• Fire Science and Engineering
• /
• v.32 no.4
• /
• pp.7-16
• /
• 2018

In this study, the prediction performance of design fire curves (DF) was evaluated for gas fires in a compartment by using CFAST. The CFAST simulations adopted the 2-stage DF suggested by the previous study and the Quadratic and Exponential DF suggested by Ingason. It was found by comparing the simulation and experimental results that the overall prediction performance of the design fire cures for the spatially-averaged temperature and concentrations of $O_2$ and $CO_2$ was, from the most reasonable to the most inaccurate, 2-stage DF > Quadratic DF > Exponential DF. The CFAST simulation could not predict for the difference in the spatially-averaged temperature and concentrations of $O_2$ and $CO_2$ at door and inner side locations in a compartment. The CFAST simulations also showed a limitation in the prediction of the spatially-averaged temperature at lower layer and the concentration of CO.

• Fire Science and Engineering
• /
• v.21 no.3
• /
• pp.78-83
• /
• 2007

Diesel, a kind of petroleum, which is used in vehicles, vessels, boilers etc causes great damage when a fire happens, because it has higher caloric value than gasoline or kerosene has at burning. Therefore, pool fire experiment was carried using diesel which is sold on the gas station and radiation heat flux that occurs from flame and inner temperature of flame at burning was estimated. The maximum instantaneous flame temperature of diesel was more than $900^{\circ}C$, and the average of maximum flame temperature was $800^{\circ}C$ which occurred at 0.5 H/D distance from the surface of inflammable liquid, the distance has more long that has the lower the temperature of flame. In case of radiation heat flux, it grew to vary according to the size and amount of sample. When the size of a container for experiment was 0.5 m and sample layer was 13 mm and 20 mm, the radiant heat was 92.29 kW and 117.43 kW each. When the container was 1.0 m, it was 364.35 kW and 405.88 kW each.

• Korean Journal of Materials Research
• /
• v.23 no.5
• /
• pp.293-298
• /
• 2013

In this study, an HP-mod. type(KHR-45A), which is used as a heater tube material in the pyrolysis process, was evaluated for its carburizing properties. It was confirmed from the microstructural observation of the tubes that the volume fraction of carbide increased and that the coarsening of Cr-carbide generated as a degree of carburization increased. The depth of the hardened layer, which is similar to the thickness of the carburized region of each specimen, due to carburization is confirmed by measurement of the micro-Vickers hardness of the cross section tube, which thickness is similar to that of the carburized region of each specimen. Two types of chromium carbides were identified from the EBSD (electron back-scattered diffraction) image and the EDS (energy-dispersive spectroscopy) analysis: Cr-rich $M_{23}C_6$ in the outer region and Cr-rich $M_7C_3$ in the inner region of tubes. The EDS analysis revealed a correlation between the ferromagnetic behavior of the tubes and the chromium depletion in the matrix. The chromium depletion in the austenite matrix is the main cause of the magnetization of the carburized tube. The method used currently for the measurement of the carburization of the tubes is confirmed; carburizing evaluation is useful for magnetic flux density measurement. The volume fraction of the carbide increased as the measuring point moved into the carburized side; this was determined from the calculation of the volume fraction in the cross-section image of the tubes. These results are similar to the trends of carburization measurement when those trends were evaluated by measurement of the magnetic flux density.

• Korean Journal of Veterinary Research
• /
• v.35 no.1
• /
• pp.1-9
• /
• 1995

The development of omasum in fetuses between 60, 90, 120 days of gestation and neonates of Korean native goats was investigated by fight; scanning electron microscopy. The results were summarized as follows : 1. In the 60-day-old fetuses, the stomach was developed and differentiated into four compartments of rumen, reticulum, omasum, and abomasum. The mucosa of the omasum was thrown into folds which appeared to be three or four different orders of large, medium, small, and smallest laminae. 2. In the 90-day-old fetuses, the omasal laminae had increased greatly in length and cores of omasal laminae were invaginated laterally. 3. In the 120-day-old fetuses, the wall of the omasal laminae had increased in length and the lamina epithelialisis had slightly increased in thickness. The lateral invaginations at the dark zone had increased in length and depth. The tunica muscularis increased only slightly in thickness particularly within its inner circular layer. 4. In the neonate, the muscularis and the omasal laminae had increased in thickness. The lateral invaginations of the dark zone were observed in the first, second and third order of omasal laminae. 5. Scanning electron microscopic studies : In the 90-day-old fetuses, numerous microvilli and microridges were observed on the luminar surface of the omasal mucosa. The omasal papillae were already formed at 120 days of gestation. In the I20-day-old fetuses omasal papillae liked nipple shape. In the neonate, the omasal papillae liked the thumb.

• 한국해양학회지
• /
• v.13 no.2
• /
• pp.17-25
• /
• 1978

General water quality parameters were measured, as a base-line study, for possible water pollution problems in the coastal waters of some important harbors and near-sea industrial complexes all around coastal zones of Korea from June 1 to October 15, 1977. The areas surveyed were near Mugho-Samcheog, Ulsan, Jinhae-Masan, Yeosu-Gwangyang, Mogpo, Gunsan and Incheon. Among the surveyed coastal areas, the Ulsan and the Jinhae-Masan areas showed high levels of dissolved oxygen, pH, COD and nutrients. Particularly, the surface waters of the Ulsan inner bay represented COD 15.6mg/l and NO$\sub$2/-N 110$\mu\textrm{g}$/l. The surface layer of the Masan bay displayed pH 8.92 and NO$\sub$3/-N 372$\mu\textrm{g}$/l, while 309$\mu\textrm{g}$/l of PO$\sub$4/-P was recorded in the surface of the Haengam bay. In general it is shown that some coastal areas are presenting signs of pollution from man's activities.

