• Corrosion Science and Technology
• /
• v.6 no.5
• /
• pp.233-238
• /
• 2007

Due to the occasional occurrence of a localizedcorrosion such as a SCC and pitting in steam generator tubing(Alloy 600), leading to a significant economical loss, an effective repair technology is needed. For a successful electrodeposition inside a tube, many processes should be developed. Among these processes, an anode to be installed inside a tube, a degreasing condition to remove any dirt and grease, an activation condition for a surface oxide elimination, a strike layer forming condition which needs to be adhered tightly between an electroforming layer and a parent tube and a condition for an electroforming layer should be established. Through a combination of these various process condition parameters, the desired material properties can be acquired. Among these process parameters, various material properties including a mechanical property and its variation along with the height of the electrodeposit inside a tube as well as its thermal stability and SCC resistance should be assessed for an application in a plant. This work deals with the material properties of the Ni electrodeposits formed inside a tube by using the anode developed in this study such as the current efficiency, hardness, tensile property, thermal stability and SCC behavior of the electrodeposit in a 40wt% NaOH solution at $315^{\circ}C$. It was found that a variation of the material properties within the entire length of the electrodeposit was quite acceptable and the Ni electrodeposit showed an excellent SCC resistance.

• Korean Journal of Heritage: History & Science
• /
• v.46 no.3
• /
• pp.212-228
• /
• 2013

Stone cultural heritages are repaired by the use of metal stiffeners. The problem is that this type of repair has been based on the experience of workers without specific guidelines and has caused various problems. This is to suggest the structural reinforcement and behavioral characteristics of metal rods to minimize the secondary damage of materials and have the specimens tested and verified to establish the guidelines on how to insert metal stiffeners. When only epoxy resin is applied to the cut surface, only 70% of the properties of the parent material are regenerated and it is required to structurally reinforce the metal stiffener for the remaining 30%. The metal rod is under the structural behavior after the brittle failure of stone material and the structural behavior does not occur when the metal stiffener is below 0.251%. When it accounts for over 0.5%, it achieves structural reinforcement, but causes secondary damage of parent materials. The appropriate ratio of metal stiffener for the stone material with the strength of $1,500kgf/cm^2$, therefore, should be between 0.283% and 0.377% of the cross section of attached surface to achieve reversible fracture and ductility behavior. In addition, it is more effective to position the stiffeners at close intervals to achieve the peak stress of metal rod against bending load and inserting the stiffener into the upper secions is not structurally supportive, but would rather cause damage of the parent material. Thus, most stiffeners should be inserted into the lower part and some into the central part to work as a stable tensile material under the load stress. The dispersion effect of metal rods was influenced by the area of reinforcing rods and unrelated to their diameter. However, it ensures stability under the load stress to increase the number of stiffeners considering the cross section adhered when working on large-scale structures. The development length is engineered based upon the diameter of stiffener using the following formula: $l_d=\frac{a_tf_y}{u{\Sigma}_0}$. Also, helically-threaded reinforcing rods should be used to perform the behaviors as a structural material.

• Korean Journal of Computational Design and Engineering
• /
• v.11 no.2
• /
• pp.115-127
• /
• 2006

At the initial design stage, the generation process of the production material information of a building block and the simulation process of the block erection, which are required to perform the production planning and scheduling, have been manually performed by using 2D drawings, data of parent ships, and design experiences. To make these processes automatic, the accurate generation method of the production material information and the convenient simulation method of the block erection using the 3D CAD model, which was generated from the initial hull structural design system early developed by us, were proposed in this study. For this, a 3D CAD model for a whole hull structure was generated first, and the block division method for dividing the 3D CAD model into several building blocks was proposed. The generation method of the production material information for calculating the weight, center of gravity, painting area, joint length, etc. of a building block was proposed as well. Moreover, the simulation method of the block erection was proposed. Finally, to evaluate the efficiency of the proposed methods for the generation of the production material information and the simulation of the block erection, these methods were applied to corresponding processes of a deadweight 300,000 ton VLCC (Very Large Crude oil Carrier). As a result, it was shown that the production material information of a building block can be accurately generated and the block erection can be conveniently simulated in the initial design stage.

