• Journal of the Korean Institute of Gas
• /
• v.18 no.5
• /
• pp.33-39
• /
• 2014

Heat transfer oils are used in applications such as chemical plant heating systems, refinery heat exchange systems, certain gas processes, injection molding systems, and pulp and paper processing. These oils are extremely stable and resistant to thermal and oxidative degradation. In the event of a spill or accidental release of heat transfer oils, it can be ignited easily when there is an ignition source. This study discusses the status of safety management through the actual status of the heat transfer oils to prevent fire and explosion accidents in industries for process safety management. The actual status of the heat transfer oils in process system of industries surveyed by a questionnaire developed. The results of this study can be used to help establishment of safety management to prevent fire and explosion accidents, such as the management of heat transfer oils, safe operation and maintenance in heat transfer oil processes.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2208-2218
• /
• 2017

To resolve overload in a distribution system, a distribution system operator (DSO) often performs a load transfer using normally open tie points and switches in the distribution line. During this process, the distribution system is momentarily operated in closed-loop operation. A closed-loop current in the distribution system can cause a power failure due to excess breaking current in the circuit breakers and reclosers. Therefore, it is necessary to calculate the closed-loop current exactly. However, if there are a large number of distributed generation (DG) systems in the distribution system, such as energy storage systems (ESS), they might obstruct the closed-loop operation based on bidirectional power flow. For quick and precise operation of a closed-loop system, the ESS has to regulate the power generation while satisfying closed-loop operation in the worst cases. We propose a strategy for balanced power regulation of an ESS. Simulations were carried out using PSCAD/EMTDC, and the results were compared with calculation results.

• Journal of Wind Energy
• /
• v.14 no.3
• /
• pp.61-68
• /
• 2023

This paper aims to perform optimal operation and maintenance with an integrated monitoring system for offshore wind platforms. Based on the wind direction and wind speed data of existing wind farms, a monitoring system was established along with weather and weather data to maximize the operational efficiency of wind farms. Compared to wind power on land, offshore wind power is difficult to maintain due to weather, logistics and geographical limitations. Therefore, economic analysis of actual operation and maintenance is essential for large-scale offshore wind farms. In this paper, the availability of offshore wind farms was analyzed by using personnel resources, parts inventory, Crew Transfer Vessel (CTV) and Specialized service Operation Vessel (SOV) etc. before the actual operation and maintenance of wind farms. A comparative analysis was conducted to determine the optimum operating efficiency and economical maintenance costs.

• Archives of Reconstructive Microsurgery
• /
• v.5 no.1
• /
• pp.112-120
• /
• 1996

We peformed tendon transfer with a microvascular free flap for recovery of handicapped function and reconstruction for the skin and soft tissue loss. We review the clinical data of 11 children who underwent these operation due to injured foot by pedestrian accident from January, 1986 to June, 1994. The mean age of patients was 5.6 years old(3-8). Five cases underwent tendon transfer and microvascular free flap simultaneously. Another 6 cases underwent operations separately. The time interval between tendon trasnfer and microvascular free flap was average 5.6 months(2-15 months). The duration between initial trauma and tendon transfer was average 9.6 months(2-21 months). The anterior tibial tendon was used in 6 cases. Among these, the technique of splitting the anterior tibial tendon was used in 5 cases. The posterior tibial tendon was used in 3 cases and the extenosr digitorum longus tendon of the foot in 2 cases. Insertion sites of tendon transfer were the cuboid bone in 3 cases, the 3rd cuneiform bone in 3 cases, the 2nd cuneiform bone in 1 case, the base of 4th metatarsal bone in 1 case, and the remnant of the extensor hallucis longus in 3 cases. The duration of follow-up was average 29.9 months(12-102 months). The clinical results were analysed by Srinivian criteria. Nine cases were excellent and 2 cases were good. The postoperative complications were loosening of the tranferred tendon in 2 cases, plantar flexion contracture in 1 case, mild flat foot deformity in 1 case and hypertrophic scar in 2 cases. So we recommend the tendon transfer with a microvascular free flap in the case of injured foot of children combined with nerve injury and extensive loss of skin, soft tissue and tendon.

• Journal of Power System Engineering
• /
• v.10 no.2
• /
• pp.47-53
• /
• 2006

This study concerns the performance of condensation heat transfer in plain and grooved thermosyphons. Distilled water, methanol, ethanol have been used as the working fluids. In the present work, a copper tube of the length of 1200mm and 14.28mm of inside diameter is used as the container of the thermosyphon. Each of the evaporator and the condenser section has a length of 550mm, while the remaining part of the thermosyphon tube is adiabatic section. A study was carried out with the characteristics of heat transfer of the thermosyphon 50, 60, 70, 80, 90 helical grooves in which boiling and condensation occur. The liquid filling as the ratio of working fluid volume to total volume of thermosyphon, the kinds of working fluid, the inclination angle, grooves and operating temperature have been used as the experimental parameters. The experimental results show that the number of grooves, the amount of the working fluid, the kind of working fluid, angle of inclination angle are very important factors for the operation of thermosyphon. The maximum heat transfer was obtained when the liquid fill was about 20 to 25 % of the thermosyphon volume. The relatively high rates of heat transfer have been achieved in the thermosyphon with grooves. The helical grooved thermosyphon having 70 to 80 grooves in water, 60 to 70 grooves in methanol and 70 to 80 grooves in ethanol shows the best heat transfer coefficient in both condensation.

