• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.59 no.4
• /
• pp.462-466
• /
• 2010

The purpose of this study is to evaluate the safety of a wire connector fabricated for the effective installation of a lighting fixture including its contact resistance, insulation resistance, withstanding voltage characteristics, etc., and to provide the basis for the analysis and judgment of PL(Product Liability) dispute by presenting a damage pattern due to a general flame and overcurrent. This study applied the Korean Standard (KS) for the incombustibility test of the connector using a general flame and performed an overcurrent characteristics test of the connector using PCITS (Primary Current Injection Test System). The contact resistance of the housing connector was measured using a high resistance meter and the insulation resistance was measured using a multimeter. In addition, a supply voltage of AC 1,500V for testing the withstanding voltage characteristics was applied to both ends of the connector. Measurement was performed on 5 specimens and the measured values were used as a basis for judgment. Since the connector is fabricated in the form of a housing, it can be connected and separated easily and has a structure that allows no foreign material to enter. In addition, since it has a structure that allows wires to be connected only when their polarity is identical, any misconnection that may occur during installation can be prevented. When the incombustibility test was performed by applying a general flame to the connector, it showed outstanding incombustibility characteristics and the blade and blade holder connected to the housing remained firmly secured even after the insulation sheath (PVC) was completely destroyed by fire. In addition, the mechanism of the damaged connecting wire showed a comparatively uniform carbonization pattern and it was found that some residual melted insulation material was attached to both ends. In the accelerated life test (ALT) to which approximately 500% of the rated current was applied, the connector damage proceeded in the order of white smoke generation, wire separation, spark occurrence and carbonization. That is, it could be seen that the connector damaged by overcurrent lost its own metallic color with traces of discoloration and carbonization. The contact resistance of the connector at a normal state was 2.164mV/A on average. The contact resistance measured after the high temperature test was 3.258mV/A. In addition, the insulation resistance after the temperature test was completed was greater than $10G\Omega$ and the withstanding voltage test result showed that no insulation breakdown occurred to all specimens showing stable withstanding voltage and insulation resistance characteristics.

• Safety and Health at Work
• /
• v.8 no.4
• /
• pp.386-392
• /
• 2017

Background: Fire service workers often implement multiple duties in the emergency conditions, with such duties being mostly conducted in various ambient temperatures. Methods: The aim of the current study was to assess the firefighters' physiological responses, information processing, and working memory prior to and following simulated firefighting activities in three different hot environments. Seventeen healthy male firefighters performed simulated firefighting tasks in three separate conditions, namely (1) low heat (LH; $29-31^{\circ}C$, 55-60% relative humidity), (2) moderate heat (MH; $32-34^{\circ}C$, 55-60% relative humidity), and (3) severe heat (SH; $35-37^{\circ}C$, 55-60% relative humidity). It took about 45-50 minutes for each firefighter to finish all defined firefighting activities and the paced auditory serial addition test (PASAT). Results: At the end of all the three experimental conditions, heart rate (HR) and tympanic temperature (TT) increased, while PASAT scores as a measure of information processing performance decreased relative to baseline. HR and TT were significantly higher at the end of the experiment in the SH ($159.41{\pm}4.25beats/min$; $38.22{\pm}0.10^{\circ}C$) compared with the MH ($156.59{\pm}3.77beats/min$; $38.20{\pm}0.10^{\circ}C$) and LH ($154.24{\pm}4.67beats/min$; $38.17{\pm}0.10^{\circ}C$) conditions (p < 0.05). There was no significant difference in PASAT scores between LH and MH (p > 0.05). Nonetheless, there was a measurable difference in PASAT scores between LH and SH (p < 0.05). Conclusion: These consequences demonstrate that ambient temperature is effective in raising the physiological responses following firefighting activities. It is therefore argued that further increase of ambient temperature can impact firefighters' information processing and working memory during firefighting activity.

• Journal of Veterinary Clinics
• /
• v.31 no.6
• /
• pp.477-482
• /
• 2014

The aim of this study was to investigate and compare technique, surgical time, and complications of laparoscopic ovariectomy using $LigaSure^{TM}$ and bipolar vessel sealing system in cats. Laparoscopic ovariectomy was performed under general anesthesia on 10 healthy female cats admitted for elective ovariectomy. Surgery was performed through three midline portals. Each ovary was randomly-assigned to removal by use of either $LigaSure^{TM}$ or bipolar vessel sealing system. Duration of predetermined surgery intervals and complications were compared. Bipolar OVE ($2:16{\pm}1:14$ minutes) took significantly longer surgical time compared to the $LigaSure^{TM}$ OVE ($1:24{\pm}0:59$ minutes, P = 0.021). The ovarian pedicle fat and obesity did not influence surgery duration. Intraoperative hemorrhage occurred with bipolar OVE in three cats, but had no significant influence on surgical time. The results suggest that both $LigaSure^{TM}$ and bipolar devices appear to be effective, but $LigaSure^{TM}$ can be used as a stand-alone device that decreases surgical time and complication compared with bipolar vessel sealing system.

