• Journal of the Korean institute of surface engineering
• /
• v.28 no.4
• /
• pp.207-218
• /
• 1995

Tungsten(W) metal has excellent properties in heat-resistance, corrison-resistance and impact-resistance but W-Metal is hard to sinter because higher than $2,000^{\circ}C$ is required to sinter W-powder. Con-sequently, a deposit technique of Nikel Phosphorus(NiP) on W-powber by the liquid reduction precipitation method was performed. Sintering temperature of the resulting W-NiP composite was lowered around to $1,000^{\circ}C$, and the mechanical properties of the sintered body was studied. The most suitable conditions for NiP thin film deposit on W-Powder by the liquid reduction precipitation method, which are composition, concentration, pH and temperature of the liquid reduction solution, were considered. The activated sintering was carried out in a reducing condition furnace. Components and properties of the sintered body were investigated by the density and the hardness measurements, X- ray diffraction analysis, and microscopic photographs of the surface. Quantity of NiP thin film on W-powder could be varied by the change of the liquid reduction solution composition. The sintering temperature of W-NiP composite powder is lowered to $950^{\circ}C$ from $2,000^{\circ}C$ and the hardness is increased (ca. 720 Hv). Large shrinkage could be observed since density was increased from 5.5 to 11.0 g/$cm^2$ which 86.2% of theoretical density. W metal and $Ni_3P$ crystal were detected through X-ray diffraction on the sintered body. Perfectly activated sintering was observed by microscopic photographs.

• Journal of the Korean Solar Energy Society
• /
• v.28 no.5
• /
• pp.14-20
• /
• 2008

As the number of buildings that use the transparent permeation materials as the outer wall is on the increase, the coming amount of the light rays is a lot, and thus the increase in the cooling load and the radiant heat of high temperature may cause the residents to discomfort. In order to reduce such influences, this paper analyzed the installation effects of the sunshade BIPV. The inner temperature of the room installed the sunshade BIPV or otherwise was measured, and compared and analyzed the effects of reducing the cooling load by the incoming light rays. The sample space of the third floor of S university installed the sunshade BIPV has two rooms on the same conditions, and for five sunny days selected in August, the researcher measured the air temperature and the temperature of the fittings with closing the windows to minimize the movement of air without operating the coolers. The maximum cooling load measured by the incoming light rays in the room where the sunshade BIPV was not installed was examined as 459.13kcal/h. It can be understood as the effect of reducing the cooling load according to the incoming rays of the room with sunshade BIPV. Even though the effect of cooling load reduction is not so great in a room, the total reduction in cooling room for the 32 rooms installed the sunshade BIPV was estimated to be 40442.27kcal/day, which will be able to bring the maximum reduction effect of 17.1kW in energy and reduce the investment cost owing to the reduction in cooling load when initially designing the building.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.113-114
• /
• 2014

Though polymer cement mortar is widely used to repair or reinforce concrete as it has superior adhesion, dense internal structure, chemical resistance, and workability in comparison to those of general cement mortar, studies on its behaviors in high temperature environment such as fire is urgently required. Accordingly, in this experiment, the degrees of reduction in the compressive strength at different temperatures was grasped applying ISO834 Heating Curve, and the effect of polymer content and type on compressive strength could be determined. As a result of this experiment, it is found that polymer type and content have a big effect on reduction of compressive strength in high temperature range, and not only the dynamic characteristics but also the combustion characteristics in high temperature range are required to be studied considering occurrence of a fire in the future.

• Journal of Korean Academy of Nursing
• /
• v.2 no.1
• /
• pp.237-246
• /
• 1971

The purpose of this study is to observe the effects of ice-pack application on different body areas and to note which body area produces the best results according to age, room temperature, sex and disease. Seventeen patients, including six men and eleven women, hospitalized at Seoul National University Hospital from May 22 to August 29, 1971, ranging in age from 15 through 60 years with an oral temperature of 38℃ or over, were chosen for this study. They were observed with regard to the effect of the ice-packs after applications for 30, 45 or 60 minutes. Four ice-packs, 7.6inch by 9 inch, were applied on the chest and the abdominal surface in the control group and the same size and number of packs on the axillae and political regions in the experimental group. The study results were reviewed in a statistical method to obtain the following findings 1. There was no significant difference in the change of the body temperature between the control group and the experimental group after applying the packs for 30, 45 or 60 minutes. 2. Individually, there was a significant difference in the change of body temperature between before and after application for 30, 45 or 60 minutes. 3. The difference of room temperature also had no merle influence on the body temperature taken immediately before applying the ice-packs. Even when ice-packs were applied for 30, 45 or 60 minutes, the room temperature did not influence the reduction of temperature in the patient. 4. There was a significant difference in the change of the body temperature, according to the sex, after application for 30, 45 or 60 minutes. Male patient's body temperature decreased far more noticeably than the female patients and the degree of reduction became more pronounced the longer the packs were applied. 5. In regard to age, in adults, the degree of reduction in the body temperature by the application of ice-packs was similar after appling them for 30, 45 or 60 minutes and did not depend upon the length of application. 6. Regardless of the disease, there was no great difference in the reduction of body temperature when the ice-packs were applied for 30 or 45 minutes, except for patients with typhoid fever when a striking decrease in the fever resulted after a 60 minute application of the ice-pack.

