• Journal of IKEEE
• /
• v.26 no.2
• /
• pp.249-256
• /
• 2022

The prosthetic leg is a device that performs walking instead of a amputated lower limb, and require a change in locomotion mode by providing the user's intention to respond to a discontinuous locomotion environment. Research has been conducted to detect the users' intentions through biomechanical features inside the socket that directly contacts the cut site in demand for natural locomotion mode changes without external control equipment. However, there is still a need for a sensor system that is suitable for the internal environment of the main body and socket of the cut site. Accordingly, this paper proposed a film-type sensor system that is suitable for the main body characteristics of the cut site, is not affected by the temperature and humidity conditions inside the socket, and is easy to manufacture in various sizes. The proposed sensor is manufactured base on Velostat film and takes into account the pressure measurement characteristics that vary with size. Through the experiment, the change in the internal pressure of the socket due to the intentional posture performance of the wearer was measured, and the possibility of detecting the intention to change the locomotion mode was confirmed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.445-450
• /
• 2011

Swirling flows inside a swirl mixing chamber are investigated for simple configuration where swirl is produced by a tangential entry type swirl generator. The flow downstream of the swirl generator has been quantified by measurements two velocity components and their corresponding mean values along axial and radial direction using Particle Image Velocimetry(PIV). The mass flow rate of the tangential entry is increased in order to study their effect on the flow field. From the measurement profile of velocity and vorticity, flow mixing characteristics in a swirl mixing chamber are evaluated.

• Journal of Environmental Science International
• /
• v.8 no.1
• /
• pp.45-50
• /
• 1999

Four cast iron pipe sections containing 3 styrene butadiene rubber (SBR) gaskets (1 joint and 2 end caps) were filled with water and maintained at approximately 40 psi internal pressure. The pipe sections were placed inside 16 gallon drums filled with initially clean sand. Three of the tanks were subsequently contaminated with gasoline, gasoline spiked with pyrene and naphthalene, and toluene. The forth tank served as a control. The water inside each pipe was monitored over time for organic chemical contamination. Permeation of organic chemicals into the water inside the pipe systems was found to occur in all 3 contaminated pipe systems after approximately 100 days as measured organic chemicals concentrations were significantly above those in the uncontaminated cell. Flushing experiments in which the water inside the contaminated pipes was replaced with initially clean water showed that organic chemical concentrations inside the pipe rapidly (12 days) reached their preflushing levels.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.6 no.1
• /
• pp.31-36
• /
• 2000

180g of fermented soy paste and 150g of red pepper paste were packaged in glass jars of 232 mL with different conditions of active packaging and then stored at $13^{\circ}C$ for about 170 and 128 days, respectively. During the storage, package atmosphere, surface color, pH, acidity and microbial flora were monitored to see the effect of packaging conditions. Test packaging conditions include package equipped with $Ca(OH)_2\;as\;CO_2$ absorber, package with pinhole and closed control one. Closed control packages of soypaste and red pepper paste showed the increased $CO_2$ partial pressure, the decreased $O_2$ partial pressure and the constant $N_2$ partial pressure to produce high pressure buildup with storage. The paste packages with $Ca(OH)_2$ maintained relatively low $CO_2$ partial pressure and thus the package pressure close to normal atmospheric pressure for initial storage period of 70 days. The packages with air pinhole channel had the partial pressures of $O_2\;and\;N_2$ decreased with storage time, while $CO_2$ partial pressure first increased to a maximum and then slowly decreased thereafter Without any pressure increase the packages with pinhole gave the lowest quality changes possibly due to the effect of package atmosphere, but it had problem of mold contamination and growth for soy paste after 120 days. There were no difference in microbial flora between the packages after about 70 day storage.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.505-508
• /
• 2008

Concrete is a type of porous materials and is physically and chemically damaged due to exposure to various environments from the placing to the service life. These reactions affect the corrosionof steel bars applied in concrete and that decreases the durability life and strength of such steel bars. Thus, it is very important to insert rust inhibitors into steel bars in the case of a deterioration element that exceeds the critical amount of corrosion in the location of steel bars. However, it is very difficult to guarantee corrosion resistance at the location of steel bars using conventional technology that applies corrosion inhibitors only on the surface of concrete. This study attempts to develop a method that penetrates corrosion inhibitors up to the location of steel bars and investigate the penetration depth of corrosion inhibitors by verifying moisture migration in concrete under an applied pressure.