• Korean Journal of Rural Living Science
• /
• v.7 no.1
• /
• pp.69-80
• /
• 1996

The purpose of this study is to offer basic data of education to improve farm lives though investigating rural homemakers' life style. The results of this study are as follows : 1. The life structure of rural homemakers was classified into two structures as a material resources and human resources. The life style of rural homemakers was classified into systematical life style, traditional value style, social active style, and progressive active style. 2. The life styles of rural homemakers according to social population variance were as follows. The lower of age, homemakers whose family incomes more 30 million won or below 10 million won, who has religions, who employed in livestock were showed at very systematical life style. The homemakers who live in mountain village, higher the much age becomes, and the education level become lower, have showed traditional value style. Rural homemakers the lower of age, the higher incomes, composed of single parent ＋ children who remain single were appeared social active style. Rural homemakers the lower of age, the more shortened farm life periods, who employed in livestock were appeared progressive active style. 3. Systematical life style was more affected by material resources structure, traditional value style was affected by material resources. And social active style was more affected by human resources, progressive active style was affected by human resources.

• Korean Journal of Childcare and Education
• /
• v.10 no.2
• /
• pp.73-91
• /
• 2014

The purpose of this study was to examine the influence of the happiness of parent users of employer-supported childcare centers on their parental stress and employer-Supported childcare centers satisfaction level. It's basically meant to provide some information on how to ensure work-family reconciliation and improve the performance of employer-supported childcare centers. The subjects in this study were 206 parents who were users of employer-supported childcare centers. The findings of the study were as follows: First, the happiness and childcare centers satisfaction of the parent users of the employer-supported childcare centers were both at a higher level, and their parental stress was slightly above average. Second, there was a negative correlation between the happiness and parental stress of the parents who used the employer-supported childcare centers, and happiness was positively correlated to childcare centers satisfaction level. Third, as for the impact of the happiness of the parent users of the employer-supported childcare centers, parental stress was under the largest influence of happiness, followed by family harmony. happiness had the greatest impact on childcare centers satisfaction level, followed by interpersonal relationships. This outcome suggests that the supportive direction for parenting needs to focus on the affective dimension of promoting parents' happiness as well as focusing on the material and structural dimension.

• Korean Parent-Child Health Journal
• /
• v.6 no.1
• /
• pp.1-17
• /
• 2003

Thus, I studied Health services supplied by local health centers and the requirements of the inhabitants visiting the health care facilities. The purpose of this study was to provide basic material for the establishment of Health care policy and the development of health care businesses. The target places for this study were 4 health centers; Chungrang-Gu, Nowon-Gu, Eunpyung-Gu, Songpa-Gu, with 509 mothers who were visiting the Centers. The question items of this study concerned a total of 124 health-related services provided by the Health Centers. The data was collected for a total of 92 days; July 1st~September 30th, 1999. 800 questionaries were distributed and 559 answered, 509 were analyzed finally. The collected data were processed using the SAS program to get mean, standard deviation, percentage. Open questions were made to reveal the opinions of mothers using the health care center. The results were as follows : 1. Among the participants of the study, 49.7% were 25~29 years of age, 84.3% were house wives by current occupation, 56.2% were from 4~6 person households. 52.1 were educated at a high school level, and 43.6% were educated at a collage level. 2. The highest percentage(53.6%) of the users were spontaneous in their utilization of health care center. The major reason for using the Health care center is that it is free to 65.8% of those covered and of low cost to 19.3% of those covered. 3. The satisfaction level of those using the health care center appeared to be generally high. The general average value showed up as $3.027{\pm}0.519$. 4. The level of recognition of the value of the heath care center services was high, particularly in the basic item of diagnoses of pregnancy, particularly in the basic item of diagnoses of pregnancy. However, the satisfaction level of health care education In pregnancy is low at 20~40%. In the meantime, the level of recognition in breast- feeding benefits is high at 76.8%. 5. The rate of realizing health care center's service campaign was generally low at 10~20%. 41.3 of the people knew the advertizing material of the health care centers. 32.4% of the people knew the advertizing material of the health care centers. 32.4% of the people knew the campaign of health care center for importance of breast-feeding benefits. 30.1% of the people knew the campaign for testing congenital mechanism disease. In the meantime about 50% was recognised the health care centers campaign for the importance and time of infants vaccination. 6. The need for enhancement of health care center services was shown to be high as $3.266{\pm}0.676$ as an average, chicken pox vaccination being the most highly requested at $3.565{\pm}0.587.$. 7. Among the open questions, the additional service to be provided were as follows ; increase of campaign of health care center services, furnishing advertizing books in public locations, providing shuttle bus service to the health care centers, extension of desire for preventative injections, rest and play areas for the children of the families serviced, consultation rooms, etc.

