• 한국표면공학회지
• /
• 제40권6호
• /
• pp.271-278
• /
• 2007

In this study, applicable possibility in chemical decontamination for reactor coolant pump(RCP) was investigated for the various stainless steels. The stainless steel(STS) 304 showed the best electrochemical properties for corrosion current density and the lowest weight loss ratio in chemical decontamination process model 3-3 than other materials. The weightloss quantity in chemical decontamination process model 3-3 presents the lowest value compare to the other chemical decontamination process model 1, 2, 3-1 and 3-2. In the case of SEM observation, the pitting corrosion was generated in both STS 415 and STS 431 with the increasing numbers of cycle. The intergranular corrosion in STS 431 was sporadically observed. The sizes of their pitting corrosion were also increased with increasing cycle numbers.

• 아동학회지
• /
• 제19권1호
• /
• pp.43-53
• /
• 1998

This study investigated the relations among maternal cognition, maternal supervisory/monitoring behaviors, and their children's peer competence. The participants were 40 kindergarten children and their mothers. The mothers completed a questionnaire concerning maternal beliefs about children's social skills. Also their supervisory/monitoring behaviors were observed in the context of child-peer interactions. Children's peer competence was measured using a sociometric status measure and a peer acceptance rating scale. Maternal beliefs were related both to the quantity/quality of maternal supervisory/monitoring behaviors and to children's peer competence. Maternal supervisory/monitoring behaviors were also related to children's actual peer competence.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 가을 학술발표회 논문집
• /
• pp.529-536
• /
• 2002

The purpose of this paper os to present and discuss some of flow and drain observed in modelling results. Because dredged fill ground of Yul-Chon located in the south coast of Korea is very soft, this ground should be improved after operation of surface stabilization. There are surface stabilization method such as chemical stabilization, desiccation, horizontally vacuum drain, replacement, and geosynthetics. In Yul-Chon, PTM(Progressive Trenching Method) is adopted to provide the necessity condition of surface desiccation. In the case trench in the dredged soft ground is formed by PTM equipment, pore water in the ground is drained through trench. There, drain and desiccation of surface ground increase, and bearing capacity is improved. In this research, when trench in the dredged soft ground is formed by PTM equipment, permeable characteristics and drain efficiency of pore-water are analyzed using SEEP/W software package. Results show variation of total head, pressure head, flux, hydraulic gradient, and flow quantity.

• Journal of Magnetics
• /
• 제16권3호
• /
• pp.216-219
• /
• 2011

Mn doped ZnO films were prepared on Si (100) substrates using sol-gel method. The prepared films were annealed at $550^{\circ}C$ for decomposition and oxidation of the precursors. XRD analysis revealed the presence of ZnMnO hexagonal wurtzite phase along with the presence of small quantity of $ZnMn_2O_3$ secondary phase and poor crystalline nature. The 2D, 3D views of magnetic domains and domain profiles were obtained using magnetic force microscopy at room temperature. Rectangular shaped domains with an average size of 4.16 nm were observed. Magnetic moment measurement as a function of magnetic field was measured using superconducting quantum interference device (SQUID) magnetometry at room temperature. The result showed the ferromagnetic hysteresis loop with a curie temperature higher than 300 K.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2002년도 춘계학술대회 논문집
• /
• pp.549-554
• /
• 2002

Recently, interest in hygiene has been arouse in the health care field. Consequently, Filters with antibacterial agent applied to improve air quality by sterilizing bacteria, fungi, etc. We actually installed antibacterial air filter containing 2.5wt%Ag zeolite on the air intake route to air-conditioner in passenger cu, and evaluated filter's performance on antibacterial effect. By the microbe liquid spattering method, we found that the antibacterial air filter has notably sufficient antibacterial efficiency against standard strains and wild type strains. Antibacterial effect was observed at whole area of filter media by zone of inhibition test. The evaluation of microbe quantity was conducted through mixing dilution plate culture method. In comparison with ordinary filter, the amount of germs attached on antibacterial air filters was larger. The amount of germs attached on ordinary filters was very small since ordinary filters contained less dust. In comparison in antibacterial air filter with thickness, the amount of germs attached on 9mm filter was smaller than that of on 6mm filter. i.e. thicker filter, superior efficiency.

