• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.22 no.4
• /
• pp.241-247
• /
• 2010

Corrosion of steel embedded in concrete is one of the foremost factors that affect the durability of concrete structures in marine environments. This paper presents an application technique of anode-ladder-system to evaluate corrosion behaviours of marine concrete structure. In order to investigate the behaviours quantitatively, the measurement of potential and current was performed on the concrete elements subjected to the penetration and diffusion of chloride ions. The main variable was the heights from seawater level; namely 3.7, 6.0 and 8.2 m. As a result of the monitoring, it was found that the corrosion characteristics differently behaved with the increasing height. Additionally, through migration test, the relationship between compressive strength of concrete and diffusivity of chloride ions was observed. It is suggested, ultimately, that in order to reduce or mitigate steel corrosion, both appropriate concrete cover depth and high-quality of concrete in early ages should be done.

• Economic and Environmental Geology
• /
• v.2 no.1
• /
• pp.13-33
• /
• 1969

The Mulkum mine, located in Mulkum-myon, Yangsan-Kun, Kyeongsang Province, is one of the biggest iron mine in Korea. The geology of this mine and its vicinity consists of Chusan andesitic rocks and Datae-dong andesite porphyry of the Kyeongsang System which were intruded by biotite granite widely distributed near the vicinity of Mulkum-ni. The ore deposits, embedded in Dotae-dong andesite porphyry, are fissure-filling vein type in origin. Up to present ore bodies of Main vein, No. 2 vein, Eastern No. 1, 2 vein and Western No. 1 vein are exploited. Generally the veins strike N 10-25 E and dip to 60-90 SE. The proved length of vein is more than 500 meters and its depth 150 meters in Main vein with 3-4 meters of thickness in average. Ore minerals are mainly magnetite and locally associated with small amounts of hematite, sphecularite and chalcopyrite. Gangue minerals are quartz, epidote, chlorite, pyroxene, and garnet, etc. The modes of occurrence of vein are as follow; 1. Branching and parallel vein patterns are observed around main shaft in -1 level. 2. Multiple cymoid loops and subrectangular vein patterns are observed around main shaft in -2 level. 2. Single vein patterns are observed in -3 and -5 level. The ore-shoots plunge northeasterly about 20-30 degrees. In conclusion, the tectonically fractured zone belongs to the poorly mineralized zone and shoots are formed as single vein type. The general trends of one-shoots must be applied the prospecting of the deep-seated ore body in the deposits.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.10 no.1
• /
• pp.47-56
• /
• 2003

Purpose: This study was done to provide information about issues of clinical competency from the perspective of new graduate nurses and to make suggestions for improving undergraduate education programmes. It was also done to clarify learning experiences between fundamentals of nursing and the other major areas of nursing. Method: For this study, 7 new graduates and 8 experienced nurses participated. The data were collected through in-depth interviews and analysed in terms of Strauss and Corbin's grounded theory methodology. Result: Core category and main categories, were delineated. Clinical nursing competency was found to be a dynamic process with each participant actively engaged in acquiring problem solving ability in diverse clinical settings. These findings have value in understanding the embedded meaning of clinical nursing competency. Conclusion: Therefore, the educational programs reflecting the experience of new nursing staff should be developed.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.741-746
• /
• 2008

Many methods have been introduced to protect the corrosion of embedded steel in RC structure. One of the methods that restrain corrosion of steel is corrosion inhibitor. The technology that delayed the progress of corrosion is developed recently by converting active rust to passive rust. However, the performance for concrete structure is not fully examined because this corrosion inhibitor is developed for normal metal product. In this study, the application of corrosion inhibitor that use tannin acid is investigated by concrete specimen. According to the results, tannin acid corrosion inhibitor does not occur reduction of workability and strength in concrete. When corrosion inhibitor is added more than 4% per cement weight, the penetration depth of chloride decrease about 10%. Also, corrosion resistance of concrete is improved because tannin acid corrosion inhibitor has an effect on converting the rust of steel into stable state. It is showed in special that the addition more than 6% is effective in corrosion resistance.

• Journal of Ocean Engineering and Technology
• /
• v.31 no.1
• /
• pp.47-59
• /
• 2017

This study conducted numerical simulations using LES-WASS-3D ver. 2.0 to analyze the seawater intrusion characteristics of the incident waves in a coastal aquifer. LES-WASS-3D directly analyzed the nonlinear interaction between the seawater and freshwater in a coastal aquifer, as well as the wave-current interaction in the coastal area. First, the LES-WASS-3D results were compared with the existing experimental results for the mean water level under wave action in the coastal aquifer and seawater penetration into the coastal aquifer. The mean water level, shape and position of the seawater-freshwater interface, and intrusion distance were well implemented in the results. This confirmed the validity and effectiveness of LES-WASS-3D. The overall seawater penetration distance increases in the coastal aquifer as a result of wave set-up and run-up in the swash zone caused by continuous wave actions, and it increases with the wave height and period. Furthermore, a numerical verification was performed by comparing the suggested existing structure and newly suggested curtain wall as a measure against seawater penetration. An existing underground dam showed a better effect with increased height. Additionally, the suggested curtain wall had a better effect when the embedded depth was increased.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.6
• /
• pp.41-49
• /
• 2004

In general, open trenches or in-filled trenches have been used to isolate transmitting of vibration. Recently alternative methods, in which various materials are used for wall barriers have been proposed and performed in several sites. Although the effects of these methods are verified, resonable and qualitative evaluation methods have not yet been conducted. It may be because many factors, such as the characteristics of vibration sources, ground condition, and parameters of wall barrier are coupled complicatedly. In this study, a series of centrifugal modelings were conducted in order to examine the evaluation method of a vibration wall barrier when point load transmits to the surface. The experiments were performed with different stiffness of wall barriers and different depths of installations. Using the results obtained from tests, effects of those variables on the efficiency of vibration barrier were analyzed. Through this investigation we observed vibration transmission of under ground, and verified the applicability of ball dropping system which was developed in this study.