• Journal of Welding and Joining
• /
• v.11 no.3
• /
• pp.48-60
• /
• 1993

The cause of corrosion failure found in structures or various components operating in severe corrosive environments has been attributed to stress corrosion cracking(SCC)which is resulting from the combined effects of corrosive environments and static tensile stress. Slow strain rate test (SSRT) provides a rapid reliable method to determine SCC susceptibility of metals and alloys for a broad range of application. The chief advantage of SSRT procedures is that it is much more aggressive in producing SCC than conventional constant strain or constant load tests, so that the testing time is considerably reduced. Therefore, in this paper, the combined effects of material properties and strain rate on the tensile ductility and fracture morphology of parents and weldment for SM45C, SCM440 and SM20C steels were examined and discussed in synthetic sea water. The susceptibility of SCC was the most severe under the strain rate of $1.0{\times}10^{-6} sec^{-1}$, and R.O.A. can be used for parent and maximum load for weldment to evaluate the parameter for SCC susceptibility.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.2
• /
• pp.39.2-40
• /
• 2016

The molecular gas surrounding an H II region is thought to be a place where star formation can be induced. Such triggered star formation can arise form the overpressurization of existing density enhancements or thought the collapse of a swept up layers of material. In this talk, We will discuss the results of a study of star-formation activity associated with the outer Galaxy ring-shaped H II regions KR 7, KR 81, KR 120 and KR 140 using archival Spitzer and WISE data along with the JHK observations. We used CO data cubes from the FCRAO and TRAO in order to define extent of the molecular cloud associated each HII region. Using the infrared data sets, We identified and classified YSO populations within each molecular cloud using measures such as the class I/II ratio and YSO spatial density. Along with this, one of the main question in the study of star formation is how protostar accrete material from their parent molecular clouds and observations of infall motions are needed to provide direct evidence for accretion. Combining our observation of the YSO population distribution with time scales associated with YSO evolution and HII expansion, we investigated the possible significance of triggered star formation in the molecular cloud surrounding each region.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.1025-1028
• /
• 2009

Earth and rock fill dam is our typical dam because of their inherent flexibility and adaptability to various fundation conditions. In order to secure structural safety, rockfill materials are used angular particles obtained by blasting parent rock or rounded particles collected from river beds. Concrete-faces rockfill dams(CFRD) and Concrete-faces gravelfill dams(CFGD) have become popular in the last 20 years as s result of their good performance and low cost compared with the rockfill dam. These Dams are also constructed by the materials. A key factor in the design of the dams is the deformations induced during construction and upon reservoir filling. These can be predicted using the stress-strain and strength properties can be adequately define. However the stress-strain properties of rockfill are difficult to determine because the properties are affected by such factors as particle grading, size and shape of particles, stress conditions, and particle crushing. In our study, testing of the behavior of the rockfill materials are essential prerequisites to the realistic analysis and design of the CFGD. This paper deals with laboratory testing of particle crushing among the study.

• Korean Chemical Engineering Research
• /
• v.57 no.3
• /
• pp.387-391
• /
• 2019

A highly porous Ni@MIL-101catalyst for urea oxidation was synthesized by anchoring Ni into a Cr-based metal-organic framework, MIL-101, particles. The morphology, structure, and composition of as synthesized Ni@MIL-101 catalysts were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electro-catalytic activity of the Ni@MIL-101catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the structure of Ni@MIL-101 retained that of the parent MIL-101, featuring a high BET surface area of $916m^2g^{-1}$, and thus excellent electro-catalytic activity for urea oxidation. A $urea/H_2O_2$ fuel cell with Ni@MIL-101 as anode material exhibited an excellent performance with maximum power density of $8.7mWcm^{-2}$ with an open circuit voltage of 0.7 V. Thus, this work shows that the highly porous three-dimensional Ni@MIL-101 catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.