• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.3
• /
• pp.62-80
• /
• 2021

The requirements for the next-generation propulsion system and for a good propellant have been summarized. The characteristics and effectiveness of kerosene, hydrogen, and methane, which are the fuels that are mainly attracting attention in Korea and abroad, were compared with each other. As a result of the comparison, methane was evaluated to be more advantageous than other fuels in reliability, cost, reusability, maintenance, eco-friendliness, safety, lifespan, technical difficulties, engine cycle selection, application of common bulkhead, and non-disassembly/reassembly delivery. And in terms of performance, the specific impulse of methane is higher than that of kerosene, so the efficiency of the launch vehicle can be increased. Methane's properties incluidng eco-friendliness, low-temperature combustion, long life, and maintenability make it beneficial for reuse and for the development of multi-purpose engines.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.2
• /
• pp.119-143
• /
• 2021

Selecting liquid methane as fuel is a prevailing trend for recent rocket engine developments around the world, triggered by its affordability, reusability, storability for deep space exploration, and prospect for in-situ resource utilization. Given years of time required for acquiring a new rocket engine, a national-level R&D program to develop a methane engine is highly desirable at the earliest opportunity in order to catch up with this worldwide trend towards reusing launch vehicles for competitiveness and mission flexibility. In light of the monumental cost associated with development, fabrication, and testing of a booster stage engine, it is strategically a prudent choice to start with a low-thrust engine and build up space application cases.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.3
• /
• pp.54-65
• /
• 2022

We are developing a compact ignition device that can provide a multi-ignition capability for an upper stage methane engine of a two staged small satellite launch vehicle. Firstly, the multi-ignition device is designed and built as an integral part of an additively manufactured mixing head. Secondly, the ignition device requires no separate high-pressure vessels to store ignition propellants as they are branched out from the main feed lines for the mixing head. We performed experiments at various levels, including igniter autonomous tests, thrust chamber ignition and combustion tests on the new compact ignition device which is integrated in the thrust chamber of one-tonf class liquid oxygen/liquid methane engine, and confirmed stable ignition performance.

• Composites Research
• /
• v.37 no.1
• /
• pp.32-39
• /
• 2024

Solid-state hydrogen storage is gaining prominence as a crucial subject in advancing the hydrogen-based economy and innovating energy storage technology. This storage method shows superior characteristics in terms of safety, storage, and operational efficiency compared to existing methods such as compression and liquefied hydrogen storage. In this study, we aim to evaluate the solid hydrogen storage performance on the nanotube surface by various structural design factors. This is accomplished through molecular dynamics simulations (MD) with the aim of uncovering the underlying ism. The simulation incorporates diverse carbon nanotubes (CNTs) - encompassing various diameters, multi-walled structures (MWNT), single-walled structures (SWNT), and boron-nitrogen nanotubes (BNNT). Analyzing the storage and effective release of hydrogen under different conditions via the radial density function (RDF) revealed that a reduction in radius and the implementation of a double-wall configuration contribute to heightened solid hydrogen storage. While the hydrogen storage capacity of boron-nitrogen nanotubes falls short of that of carbon nanotubes, they notably surpass carbon nanotubes in terms of effective hydrogen storage capacity.

• Journal of Korea Technology Innovation Society
• /
• v.12 no.4
• /
• pp.788-818
• /
• 2009

Renewable energy refers to solar energy, biomass energy, hydrogen energy, wind power, fuel cell, coal liquefaction and vaporization, marine energy, waste energy, and liquidity fuel made out of byproduct of geothermal heat, hydrogen and coal; it excludes energy based on coal, oil, nuclear energy and natural gas. Developed countries have recognized the importance of these energies and thus have set the mid to long term plans to develop and commercialize the technology and supported them with drastic political and financial measures. Considering the growing recognition to the field, it is necessary to analysis up-to-now achievement of the government's related projects, in the standards of type of renewable energy, management of sectional goals, and its commercialization. Korean government is chiefly following suit the USA and British policies of developing and distributing renewable energy. However, unlike Japan which is in the lead role in solar rays industry, it still lacks in state-directed support, participation of enterprises and social recognition. The research regarding renewable energy has mainly examinedthe state of supply of each technology and suitability of specific region for applying the technology. The evaluation shows that the research has been focused on supply and demand of renewable as well as general energy and solution for the enhancement of supply capacity in certain area. However, in-depth study for commercialization and the increase of capacity in industry followed by development of the technology is still inadequate. 'Cost-benefit model for each energy source' is used in analysis of technology development of renewable energy and quantitative and macro economical effects of its commercialization in order to foresee following expand in related industries and increase in added value. First, Investment on the renewable energy technology development is in direct proportion both to the product and growth, but product shows slightly higher index under the same amount of R&D investment than growth. It indicates that advance in technology greatly influences the final product, the energy growth. Moreover, while R&D investment on renewable energy product as well as the government funds included in the investment have proportionate influence on the renewable energy growth, private investment in the total amount invested has reciprocal influence. This statistic shows that research and development is mainly driven by government funds rather than private investment. Finally, while R&D investment on renewable energy growth affects proportionately, government funds and private investment shows no direct relations, which indicates that the effects of research and development on renewable energy do not affect government funds or private investment. All of the results signify that although it is important to have government policy in technology development and commercialization, private investment and active participation of enterprises are the key to the success in the industry.

