 60 minutes. In this condition the total amounts of carbohydrate in the hydrolysates of oak wood and pine wood were estimated to 47.6% and 51.4%, respectively. The amount of lignin recovered from the hydrolysates were ca. 18.2% for oak wood and 13.7% for pine wood.