• 한국동물학회지
• /
• 제36권4호
• /
• pp.588-595
• /
• 1993

We have collected a great Quantity of leeches, comprising five species, from six different ponds and rice paddies in the south-western part of Korea. The leeches were cultured in our laboratory with special interests on the blood-suckers (Himdo nipponial in fresh water supplemented with essential ions. A number of experiments was carried out with biomedical aspects. We have observed traits which can be used as a laboratory animal. The paper reports general features obsenred from leeches with preliminary study results carried in culture systems. The paper also describes study aspects of leeches in biochemistry, neurology and developmental biology.

• 물과 미래
• /
• 제11권1호
• /
• pp.47-58
• /
• 1978

This study is concerned with the analysis of the formulas which give both the quantity of the total, suspended and bed loads as functions of stream and sediment characteristics. The numerical analysis of sediment discharge formulas is described and the computer program for the following 4 formulas are developed; (1) Einstein's Formula (2) Toffaleti's Formula (3) Brown's Formula (4) Kikkawa's Formula In the analysis of these formulas, the hydraulic data of the river in the downstream of the Han River are used, and these formulas have been tested by application and comparison with observed data and the results computed by the computer. In these methods and procedures, the most satisfactory and convenient formula is selected. The design and planning of the river channel regulation works are determined by computing the river bed variation by using the sediment discharge computed from the selected formula.

• 한국정밀공학회지
• /
• 제17권1호
• /
• pp.61-67
• /
• 2000

Gears are the most commonly used parts in automotive and industrial applications. One of most common modes of gear failures is tooth breakage, which is usually produced by the bending fatigue failure. It is important to manufacture the gears which can withstand the applied stresses in view of safety and economic requirement. This paper deals with bending fatigue strength for cold forged bevel gear. Especially, to compare fatigue characteristics for manufacturing processes difference, bending fatigue tests of bevel gears made by three different processes respectively. Results indicate that the fatigue strength of bevel gear is improved by cold forging process. Intergranular fracture is found on fatigue fracture surface, and dimples are observed on final fracture surface. The fatigue failure cannot be considered as a deterministic quantity, but must be characterized statistically. This study proposes a method to estimate bending fatigue lift of the bevel gear using the probability-load-life and Weibull analysis.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2006년도 춘계학술대회
• /
• pp.438-441
• /
• 2006

The groundwater level was originally above the surface at the Onyang spa area. However, it is now 98-138m depth below the surface deu to the artificial pumping from boreholes. The fluctuations of the piezometric head were observed in 4 boreholes. Transmissivity estimated from the pumping rate and the drawdown is about $577.51 m^2/day$ The transmissivity of Onyang spa area is much larger than common values of fractured aqui for the drawdown of the piezometric head by artificial pumping is widely spreaded out in that area. The drawdown related to each pumping rate was analyzed and the formula between drawdown and pumping rate was made by a regression analysis. The formula can be applied for the condition of enough groundwater flowing into the Onyang spa area

• Computers and Concrete
• /
• 제33권4호
• /
• pp.409-423
• /
• 2024

Using an extensive database, a sensitivity analysis across fifteen machine learning (ML) classifiers was conducted to evaluate the impact of various data manipulation techniques, evaluation metrics, and explainability tools. The results of this sensitivity analysis reveal that the examined models can achieve an accuracy ranging from 72-93% in predicting the fire-induced spalling of concrete and denote the light gradient boosting machine, extreme gradient boosting, and random forest algorithms as the best-performing models. Among such models, the six key factors influencing spalling were maximum exposure temperature, heating rate, compressive strength of concrete, moisture content, silica fume content, and the quantity of polypropylene fiber. Our analysis also documents some conflicting results observed with the deep learning model. As such, this study highlights the necessity of selecting suitable models and carefully evaluating the presence of possible outcome biases.