• Journal of the Korean housing association
• /
• v.25 no.3
• /
• pp.13-23
• /
• 2014

This study explores the daily life patterns and housing adjustment behaviors of low-income Korean elderly immigrants residing in affordable housing in the Chicago metropolitan area. Utilizing an intercultural perspective, the study focuses on identifying the immigrants' their cultural attributes of daily living and coping responses to residential misfits. These housing adjustment behaviors are classified into five modes consisting of residential mobility, structural adaptation, residential alteration, normative adaptation, and behavioral adaptation. Two-hour in-depth interviews with open-ended questions were conducted with 138 participants from 15 affordable housing complexes. Collected information includes demographic data, immigration experiences and cultural identity, daily life patterns, as well as housing evaluation and housing adjustment behaviors. The study results indicate that many research participants maintained their cultural attributes of daily living accumulated from past experiences (i.e. mostly based upon Korean cultural contexts), but also made adjustments as they complied with their aging body and new living conditions. This also reflects that immigrants' cultural needs are not limited to the use of language and ethnic goods, but are also embedded deeply in their daily life patterns to influence one's uses of the dwellings in a broader sense. All five modes of housing adjustment behaviors were observed with research participants within their residential settings. More importantly, normative and behavioral adaptations along with residential alterations occurred more simultaneously rather than sequentially when the respondents perceived discrepancy between oneself (i.e. including one's attributes, needs, and preferences) and his/her dwelling.

• Journal of The Korean Association For Science Education
• /
• v.30 no.2
• /
• pp.249-260
• /
• 2010

The main purpose of this study is to examine the effects of explicit instructions on the nature of science (NOS) on the understanding of science-gifted students. Participants were engaged in 8 explicit NOS instructions spanning 6 months. Data were collected before and after the instructions from 20 science-gifted students using student worksheets, open-ended questionnaires (Views of Nature Of Science, VNOS), and in-depth interviews. The results of this study showed that explicit instructions were helpful in improving the understanding of the tentativeness in science and socially and culturally embedded aspects of science. However, participants not only still possess naive views on the nature of science about the distinction of law and theory and the empirical aspects of science, but also had conflicting views and misconceptions in some areas. The study has implication for development of science-gifted program that the explicit instructions on NOS and science inquiry should be provided concurrently, given the complementary relationship of the two activities.

• Earthquakes and Structures
• /
• v.14 no.3
• /
• pp.273-283
• /
• 2018

Previous experimental researches indicate that reinforced concrete beam-column joints play an important role in the mechanical properties of moment resisting frame structures, so as to require proper design. In order to get better understanding of the beam-column joint performance, a rational model needs to be developed. Based on the former considerations, two typical models for calculating the shear carrying capacity of the beam-column joint including the inelastic reinforced concrete joint model and the softened strut-and-tie model are selected to be introduced and analyzed. After examining the applicability of two typical models mentioned earlier to interior beam-column joints, several adjustments are made to get better predicting of the test results. For the softened strut-and-tie model, four adjustments including modifications of the depth of the diagonal strut, the inclination angle of diagonal compression strut, the smeared stress of mild steel bars embedded in concrete, as well as the softening coefficient are made. While two adjustments for the inelastic reinforced concrete joint model including modifications of the confinement effect due to the column axial load and the correction coefficient for high concrete are made. It has been proved by test data that predicted results by the improved softened strut-and-tie model or the modified inelastic reinforced concrete joint model are consistent with the test data and conservative. Based on the test results, it is also not difficult to find that the improved beam-column joint model can be used to predict the joint carrying capacity and cracks development with sufficient accuracy.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.7
• /
• pp.2971-2977
• /
• 2014

Background: Long non-coding RNAs (lncRNAs) have been recently observed in various human cancers. However, the role of lncRNAs in pancreatic duct adenocarcinoma (PDAC) remains unclarified. The aim of this study was to detect the expression of lncRNA MALAT1 in PDAC formalin-fixed, paraffin embedded (FFPE) tissues and to investigate the clinical significance of the MALAT1 level. Methods: The expression of MALAT1 was examined in 45 PDAC and 25 adjacent non-cancerous FFPE tissues, as well as in five PDAC cell lines and a normal pancreatic epithelium cell line HPDE6c-7, using qRT-PCR. The relationship between MALAT1 level and clinicopathological parameters of PDAC was analyzed with the Kaplan-Meier method and Cox proportional hazards model. Results: The relative level of MALAT1 was significantly higher in PDAC compared to the adjacent normal pancreatic tissues (p=0.009). When comparing the MALAT1 level in the cultured cell lines, remarkably higher expression of MALAT1 was found in aspc-1 PDAC cells compared with the immortal pancreatic duct epithelial cell line HPDE6c-7 (q=7.573, p<0.05). Furthermore, MALAT1 expression level showed significant correlation with tumor size (r=0.35, p=0.018), tumor stage (r=0.439, p=0.003) and depth of invasion (r=0.334, p=0.025). Kaplan-Meier analysis revealed that patients with higher MALAT1 expression had a poorer disease free survival (p=0.043). Additionally, multivariate analysis indicated that overexpression of MALAT1, as well as the tumor location and nerve invasion, was an independent predictor of disease-specific survival of PDAC. Conclusion: MALAT1 might be considered as a potential prognostic indicator and may be a target for diagnosis and gene therapy for PDAC.