• Journal of the Korean Society of Safety
• /
• v.32 no.6
• /
• pp.22-28
• /
• 2017

According to the National Fire Data System (NFDS), more than 5,000 vehicle fires have occurred every year for the last 10 years. Vehicle fires are primarily caused by mechanical (breaking system and engine), electrical (wiring and battery), and chemical (oil and fuel gas leakage) problems. The electrical factor has increased with the installation of driver convenience equipment. For example, today, the black box is widely used to provide video data recording of motor vehicle accidents. The black box consists of a front camera, rear camera, and wires. The black box wires are directly connected to the junction box or fuse box from the start battery that operates to provide normal on power supplying for engine stop. It is extremely dangerous when the wires short circuit due to insulation aging, mechanical and electrical stress, etc. In this study, the black box wiring fire risk have been analyzed and investigated when the steady state and abnormal operations, and under the following conditions: wiring arrangements with a high temperature condition, insulation aging, poor contact, and short circuits. The results showed that black box wiring short circuits had a higher fire risk than the other fire hazard elements. To prevent fire hazards caused by black box wiring, the black boxes must be installed by qualified service personnel. Do not modify the wiring, remove the fuse and secure the wiring using cable ties or insulation tape.

• Journal of the Korean Institute of Gas
• /
• v.10 no.3 s.32
• /
• pp.7-12
• /
• 2006

In this paper, a new evaluation scheme is suggested to estimate load-carrying capacities of wall thinned pipes. At first, computational fluid dynamics analyses employing steady-state and incompressible flow are carried out to determine pressure distributions in accordance with conveying fluid. Then, the variational pressures are applied as input condition of structural finite element analyses to calculate local stresses at the deepest point. The efficiency of proposed scheme was proven from comparison to conventional analyses results and it is recommended to consider the fluid structure interaction effect for exact integrity evaluation.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.4
• /
• pp.414-420
• /
• 2006

Effluent from an anaerobic digestion system with an elutriated phased treatment(ADEPT, Anaeorbic Digestion Elutriated Phase Treatment) for piggery waste treatment using anaerobic ammonium oxidation(ANAMMOX) process was used as a substrate of partial nitrification reactor. In mesophilic condition($35^{\circ}C$), controlling parameters of nitrite accumulation were HRT, pH, free ammonia(FA) and hydroxylamine rather than dissolved oxygen. Bicarbonate alkalinity consumption ratio including bicarbonate stripping and buffering was 8.78 g $Alk._{comsumed}/g\;NH_4-N_{converted}$. In steady state for 1 day of HRT and $2.7{\sim}4.4mg/L$ of DO, $NO_2-N/NH_4-N$ ratio of partial nitrification effluent was about $1{\sim}3$, which was applicable to ANAMMOX reactor influent for the combined partial nitrification-ANAMMOX process.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.1
• /
• pp.1-7
• /
• 2007

Generally, an electric railroad feeding system has many problems due to the different characteristics in contrast with a load of general three-phase AC electric power system. One of them is harmonics problem caused by the switching device existing in the feeding system, and moreover, the time-varying dynamic loads of rail way is inherently another cause to increase this harmonics problem. In Korea power systems, the electric railroad feeding system is directly supplied from the substation of KEPCO. Therefore, if voltages fluctuation or unbalanced voltages are created by the voltage and current distortion or voltage drop during operation, it affects directly the source of supply. The trainloads of electric railway system have non-periodic but iterative harmonic characteristics as operating condition, because the electric characteristic of the electric railroad feeding system is changed by physical conditions of the each trainload. According to the traditional study, the estimation of harmonics has been performed by deterministic way using the steady state data at the specific time. This method is easy to analyze harmonics, but it has limits in some cases which needs an assessment of dynamic load and reliability. Therefore, this paper proposes the probabilistic estimation method, moments matching method(MW) in order to overcome the drawback of deterministic method. In this paper, distributions for each harmonics are convolved to obtain the moments and cumulants of TDD(Total Demand Distortion), and this can be generalized for any number of trains. For the case study, the electric railway system of LAT(Intra Airport Transit) in Incheon International Airport is modeled using PSCAD/EMTDC dynamic simulator. The raw data of harmonics for the moments matching method is acquired from simulation of the LAT model.