• The Journal of Engineering Geology
• /
• v.3 no.2
• /
• pp.191-201
• /
• 1993

Reduction is one of the important mechanisrns in decreasing the amount of Cr(VI) in wastewater and this reaction is quite dependent on pH and temperature. Either soil organic materials, or a high inorganic salt concentration with elevated temperature and low pH will provide a good condition for the reduction of Cr(VI) to Cr(III) in deep well injection zones. Chromate reduction by soil organic materials and chloride ion in various environment conditions is investigated. Aquifer and aquitard formation samples have been obtained from a deep well in St. Bernard Parish, and St. Charles Parish, LA, U.S.A., respectively. For this study, pH ranging from -0.81 to 2.0, temperature $50^{\circ}C{\;}and{\;}70^{\circ}C$, and cliloride concentration 0 M, 0.26 M and 0.52 M are used to represent the actual conditions in deep well injection zones.

• Environmental Engineering Research
• /
• v.10 no.5
• /
• pp.239-246
• /
• 2005

The effect of Pt addition over $V_2O_5-WO_3/TiO_2$ catalyst supported on PRO-66 was investigated for NO reduction in order to develop the catalytic filter working at low temperature. Catalytic filters, $Pt-V_2O_5-WO_3/TiO_2/PRD$, were prepared by co-impregnation of Pt, V, and W precursors on $TiO_2$-coated ceramic filter named PRD (PRD-66). Titania was coated onto the pore surface of the ceramic filter using a vacuum aided-dip coating method. The Pt-loaded catalytic filter shifted the optimum working temperature from $260-320^{\circ}C$(for the catalytic filter without Pt addition) to $190-240^{\circ}C$, reducing 700 ppm NO to achieve the $N_x$ slip concentration($N_x\;=\;NO+N_2O+NO_2+NH_3$) less than 20 ppm at the face velocity of 2 cm/s. $Pt-V_2O_5-WO_3/TiO_2$ supported on PRD showed the similar catalytic activity for NO reduction with that supported on SiC filter as reported in a previous study, which implies the ceramic filter itself has no considerable interaction for the catalytic activity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.6
• /
• pp.398-403
• /
• 2010

The drag reduction(DR) of non-ionic surfactant and polymer according to the variation of fluid velocity, temperature and surfactant concentration was investigated experimentally. For this experiment, the kind of surfactant was non ionic amine-oxide and the kinds of polymer were polyacrylamide and xantan gum. An experimental apparatus equipped with one water storage tanks was built and two flow meters, two pressure gauges for data logging system was installed. Results showed that the kinds of polymer, polyacrylamide and xantan gum, had DR of below 20% for below 500 ppm in fluid temperature of $50{\sim}80^{\circ}C$. But the kind of surfactant, amine oxide, had DR of above 40% for 500~1000 ppm in fluid temperature of $50{\sim}80^{\circ}C$. As a result, amin oxide showed better materials to use to the district heating system.

• Journal of the Korean Ceramic Society
• /
• v.51 no.1
• /
• pp.25-31
• /
• 2014

New green phosphor is synthesized by reducing $LiAlO_2:xEu^{3+}$ phosphors in a low pressure $H_2$ atmosphere. The $LiAlO_2:xEu^{3+}$ prepared by a solid state reaction method is reported as red phosphor. The effect of the reduction treatment on the $LiAlO_2:xEu^{3+}$ on the crystalline phase change and photoluminescence (PL) property are characterized. The reduced phosphor had a broad green light spectrum centered at 524 nm. The PL intensity of the reduced phosphor increased to a maximum at the reduction temperature of $1100^{\circ}C$. The PL intensity decreased with a further increase in the reduction temperature. The crystalline phase constituting the reduced phosphor varied with the temperature. A new crystalline phase $Li_2Al_4O_7$ was observed at $1100^{\circ}C$. The origin of the green-light emission is discussed in relation to the crystalline phase change.

• Environmental Engineering Research
• /
• v.24 no.4
• /
• pp.529-542
• /
• 2019

Nowadays, drying methods for municipal solid waste quality improvement have been adopted in the developed and developing countries to valorize wastes for a renewable energy source, reduce dependency on fossil fuel and keep safer disposal at landfills. Among them, biodrying, biostabilization, thermal drying and solar drying are the most common. Drying of municipal solid waste could offer several environmental and economic benefits. Therefore, this review highlighted the drying methods for municipal solid waste quality improvement around the world and compared them based on the reduction of moisture, weight and volume of municipal solid wastes against drying temperature and time by using statistical analysis. It was observed that the drying temperature of different drying methods accounted for 115 ± 40℃ for thermal drying, 59 ± 37℃ for solar drying, 55 ± 15℃ for biodrying and 58 ± 11℃ for biostabilization. Among the drying methods, thermal drying provided the shortest drying time. The moisture reduction, weight reduction, volume reduction and heating value increase of municipal solid waste could vary with drying temperature and time. Finally, the benefits and drawbacks of different drying methods were specified, and recommendations were made for the future efficient drying.

• Korean Journal of Materials Research
• /
• v.20 no.1
• /
• pp.42-46
• /
• 2010

Phosphorus exhibits considerable segregation in steelmaking slag. In order to recover phosphorus from slag to $K_3PO_4$ via molten iron, a carbothermic reaction using microwave heating was suggested recently. The carbothermic reduction of phosphorus from slag to molten iron using microwave heating was carried out at 2073K. However, at this temperature the thermodynamic properties of both slag and molten iron cannot be determined experimentally. Therefore, the computational approach of the so-called CALPHAD method is very useful to understand the transfer of phosphorus from slag to metal and to enhance this reaction. In the present investigation, a theoretical study of the reduction behavior of phosphorus in slag was carried out at much lower temperatures using the recently developed thermodynamic database in the FactSage program. The calculated results showed reasonable accordance with the experimental data; namely, the thermodynamic database could be applied successfully to higher temperature reactions. The current study found that higher temperature and high $SiO_2$ concentration are favorable for the recovery of phosphorus from slag.