• Toxicological Research
• /
• v.14 no.4
• /
• pp.515-523
• /
• 1998

Oxidative stress by reactive oxygen species (ROS) damages cellular DNA, RNA, proteins, lipids and others causing various diseases such as cancer, arthritis, and heart diseases. 8-Hydroxyguanine (8-OHG) is one of the products formed from DNA or RNA damaged by ROS. Since high amounts of 8-OHG can be excreted in urine, it may serve as a potential biomarker indicating the level of oxidative damage to nucleic acids. Residents in industrial area with severe air pollution are expected to be affected by higher level of oxidative stress from pollutants like polyaromatic hydrocarbons (PAHs), etc. Smokers are also expected to be damaged by higher level of oxidative stress from cigarette smoke components like PAHs than non-smokers. To examine if the determination of the urinary concentration of 8-OHG could be used as exposure biomarker for the oxidative stress caused by air-pollutants, this study was performed to determine and compare the urinary concentrations of 8-OHG in smokers and non-smokers, or non-polluted area residents and polluted area residents. Urine samples were collected and purified by a strong cation exchange and cellulose partition column, then analyzed by HPLC with electrochemical detector at 600 ㎷ potential. Concentrations of urinary 8-OHG in non-smokers and smokers of Seoul area college male students were determined as 15.12$\pm$9.68 (ng/mg creatinine) and 34.72$\pm$11.72 (ng/mg creatinine), respectively, showing significantly higher level of 8-OHG in smokers than in non-smokers. Urine samples of elementary school students were collected from Sokcho area, which is known to be non-polluted, and 3 representative polluted areas; Yocheon industrial area, Ulsan urban and Ulsan industrial area. The concentrations of 8-OHG in these samples were 12.42$\pm$8.27 (ng/ mg creatinine, Sokcho), 22.55$\pm$9.12 (ng/mg creatinine, Yocheon), 17.41$\pm$2.30 (ng/mg creatinine, Ulsan urban), 55.04$\pm$39.73 (ng/mg creatinine, Ulsan industrial). Thus, samples from polluted area tend to have higher level of 8-OHG and the levels of Yocheon and Ulsan industrial area were significantly higher than that of Sokcho area. The results indicate that the residents of polluted industrial area or smokers are more severely exposed to oxidative stress probably caused by air pollutants like PAHs. Thus, the determination of urinary 8-OHG concentration could be used as biomarker for the extent of body exposure to oxidative stress caused by various pollutants.

• Fire Science and Engineering
• /
• v.23 no.6
• /
• pp.1-9
• /
• 2009

In this study, the burning behaviours of five different kinds of carpet samples covered with nylon, PP (polypropylene), PTT (poly(trimethylene terephthalate)), wool fabric and NW (nylon and wool) were evaluated by using the cone calorimeter having a radiant flux of 50kW/$m^2$. And the combustion gas toxicity was evaluated according to KS F 2271 test method. As a result of the cone calorimeter test (KS F ISO 5660-1), nylon carpet samples were ignited most easily. In ignition ability or initial flammability, NW carpet samples showed the highest value. In heat release rate (HRR), fire intensity, PP carpet samples were larger than any other samples. Nylon carpet samples were the highest smoke production rate, while N/W carpet samples the lowest. The following were in mass loss rates: NW > wool > nylon > PP > PTT. CO (carbon monoxide) was one of the most toxic gases released from the combustion. PTT carpet samples gave rise to the highest CO concentration, while NW carpet samples the lowest. In addition, PP carpet samples caused the highest $CO_2$ (carbon dioxide) concentration, while NW carpet samples the lowest. Toxicity of the gas produced from carpet samples was determined by the mouse stop motion, and it resulted in the fact that the combustion gas of PTT carpet samples was more toxic than that of any other samples.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.204-212
• /
• 2016

This study was conducted to develop an edible smoked egg by penetrating seasoning through pressurization without damaging the eggshell and to investigate the quality characteristics of the product. The lyophilized smoked egg consisted of 2.43% moisture, 4.11% crude ash, 46.08% crude protein, 40.85% crude fat and 6.53% hydrated carbon. The total content of polyphenol was 3.11 mg%, 35.70% saturated fatty acid and 64.30% unsaturated fatty acid. Major types of saturated fatty acids included palmitic acid (C16:0), stearic acid (C18:0) and lauric acid (C12:0), while major unsaturated fatty acids included oleic acid (C18:1) and linoleic acid (C18:2). Due to smoking of the egg, the eggshell is dark brown, the egg albumen, egg yolk and egg shell are darker than boiled eggs, and the value of a (redness) is higher than that of boiled eggs. Overall, smoked eggs were organically superior than boiled eggs because of their seasoning and smoke flavor. The results of this study are expected to further the development of processed foods using domestic eggs and improve the egg processing industry.

