• International Journal of Automotive Technology
• /
• v.5 no.1
• /
• pp.1-7
• /
• 2004

In line with the Super Ultra Low Emission Vehicle (SULEV) regulation, the main idea in this study has been focused on the utilization of hydrocarbon adsorber (HCA) to adsorb the excess hydrocarbons emitted during a period of engine cold-start, As main recipes of HCA materials, many types of zeolite as well as the combination of alumina and precious metals were used, Representative physico-chemical factors of zeolite such as acidic and hydrophobic properties were characterized. The optimum recipe of HCA materials was also determined. Among the acid properties of zeolites, the Si/Al ratio was found to be the most important factor to get higher hydrocarbon adsorption capacity.

• International Journal of Reliability and Applications
• /
• v.8 no.1
• /
• pp.67-82
• /
• 2007

This paper deals with the effectiveness analysis of an engineering system, which has two units of different strengths in parallel and one unit as a cold standby unit. Failure times for all the units have negative exponential distribution whereas their repair times have general distribution. Single server caters the need for the system. The effectiveness analysis of the system is done by using regenerative point technique. The different measures of effectiveness such as mean sojourn time, mean time to system failure, availability, busy period, etc, are derived. Cost factors also taken into consideration.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.491-494
• /
• 2005

This study was carried out to examine application of surface adiabatic curing method in slightly cold weathering period. So, early aged freezing damage and compressive strength of concrete were examined through temperature analysis of construction concrete. Temperature analysis was carried out according to the average temperature, concrete placement completion time and surface adiabatic curing method. Analysis results show that additional curing plans are demanded in concrete construction below 0$^{circ}C$, surface adiabatic curing method is could apply in the average temperature more than -2$^{circ}C$ and curing method as heating are needed under -2$^{circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.11a
• /
• pp.29-32
• /
• 2006

Experimental test results of field construction, Cheongju University Educational Liberal Art Building, applying the insulating curing method on slab concrete showed that the quality of concrete in fresh and hardened state satisfied all target values. Temperature history of slab concrete in A and B area secured more than $7.8{\sim}9.2^{\circ}C$ higher than outside atmosphere. After completing certain curing period of time on the surface of the structure, crack occurrence was not found. It is concluded that the preventing vaporization of moisture by the insulating curing method reduces plastic and drying shrinkage as welt as improves durability.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.11a
• /
• pp.211-216
• /
• 1999

One of the problems in a refrigerator operation is the frost formation on a cold surface of the evaporator. The frost layer is formed by the sublimation of water vapor when the surface temperature is below the freezing point. This frost layer is usually porous and formed on the cold surface of the evaporator. The frost layer on the surface of a evaporator will make side effect such as thermal resistance. However, these important factors have not been used in determining the defrosting period. In this report, a prediction taking into account the change of the fin efficiency due to the growth of the frost layer.

• Journal of the Korean Institute of Navigation
• /
• v.8 no.1
• /
• pp.49-70
• /
• 1984

Spatial and temporal variations of hydrography and currents are investigated in the Southeastern Sea of Korea during October 1982. The distribution of the water mass of high salinity (>34.40${\textperthousand}$) and low dissolved oxygen concentration (<5.0ml/l) indicates that the Tsushima current flows northward as it passes the Western Channel of the Korea Strait. The cold water (<$6.0^{\circ}c$) with low salinity (<$34.20{\textperthousand}$) and high dissolved oxygen concentration (>6.0ml/l) reaches the bottom of the western channel of the Korea Strait after flowing southward leaning against the slope rather than following the deepest part of the Channel. Repeated sections in the Korea Strait show a remarkable change of hydrographic structure over a period of 4 days ; both warn and cold waters are intensified, particularly in the eastern part of the strait toward the Tsushima Island.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.199-199
• /
• 2017

This study investigated the aspects of damage due to low temperature treatment in order to establish the damage criterion according to low temperature invasion during regeneration period in wheat after regeneration period in the early spring. We cultivated wheat cultivar 'Geumgang' in Wagner pots and treated them with three types of low temperature, and the gradual temperature change program was set in a low temperature incubator for 12.5 h per day for 5 days during the night time when the length of young spikes was about 1 mm. All treatments except for the control were treated in 5 steps for each temperature. Treatment 1 was treated at the lowest temperature $-5^{\circ}C$ for 5 h, treatment 2 for 7 h at $-5^{\circ}C$, and treatment 3 for 9 h at $-5^{\circ}C$. The most common type of damage was partial infertility, and there were some discolored spikes. The damage rate of wheat spikes treated at $-5^{\circ}C$ for 9 h was the highest, while the damage rates of wheat sprouts treated at 5h and 7h were not different from each other. It was found that the damage of wheat spikes exposed to low temperatures for a long time was large. It is necessary to investigate the aspects of spike damage by duration days of low temperature.