• Korean small business review
• /
• v.42 no.4
• /
• pp.173-212
• /
• 2020

Interest in sustainable management based on the stakeholder perspective is expanding not only within an organization but also across the supply chain. For large companies that have established networks, sustainability management of the supply chain is now a factor that not only determines the social performance of the company as a whole, but also determines its long-term competitive position. Despite these changes in the business world, especially the proliferation of the sustainable supply chain management (SSCM) system, systematic research on SSCM has been lacking. In particular, there was a lack of empirical analysis on which factors promoted the establishment of the SSCM system for large companies and what's the effects of SSCM. In this regard, this study analyzes i) the impact of the social responsibility pressure of customers as external stakeholders and the CSR orientation of purchasing managers as internal stakeholders on supply chain transparency and partnership cooperation respectively, and ii) whether supply chain transparency and partnership cooperation can enhance corporate reputation. The samples used in this study were 69 large companies representing Korea. The results showed that the social responsibility pressure of customers and the purchasing manager's CSR orientation were positively related to the transparency of the supply chain. However, for partnership cooperation, only the purchasing manager's CSR orientation was found to have a positive and significant effect. Meanwhile, both supply chain transparency and partnership cooperation were positively related to the corporate reputation. At the end of the study, discussions on the implications of the results and future research directions will be presented.

• 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.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.34-34
• /
• 1999

토카막(Tokamak)에서는 플라즈마(plasma)로 불순불(impurity)의 유입을 방지하기 위해 고진공을 유지해야 하며 이를 위해 가열탈리(backing), 방전세정(discharge codanning) 등 wall conditioning이 기본적으로 요구된다. KT-1 토카막은 실험실 이전에 따른 해체로 인해 진공용기(vacuum vessel) 가 대기압 하에 수개월 동안 노출되어 있었기 때문에 재조립 후 가열 탈 리가 필수적이나 진공용기의 외부에 saddle loop coil을 비롯해 Rogowski, diamagnetic coil, poloidal field coil 등 많은 magnetic pick up coil 들이 설치되어 있어 열선 등 일반적인 방법으로 가열 탈 리가 어려운 상황이다. 따라서 KT-1 토카막에서는 전자석 코일에 상전원을 부가하였을 때 진공용기에 발생하는 유도가열 (inductive heatin)을 이용해 가열 탈리를 시도하였다. 유도 가열 탈리(inductive backing)는 토로이달 자장 코일(toroidal field coil)과 가열 저장 모일(ohmic heating coil)을 각각 이용하여 코일의 온도가 6$0^{\circ}C$ 이하가 유지되는 코일 전류 범위내에서 수행하였으며 먼저 이 둥 경우에 있어서 진공용기의 온도분포를 비교하엿다. 그리고 가열 탈리 기간 및 그 전, 후의 진공압력과 잔류기체 분압을 측정, 분석하였다. 유도가열에 의한 방법으로 KT-1 토카막에서 얻은 탈리온도는 12$0^{\circ}C$정도로 비교적 낮았으나 탈리 시간을 연장하여 탈리효과를 어느 정도 보상할 수 있으며 일반적인 가열 탈리가 여려운 경우 유도 가열 탈 리가 채택될 수 있는 또 하나의 방법이라 볼 수 있다.

• Journal of the Korean Society for Railway
• /
• v.14 no.2
• /
• pp.143-150
• /
• 2011

This paper presents a preliminary study for air-tightness evaluation of vacuum tube structures for super-speed tube railway systems. The formula for flow rate of the air caused by the pressure difference of the inside and outside of the tube structure is derived based on Darcy's law. A test is then performed to measure the air-permeability of concrete with various compressive strengths, the result of which is used for analytical simulation of the air intrusion for a tube structure with a preliminarily defined section. It has been shown that concrete with the compressive strength of at least more than 50MPa is recommended for effective operation and maintenance of the vacuum pump systems, as the air-permeability of concrete is inversely proportional to the exponent of its compressive strength.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.123-133
• /
• 2023

Commercial hydrogen fuel cell vehicles are charged by compressing gaseous hydrogen to high pressure and storing it in a storage tank in the vehicle. This process causes the temperature of the gas to rise, to ensure the safety to storage tanks, the temperature is limited. Therefore, a heat transfer model is needed to explain this temperature rise. The heat transfer model includes the convective heat transfer phenomenon, and accurate estimation is required. In this study, the convective heat transfer coefficient in the hydrogen fueling process was calculated and compared using various correlation equations considering physical phenomena. The hydrogen fueling process was classified into the fueling line from the dispenser to the tank inlet and the storage tank in the vehicle, and the convective heat transfer coefficients were estimated according to process parameters such as mass flow rate, diameter, temperature and pressure. As a result, in the case of the inside of the filling line, the convective heat transfer coefficient was about 1000 times larger than that of the inside of the storage tank, and in the case of the outside of the filling line, the convective heat transfer coefficient was about 3 times larger than that of the outside of the storage tank. Finally, as a result of a comprehensive analysis of convective heat transfer coefficients in each process, it was found that outside the storage tank was lowest in the entire hydrogen fueling process, thus dominated the heat transfer phenomenon.