• Journal of the Korean institute of surface engineering
• /
• v.53 no.2
• /
• pp.72-79
• /
• 2020

Two Fe-Cr steels of T22 steel and STS430 steel were corroded at 650 and 750℃ for 100hr in sewage sludge-(0.3% SO₂-6% O₂-10% H₂O-balance CO₂) mixed gas environment. T22 steel corroded faster than STS430, indicating that the Cr content significantly influence the corrosion rates. T22 formed thick and non-protective Fe₂O₃ as the major oxide and Fe₃O₄ as the minor one. With an increase in corrosion temperature, their corrosion rates increased, being accompanied with formation of pores and cracks in the thickened oxide scales that were non-adherent. STS430 steel formed Fe₂O₃, Fe₃O₄ as the outer scale and (Fe, Cr)-O as the inner layer by which its corrosion rate is greatly reduced. Both the T22 and STS430 steel samples formed multi-layered scales by outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions at high-temperature more than 650℃.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2007.04a
• /
• pp.1-4
• /
• 2007

This study investigated the applicability of insulation curing method with double layer bubble sheets to the man concrete subjected to cold weather. Temperature history of the mass concrete indicated that the highest temperature of center section was exhibited at $34^{\circ}C$ while the that of surface section was $25^{\circ}C$. Difference between center and surface was shown to be less $10^{\circ}C$ when the temperature of center section was peak section, and thereby associated temperature cracking index was calculated 1.5, and occurrence probability of temperature cracking was 5%, so there was no temperature cracking caused by internal restraint. No temperature crack was observed by naked eye. It was clear that early frost demage and temperature cracking could be restrained due to reducing temperature difference between inner part and outside in the case double bubble sheets applied to insulation curing method in cold weather. The maturity of mass concrete is higher than outside about $72\sim89^{\circ}$ DD, so it was demonstrated to prevent early frost demage and ensure strength excellently. Insulation curing method with double bubble sheets was more economic than heating curing method.

• The Korean Journal of Malacology
• /
• v.5 no.1
• /
• pp.1-9
• /
• 1989

A scanning electron microscopic study on the glochidium and glchidial encystment of Anodonta grandis on the guppy was conducted. The shape of the glochidium is apparently triangular and its averge size is 0.45mm X0.4mm when closed, The two glochidial shell valves are of the same size, kept together by a ligament of 120${\mu}{\textrm}{m}$ in length and 7 ${\mu}{\textrm}{m}$ in width. Each of the glochidial shell valves has a 16 ${\mu}{\textrm}{m}$ long hook sitdded with many spines on the superior face. A large area to the apex of the valve surrounding the base of the hook is provided with numerous small spines which become progressively smaller towards the periphery of the area, The external surface of the glochidial shell valve is covered with numerous small processes showing successive change in the shape and the pattern of destribution by part. Besides the processes, there are a number of niches scattered all over the exterior surface. The glochidial shell valve has two layers. One is the outer thin membrane bearing the processes and the niches and the others is the inner layer bearing numerous holes which any accessory structure and 2.65 ${\mu}{\textrm}{m}$ in diameter, emerges from a canal located at center of ventral plate of the mamtle, A total of three types of the hair cells are observed. In present artificial infection of the glochidium to the guppy, it took about three to four hours to complete an early cysts, During the period of encystment, The epithelial cells of the host fish actively migrated toward the attached glochidium and covered it.

• Nuclear Engineering and Technology
• /
• v.42 no.5
• /
• pp.576-581
• /
• 2010

KAERI (Korea Atomic Energy Research Institute) fabricated MOX (Mixed Oxide) fuel pellets as a cooperation project with PSI (Paul Scherrer Institut) for an irradiation test in the Halden reactor. The MOX pellets were fitted into fuel rods that included instrumentation for measurement in IFE (Institutt for Energiteknikk). The fuel rods were assembled into the test rig and irradiated in the Halden reactor up to 50 MWd/kgHM. The irradiated fuel rods were transported to the IFE, where ceramography was carried out. The fuel rods were cut transversely at the relatively higher burn-up locations and then the radial cross sections were observed. Micrographs were analyzed using an image analysis program and grain sizes along the radial direction were measured by the linear intercept method. Radial cracks in the irradiated MOX were observed that were generally circumferentially closed at the pellet periphery and open in the hot central region. A circumferential crack was formed along the boundary between the dark central and the outer regions. The inner surface of the cladding was covered with an oxide layer. Pu-rich spots were observed in the outer region of the fuel pellets. The spots were surrounded by many small pores and contained some big pores inside. Metallic fission product precipitates were observed mainly in the central region and in the inside of the Pu spots. The average areal fractions of the metallic precipitates at the radial cross section were 0.41% for rod 6 and 0.32% for rod 3. In the periphery, pore density smaller than 2 ${\mu}m$ was higher than that of the other regions. The grain growth occurred from 10 ${\mu}m$ to 12 ${\mu}m$ in the central region of rod 6 during irradiation.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.40 no.3
• /
• pp.259-268
• /
• 2014

Non-invasive technologies in skin research have enabled to use a live image of living skin without a biopsy or histologic processing of tissue. Confocal scanning laser microscope (CSLM) operated at a near-infrared wavelength of 830 nm allows visualization of inner structure of skin as a non-invasive manner. According to previous researches using CSLM, melanin cap and papillary ring were clearly observed in pigmented areas between stratum basale and papillary dermis. In this study, conversional analysis of CSLM digital images into numerical estimation using scanning probe image processor (SPIP) software was attempted for the first time. It is concluded that a quantification of CSLM images can pave way to expand the field of applications of CSLM.