• Atmosphere
• /
• v.20 no.3
• /
• pp.261-271
• /
• 2010

Carbon isotopic compositions of the YC-2 stalagmite in Yongcheon Cave were analyzed to delineate paleoclimatic variations near Korean peninsula for the past historical period. The YC-2 stalagmite is about 68 mm long and annual growth laminae are distinctively identified. Because the number of growth laminae is at least 242, the stalagmite can be estimated to be at least 241 years old. At about 15 mm from the bottom, one thick brown growth lamina is observed, and this lamina was likely to have been formed when the stalagmite ceased to grow, making the hiatus. High resolution, carbon isotope data indicate past fluctuations of East Asia monsoonal intensity (intimately related to the amount of precipitation). Based on the carbon isotope trend, the stalagmite can be divided into three stages (Stages I, II and III). The highest carbon isotopic compositions of Stage I (${\delta}^{13}C$=-3.3~0.4‰, PDB) indicate that the stalagmite grew during the Little Ice Age when cold and dry climate prevailed with less vegetation. Stage II is characterized by a transitional period from cold and dry to warm and wet climate with a increasing trend of carbon isotopic compositions (${\delta}^{13}C$=-9.6~-0.6‰) and this period indicates the weakening of the Little Ice Age climate. This decreasing trend also suggests that Little Ice Age was terminated near middle 1870's around Korean peninsula. Relatively low carbon isotopic compositions during Stage III (${\delta}^{13}C$=-11.0~-8.0‰) indicates that the climate was changed to warm and wet conditions which are similar to the present.

• Journal of Information Processing Systems
• /
• v.15 no.6
• /
• pp.1350-1364
• /
• 2019

The ice damage occurs frequently in cold and dry region of western China in winter ice period and spring thaw period. In the drift ice condition, it is easy to form different extrusion force or impact force to damage tunnel lining, causing project failure. The failure project could not arrive the original planning and construction goal, giving rise to the water allocation pressure which influences diversion irrigation and farming production in spring. This study conducts the theoretical study on contact-impact algorithm of drift ices crashing diversion tunnel based on the symmetric penalty function in finite element theory. ANSYS/LS-DYNA is adopted as the platform to establish tunnel model and drift ice model. LS-DYNA SOLVER is used as the solver and LS-PREPOST is used to do post-processing, analyzing the damage degrees of drift ices on tunnel. Constructing physical model in the experiment to verify and reveal the impact damage mechanism of drift ices on diversion tunnel. The software simulation results and the experiment results show that tunnel lining surface will form varying degree deformation and failure when drift ices crash tunnel lining on different velocity, different plan size and different thickness of drift ice. The researches also show that there are damages of drift ice impact force on tunnel lining in the thawing period in cold and dry region. By long time water scouring, the tunnel lining surfaces are broken and falling off which breaks the strength and stability of the structure.

• The Journal of Korean Obstetrics and Gynecology
• /
• v.22 no.1
• /
• pp.231-242
• /
• 2009

Purpose: For the importance of the postpartum period not only for the women delivered of child but also the newborn babies, the multitude of health professionals have emphasized increasingly special care during this period. However, there has been no decisional consensus both in the concepts and the ways of postpartum cares between health professionals and non-professionals. In this study, we explored the ethnical and racial diversities concerning postpartum period focusing on their beliefs and practices. Methods: Literature review was used as main research method for topic of the study. To carry out the method, papers related with postnatal care were searched at the Pubmed, the Korea Education & Research Information Service. Results: 1. Differences between Western and non-Western cultures in terms of postnatal care were found out in the study. 2. The study has proved that non-Western cultures have shared the similar beliefs and practices in postnatal care, although some ethnical and racial diversities specially in duration for care and diets for mother etc. 3. It was found that most prominent similarities among non-Western cultures in postnatal care have centered mainly on the issues such as 'Hot and Cold balance', postnatal confinement etc. Conclusion: Based on the results of the study, it should be suggested that the health professionals do their efforts in understanding deeply the intrinsic diversities on the beliefs and the practices about postnatal care and providing the adequate services and cares reflecting them properly.