• The Korean Journal of Emergency Medical Services
• /
• v.5 no.1
• /
• pp.177-198
• /
• 2001

The purpose of this research which was conducted by surveying the transfer consultation records from 360 medical institutions such as general hospitals, hospitals, clinics to the Emergency Medical Center at E University Hospital for six months(Jan. 1, 2000 - Jun. 30, 2000) are to standardize & complete transfer consultation record of hospitals at the 1st & 2nd referral level and to give patients transferred emergency medical center medical information services on a better quality. The conclusions and suggestions from this study were summarized as follows; (1) Examing the distribution of the referral medical consultation(transfer) sheet type, surgery part local clinic sheet types were 34.4%, medical part local clinic sheet types were 26.7%, undifferentiated local clinic sheet types were 23.9% and hospital level sheet types were 15.0%. (2) The items of the transfer consultation records had been standardized more than 75% in the order of patient's name, date, doctor's name, diagnosis, patient's status, impressions. (3) That the degree of recording completion on these items is in the order of patient's name, date, diagnosis, impressions was revealed. (4) Because the standardization and the degree of recording completion are very low in the patient's gender, age, address, electronic recording system was needed for more perfect input of initial patient informations. (5) This standardizing & complete recording on examination and medication will prevent re-examination and abuse of medication for patients transferred emergency medical center. (6) EMT Transfer System should be fixed in all medical institute for the standardizing & complete recording on care period and departure time will give many emergency patients the proper treatments at the proper time. (7) It was revealed that developing new standardized transfer consultation record & using electronic recording system are needed. (8) The complete recording & Fast Track System were needed for higher rate of bed operation at emergency medical center and more hospital profit.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.896-901
• /
• 2009

In this study, in order to apply the air and pure oxygen in the Jet Loop Reactor (JLB) in which the oxygen transfer rate is high, differentiate the operation mode according to each air flowrate and liquid flowrate and investigate the oxygen transfer characteristic, an experiment was carried out. The oxygen concentration with the air flowrate ($Q_g$) and liquid flowrate ($Q_L$) was identical but the oxygen transfer coefficient ($K_L{\cdot}a$) is linear depending on degree of two factors. The width of an increase is small in $0.1min^{-1}$ when the air flowrate is 0.2 L/min with increasing the liquid flowrate. Whereas, the increment was exposed to be very high for $1.5min^{-1}$ when the air flowrate was 5 L/min. In the experiments using the pure oxygen, it was 30 mg/L of oxygen concentration finally and it was 3.5 times than using the air. But the time reached the saturated concentration was similar to using the air, and $K_L{\cdot}a$ was similar to using the air too. Analysis between two independent variable and oxygen transfer of the correlation is the same model like $K_L{\cdot}a={0.0161Q_L}^{1.5371}{Q_g}^{0.5433}$ using with coefficient non linear regression analysis. It was resulted that the liquid flowrate were approximately three times than air flowrate on effect to oxygen transfer rate.

• 전자공학회논문지 IE
• /
• v.47 no.2
• /
• pp.47-53
• /
• 2010

The purpose of this paper is to build on automatic system for the shot ball transfer hoist. The shot ball is used to remove completely paint or leftovers before spreading the new paint on a large vessels surface. The shot ball is made of melted iron through cooling process, and it is transferred to hopper by electromagnet of hoist. Currently, the transfer process of the shot ball is performed by manual operation, and the transfer process is inefficient. So we have developed an automatic system to replace the manual system. The developed automation systems have efficient and accurate position control performance.

• Journal of computational fluids engineering
• /
• v.13 no.3
• /
• pp.21-27
• /
• 2008

The reactor head of a sodium-cooled fast reactor KALIMER-600 should be cooled during the reactor operation in order to maintain the integrity of sealing material and to prevent a creep fatigue. Analyzing turbulent natural convection flow in the cover gas region of reactor vessel with the commercial CFD code CFX10.0, the cooling requirement for the reactor head and the performance of the insulation plate were assessed. The results showed that the high temperature region around reactor vessel was caused by the convective heat transfer of Helium gas flow ascending the gap between the insulation plate and the reactor vessel inner wall. The insulation plate was shown to sufficiently block the radiative heat transfer from pool surface to reactor head to a satisfactory degree. More than $32.5m^3$/sec of cooling air flow rate was predicted to maintain the required temperature of reactor head.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.1
• /
• pp.14-24
• /
• 2011

In order to facilitate the electricity market operation and trade in the restructured environment, ample transmission capability should be provided to satisfy the demand of increasing power transactions. The conflict of this requirement and the restrictions on the transmission expansion in the restructured electricity market has motivated the development of methodologies to enhance the available transfer capability (ATC) of existing transmission grids. The insertion of flexible AC transmission System (FACTS) devices in electrical systems seems to be a promising strategy to enhance single area ATC and multi-area ATC. In this paper, the viability and technical merits of boosting single area ATC and multi-area ATC using Thyristor controlled series compensator (TCSC), static VAR compensator (SVC) and unified power flow controller (UPFC) in single device and multi-type three similar and different device combinations are analyzed. Particle swarm optimization (PSO) algorithm is employed to obtain the optimal settings of FACTS devices. The installation cost is also calculated. The study has been carried out on IEEE 30 bus and IEEE 118 bus systems for the selected bilateral, multilateral and area wise transactions.