• Journal of Nutrition and Health
• /
• v.30 no.9
• /
• pp.1035-1044
• /
• 1997

There is substantial evidence that insulin sensitivity can be enhanced through appropriate dietary management . In this study, insulin sensitivity was evaluated using and insulin suppression test. Male Sprague-Dawley rats, were caused to be in a diabetic condition by the injection of streptozotocin, and divided into four groups. They were fed one of the following diets for 2 weeks : (group 1) a high-carbohydrate(CHO) low-fat low-fiber diet, (group 2) a high CHO low-fat and high-fiber diet, (group 3) a low-CHO high-fat and low-fiber diet, and (group 4) a low-CHO low-fat diet groups (as comparison between group 1 and group 2 shows). In the low-CHO high-fat diet groups, dietary fiber tended to decrease plasma glucose levels at the end of the experiment, but not significantly (as comparison between group 3 and group 4 shows). The average steady state plasma glucose level in rats on the group 3 diet was the highest among all four groups(p<0.05), indicating the poorest insulin sensitivity . However, high fiber increased insulin sensitivity in rats on the low-CHO high-fat diets(as shows by a comparison between group 3 and group 4). On the other hand , the high-CHO low-fat enhanced insulin sensitivity in rats on the low fiber diet(group 1 and group 3). The degree of enhancement of insulin sensitivity depends on the combination of CHO, fat , and fiber in the diet. In conclusion, this study demonstrates that a low-CHO high-fat low -fiber diet may be deleterious to diabetic rats. In view of insulin sensitivity enhancement , dietary fiber level is irrelevant, as long as the diet has a high-CHO and low-fat level.

• Journal of Powder Materials
• /
• v.12 no.4 s.51
• /
• pp.279-283
• /
• 2005

In this study, the ZnS composite powders for host material in phosphor was synthesized in situ by mechanical alloying. As the mechanical alloying time increases, particle size of ZnS decreases. ZnS powders of $1.85\;\mu{m}$ in a mean size was fabricated by mechanical alloying for 10h. The crystal structures of ZnS powders were investigated by X-ray diffraction and the photo-luminescence properties was evaluated with the optical spectra analyzer. The steady state condition of mechanically alloyed ZnS was obtained as a mean particle size of $2\;\mu{m}$ in 5h milling. The sphalerite and wurtize structures coexist in the ZnS mechanically alloyed for 5h. The ZnS powder mechanically alloyed for 10h grows to the sphalerite structure. And the strong emission peaks of ZnS are observed at 480 nm wave length at the powders of mechanically alloyed for 10h, but the sphalerite and wurtize structures in ZnS coexist and emission peaks are not appeared at the powders of mechanically alloyed for 10h.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.16 no.1
• /
• pp.11-21
• /
• 2020

This study aims to develop and advance the evaluation technology for assessing PHWR safety. For this purpose, the complete loss of AC power or station blackout (SBO) was selected as a target accident scenario and the analysis model to evaluate the plant responses was envisioned into the MARS-KS input model. The model includes the main features of the primary heat transport system with a simplified model for the horizontal fuel channels, the secondary heat transport system including the shell side of steam generators, feedwater and main steam line, and moderator system. A steady state condition was achieved successfully by running the present model to check out the stable convergence of the key parameters. Subsequently, through the SBO transient analyses two cases with and without the coolant leakage via the PHTS pumps were simulated and the behaviors of the major parameters were compared. The sensitivity analysis on the amount of the coolant leakage by varying its flow area was also performed to investigate the effect on the system responses. It is expected that the results of the present study will contribute to upgrading the evaluation technology of the detailed thermal hydraulic analysis on the SBO transient of the operating PHWRs.