• Applied Chemistry for Engineering
• /
• v.17 no.4
• /
• pp.361-368
• /
• 2006

The purpose of this study is to invent the preparation technique of the foam-floater used as a level gauge of liquefied petroleum gas (LPG) tank under high pressure, which has not only closed pores but also has under 5 wt% changingrate in case of depositing 72 h in room-temperature LPG. In pressure-resistance and deposition experiment, the prepared foam-floaters with different sulfur (325 Mesh and 400 Mesh) and foaming agent (dinitrosopentamethylenetetramin; DPT and azodicarbonamide; AC) had a marginal difference in its weight changing-rate. However, the prepared floater with sulfur 400 Mesh and the foaming agent AC had smaller pores and higher closed pore-rate. Under $50kg_f/cm^3$ hydraulic pressure, the floater with medium thermal (MT) carbon showed a lower weight changing-rate than semi reinforcing furnace (SRF) carbon. Providing a post-treatment to the prepared floater, the hardness and the pressure-resistance of the inner pore-wall of floater were increased. Prepared floaters having a specific gravity below 0.30 were distorted and broken, and other floaters with a specific gravity above 0.35 were not useful as a floater because of the low buoyancy. Therefore, it was considered that the floaters with a specific gravity between 0.3~0.35 are the most useful as a floater under $50kg_f/cm^3$ pressure-resistance.

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.1
• /
• pp.99-105
• /
• 2013

In this paper, we carried out the basic design of 36 MTD natural gas BOG re-liquefaction system to recover the generated natural gas during performance test of LNG pump and natural gas compressor. The re-liquefaction process of natural gas is designed to have 1500 kg/h of liquefaction rate with reverse Brayton refrigeration cycle. With the designed process, the variation of liquefaction rate is calculated for various inlet conditions of feed gas. From results, the liquefaction rate is more sensitive for inlet temperature than gas composition. The specifications of equipments such as gas blower, natural gas compressor, cryogenic heat exchanger and nitrogen compander are determined on the basis of the designed process. The requirement of power consumption and cooling water are also determined through the basic design.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.2
• /
• pp.689-696
• /
• 2017

The practical applications of ordinary high-fluidity concrete have been limited due to several drawbacks, such as high hydration heat, high amount of shrinkage, and non-economic strength development. On the other hand, due to its advantages, such as improvement of construction quality, reduction of construction cost and period, the development of high-fluidity concrete is a pressing need. This study examined the properties of high-fluidity concrete, which can be manufactured on the low binders using a viscosity agent to prevent the segregation of materials. The optimal viscosity agent was selected by an evaluation of the mechanical properties of high-fluidity concrete among six viscosity agents. The acrylic type and urethane type viscosity agents showed the best performance within the range where no material separation occurred. The mechanical properties were evaluated to examine the optimal amount of AC and UT viscosity agent added by mixing two viscosity agents according to the adding ratio and blending them together with high performance water reducing agent. When the ratio of the AC : UT viscosity agents was 5:5, it was most suited for high-fluidity concrete with low binders by increasing the workability and effect of the reducing viscosity.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.5
• /
• pp.1159-1170
• /
• 2020

In this study, to improve the stability of fermented squalene developed using microorganisms, Microsome-SQ20 was prepared, and its physical behavior, properties, and efficacy were studied. The appearance of Microsome-SQ20 was a transparent liquid, no smell, and had a specific smell. The color was a transparent liquid, and the specific gravity was 0.928 and the pH was 5.82 (20% solution), forming a nano-emulsion suitable for use in cosmetics. It was confirmed that the content of the main component of squalene was 20.05%, which was stably sealed. The particle size measured by 0.1% aqueous solution of Microsome-SQ20 was 134.8 nm to obtain a bluish emulsified phase. The antioxidant effects of F-SQ and MF-SQ by DPPH radicals were 80.72% and 81.5%, respectively, showing superior effects compared to L-ascorbic acid. The cell viability of squalene (SQ), fermented squalene (F-SQ) and microsome squalene (MF-SQ) was at 10 ppm, respectively, showing 121.2%, 150.3%, and 129.9% cell viability. It was found that SQ, F-SQ, and MF-SQ had an elastase inhibitory ability of 8.7%, 10.33% and 8.7% at 10 ppm, respectively. In addition, the inhibitory ability of MMP-1 was 1.55%, 41.44%, 31.79% at 10 ppm for SQ, F-SQ, and MF-SQ, respectively, indicating that F-SQ significantly reduced the MMP-1 expression.

• Journal of Energy Engineering
• /
• v.29 no.1
• /
• pp.13-24
• /
• 2020

Many countries are actively engaging in the reduction of greenhouse gas emissions, and as part of this effort, gradually reducing the portion of coal power generation and instead increasing the portion of power generations from renewable energy sources and natural gas. Korea is taking a similar policy to expand LNG power generation for the next decade. There is a concern, though, about the policy not being aligned with the domestic industry development, since only a few products are being made in Korea along the LNG power generation industry value chain. Therefore in this paper, we first looked at the current status of the gas turbine and high temperature parts industry used for LNG power generation in Korea, and then looked into the industrial issues and challenges through the analysis of supply chains of the domestic gas turbine industry. Finally, we tried to propose strategies to revitalize and localize the domestic gas turbine and high temperature parts industry. The proposed strategies can be summarized as 1) creation of domestic gas turbine manufacturing ecosystem via construction of gas turbine alliance, 2) strategic R&D support for localization of gas turbine and high temperature parts, and 3) provision of domestic testbeds for technology evaluation and commercialization.