• Journal of the Korean Institute of Gas
• /
• v.2 no.1
• /
• pp.28-39
• /
• 1998

This study investigated the natural convection and radiation in a rectangular enclosure with ceiling vent experimentally and numerically. A heat source is located on the center of the bottom surface. The analysis was peformed a pure convection and is combination of natural convection and radiation. The shape of the considered two dimensional model is a square whose center of ceiling($30\%$) is opened. The numerical simulations are carried out for the pure natural convection case and the combined heat transfer case by using the SIMPLE algorithm. For the turbulent flow, Reynolds stresses are closed by the standard $k-{\epsilon}$ model and the wall function is used to determine the wall boundary conditions. The experiment was performed on the same geometrical shape as the computations. The radiative heat transfer is analized by the S-N discrete ordinates method. The results of pure natural convection are compared with those of combined heat transfer by the velocity vectors, stream lines, isothermal lines. The results obtained are as follows 1. Comparing the results of pure convection with those of the combined convection-radiation through the shape of stream lines, isothermal lines are similar to each other. 2. The temperature fields obtained by numerical method are compared to those obtained by experimental one, and it is found that they are showed mean relative error $8.5\%$. 3. Visualization bt smoke is similar to computational results.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.42 no.2
• /
• pp.119-126
• /
• 2016

Skin is the largest organ that protects the body from the external environmental factors such as smog, cigarette smoke, UV. Protective skin barrier is composed with keratinizational keratinocytes and intercellular lipids such as ceramides, cholesterols and fatty acids combined by the lamellar liquid crystal structure. In this research, we confirmed that the Jeju wild ginseng (JWG) extracts dose-dependently increased the expression of serine-palmitoyltransferase (SPT) protein which is associated with ceramide biosynthesis. In addition, emulsion containing 5% JWG extract was applied on skin of human volunteers for 2 weeks and then significantly reduced transepidermal water loss (TEWL) compared to that of control group. As a results, JWG extract increased the biosynthesis of ceramides that is the key components of the skin lipid through enhancing expression of SPT. In addition, JWG extract reduced TEWL resulting in improvement of skin barrier function. In this context, we suggest that JWG extract could be used as a skin barrier enhancer and moisturing agents in cosmetic fileds.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.3
• /
• pp.83-89
• /
• 2011

A series of full-scale testing was conducted to examine the effect of stairwell pressurization on the pressure differential between the stairwell and the auxiliary room and between the auxiliary room and the residence. Also, flow velocity profiles at open doors were measured. The building tested was a condominium that had twenty floors above the ground and two floors underground. For pressurization of the stairs, a blower was used to supply air into the stairwell at one location underground. Thirteen different cases were tested, and test variables included the number of floors with open doors and the flow rate of the air supply. When the doors on the first floor were open, the pressure differential between the stairwell and the auxiliary room was distributed almost uniformly except for locations near the first floor. When the flow rate was in the range of 180~270 CMM and the doors of one floor were open, the flow velocity could satisfy the requirement of fire safety standards and the stairwell pressure was positive at all levels. However, the minimum pressure requirement (10 Pa) could not always be satisfied. When doors on two floors were open, the flow velocity requirement could be satisfied by increasing the flow rate, but it was found impractical to satisfy the minimum pressure requirement without causing excessive pressure differential in the area near the blower.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.5
• /
• pp.325-337
• /
• 2021

On the road and rail tunnels, the evacuation pathway and facilities such as smoke-control and fire suppression system are essential in tunnel fire. In the long twin tunnels, the cross-connection tunnel is usually designed to evacuate from the tunnel where the fire broke out to the other tunnel. In twin shield tunnels, the segment lining has to be demolished to construct the cross-connection tunnel. Considering the modern shield TBM is mostly the closed chamber type, the exposure of underground soil induced by removal of steel segment lining is the most danger construction step in the shield tunnel construction. This case study introduces the excavation method using the thrust of large steel pipe and reviews the measured data after the construction. The large steel pipe thrust method for the cross-connection tunnel can stabilize the excavated face with the two mechanisms. Firstly, the soil in front of excavated face is cylindrically pre-supported by the large steel pipe. Secondly, the excavated face is supported by the plugging effect caused by the soil pressed into the steel pipe. It was reviewed that the large steel pipe thrust method in the cross-connection tunnel is enough to secure the construct ability and stability in soil from the measurement results about the deformation and stress of steel pipe.