• Environmental Engineering Research
• /
• v.19 no.1
• /
• pp.91-99
• /
• 2014

Ordinary heterotrophic organism (OHO) active biomass plays key roles in biological wastewater treatment processes. However, due to the lack of measurement techniques, the OHO active biomass exists hypothetically within the design and simulation of biological wastewater treatment processes. This research was purposed to develop a quick and easy quantifying technique for the OHO active biomass applying a modified batch aerobic growth test. Two nitrification-denitrification activated sludge systems, with 10- and 20-day sludge ages, were operated to provide well-cultured mixed liquor to the batch tests. A steady state design model was firstly applied to quantify the "theoretical" OHO active biomass concentration of the two parent systems. The mixed liquor from the parent systems was then inoculated to a batch growth test and a batch digestion test to estimate the "measured" OHO active biomass concentration in the mixed liquor. The measured OHO active biomass concentrations with the batch growth test and the batch digestion test were compared to the theoretical concentrations of the parent system. The measured concentrations with the batch growth test were generally smaller than the theoretical concentrations. However, the measured concentrations with the batch aerobic digestion tests showed a good correlation to the theoretical concentrations. Thus, a different microbial growth condition (i.e., a higher food/biomass ratio) in the batch growth test, compared to the parent system or the batch digestion test, was found to cause underestimation of the OHO active biomass concentrations.

• Journal of Korean Society for Atmospheric Environment
• /
• v.13 no.2
• /
• pp.161-170
• /
• 1997

The concentrations of dimethylsulfide (DMS) were determined using samples collected from a station located at Kosan, Cheju Island during two field campaigns held in December 1996 and January 1997. The atmospheric DMS concentrations measured at 6-hr intervals during the entire campaign periods, after excluding a few extreme values, spanned in the range of 14 to 410 pptv with mean and 1 SD value of 127 $\pm$ 94 pptv (N=42). Between two month periods during which the field campaigns were conducted, a notable reduction in DMS levels was observed which was comparable to the dramatic shift in air temperature. A considerable difference was also noted in DMS levels, when data were grouped by day/night basis. The cause of unexpected, high day-to-night DMS ratios is best explained in terms of high efficiency of daytime source processes relative to low efficiency of nighttime sink processes due to the characteristics of the study location. The surface water DMS of the study site, although scarcely measured, also behaved similarly to its atmospheric counterpart with its range from 0.3 to 19 nM (N=11). When correlation analysis was conducted between the atmospheric DMS concentration and other concurrently determined parameters, significant correlations were observed from most basic meteorological parameters such as windspeed, relative humidy, and air temperature. However, the existence of "not-so-strong" correlations between air temperature and DMS concentrations relative to other ones indicated that the effect of temperature on DMS behavior must be reflected in more complicated manners at the study site. The sea-to-air flux of DMS was approximated through an application of the mass-balance flux calculation method of Wylie and de Mora (1996) under the assumption that sink mechanism within the marine boundary layer is in steady-state condition with its counterpart, source mechanism. Based on this estimation method, we reached a conclusion that oceanic DMS emitted from the southwest sea of the Korean Peninsula can amount to approximately 9 $\sim$ 36 Gg S $yr^{-1}$.$yr^{-1}$.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.1
• /
• pp.19-24
• /
• 2002

It is a great role that the character of man or woman could be distinguished by hair on the aspect of ornament. Hair will be support of beautifulness of human being in various permanent wave by many kinds of its drugs. Hair is based upon the skin which enroll the body of high living animals and have multiple membrane structure. This study used rat and the effects of commercial permanent wave products to skin which are composed with thioglycolic acid and bases. Results are as follows. Permanent wave penetrated to 4 hours later with steady state in skins and was not significant changeable after 20hr later. In case of neutralizer with thioglycolic acid lag time and permeability coefficient in healthy skin is 3.38hr and $0.094^{\mu}g/cm^{2}$ ${\cdot}$ hr, it old skin is 3.48hr and 0.129$^{\mu}g/cm^{2}$ ${\cdot}$ hr, and it wounded skin is 4.72hr and $0.158^{\mu}g/cm^{2}$ ${\cdot}$ hr. In conclusion, lag time and permeability coefficient in old skin and wounded skin are faster than healthy skin. In vivo which was studied by general time and method of permanent wave. We notified that fine rinkle and rash of skin were changeable in the case of treating with permanent wave drugs than normal skin. We can see even rash and eruption by the naked eye.