• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.235-241
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• 2009

Composite wood materials are very sensitive to water and inspection without any coupling medium of a liquid is really needed to wood materials due to the permeation of coupling medium such as water. However, air-coupled ultrasound has obvious advantages over water-coupled experimentation compared with conventional C-scanner. In this work, it is desirable to perform contact-less nondestructive evaluation to assess wood material homogeneity. A wood material was nondestructively characterized with non-contact and contact modes to measure ultrasonic velocity using automated data acquisition software. We have utilized a proposed peak-delay measurement method. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. The variation of ultrasonic velocity was found to be somewhat difference due to air-coupled limitations over conventional scan images. However, conventional C-scan images are well agreed with increasing the resin-infiltrated time as expected. Finally, we have developed a measurement system of an ultrasonic velocity based on data acquisition software for obtaining ultrasonic quantitative data for correlation with C-scan images.

• Journal of Information Management
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• v.41 no.4
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• pp.119-140
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• 2010

Methodist church materials are classified with three types, centered on the organizations manufacturing and holding materials such as 1) 'materials of the Methodist headquarter' governing all of the Methodist churches in Korea, 2) 'materials of theological seminary libraries' holding academic study books related to theology, and 3) 'materials manufactured in individual churches'. In this manner, the Methodist church materials imply homogeneity in theme, but the materials have identity from each other, because organizations are different each other, too. By a characteristic of each organizations, to use Methodist church document done a director of each organization is demanded collaboration between the material departments of each organizations, this study intends to analysis material department operation status of three Methodist church organizations. As a result of analysis, it is necessary to perform the prior tasks, such as reconstructing organization to accomplish an original function of the Methodist headquarter, developing operation regulation classified with the Methodist church group, and constructing material management system.

• Geomechanics and Engineering
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• v.34 no.6
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• pp.683-696
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• 2023

The destruction and fracture of rock masses are crucial components in engineering and there is an increasing demand for the study of the influence of rock mass heterogeneity on the safety of engineering projects. The numerical manifold method (NMM) has a unified solution format for continuous and discontinuous problems. In most NMM studies, material homogeneity has been assumed and despite this simplification, fracture mechanics remain complex and simulations are inefficient because of the complicated topology updating operations that are needed after crack propagation. These operations become computationally expensive especially in the cases of heterogeneous materials. In this study, a heterogeneous model algorithm based on stochastic theory was developed and introduced into the NMM. A new fracture algorithm was developed to simulate the rupture zone. The algorithm was validated for the examples of the four-point shear beam and semi-circular bend. Results show that the algorithm can efficiently simulate the rupture zone of heterogeneous rock masses. Heterogeneity has a powerful effect on the macroscopic failure characteristics and uniaxial compressive strength of rock masses. The peak strength of homogeneous material (with heterogeneity or standard deviation of 0) is 2.4 times that of heterogeneous material (with heterogeneity of 11.0). Moreover, the local distribution of parameter values can affect the configuration of rupture zones in rock masses. The local distribution also influences the peak value on the stress-strain curve and the residual strength. The post-peak stress-strain curve envelope from 60 random calculations can be used as an estimate of the strength of engineering rock masses.

• Analytical Science and Technology
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• v.25 no.5
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• pp.273-283
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• 2012

Phthalate plasticizers are regulated by RoHS, REACH and CPSC as hazardous substances. Responding to these international environmental restrictions, we developed ABS certified reference material (CRM) for determination of phthalate plasticizers such as DMP, DEP, DBP, BBP, DEHP and DnOP. The candidate material has been made with ABS resin widely used in electric and electronic products and 6 kinds of phthalate plasticizers. The making of the material involved a series of processes like extruding, cooling, pelletizing, and drying using twin screw extruder. Then it has been certified according to ISO Guide 35. Using isotope dilution-gas chromatography/mass spectrometry (ID-GC/MS), homogeneity, short-term stability, and long-term stability were evaluated. The certified values were determined by using primary reference material (PRM) of KRISS for traceability. From now on, we will provide ABS CRM to national and international companies and research institutes after certification as certified reference material and registering on COMAR (code of reference material).

• Analytical Science and Technology
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• v.23 no.5
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• pp.485-491
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• 2010

A certified reference material (CRM) of KRISS 109-03-SSD was developed for the analysis of hazardous elements in soil. The target elements were As, Cd, Cr, Cu, Hg, Ni, Pb, Zn being regulated by the Soil Environment Conservation Act. Starting material was collected from tailing dump of an unworked tungsten mine at Sangdong (Gangwon-do, Korea). The starting material under-went through a series of fabricating process steps of screening, drying, grinding, sieving, blending, bottling, sterilization and was certified according to the ISO Guide 35. Isotope dilution-inductively coupled mass spectrometry (ID-ICP/MS) and instrumental neutron activation analysis (INAA) were used for the measurement. Homogeneity was tested according to ISO 13528 annex B. The certified values were determined using the results from two different methods or from two independent measurements using a method. Finally, certified values of seven elements of arsenic, cadmium, chromium, copper, lead, nickel and zinc were determined. Mercury did not satisfied the criteria of homogeneity and the result would be provided for information only, together with iron and tungsten. It was also studied, the extractable fraction of elements by aqua regia according to the ISO 11466 protocol being frequently studied for the purpose of environmental monitoring. It was performed as a inter-laboratory study by 6 laboratories of a public institute and universities. Standard deviation among the laboratories was much bigger than the uncertainty of the certified value. The result of inter-laboratory study on the extractable fraction will be provided for information, only.

• Analytical Science and Technology
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• v.37 no.3
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• pp.166-173
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• 2024

Steroids have a temporary skin improvement and whitening effect by controlling vasodilation, but they also cause side effects when used for a long time. Therefore, steroids were designated and managed as raw materials that cannot be used in cosmetics in Korea. However, steroids are continuously being detected in cosmetics, causing social issues. In this study, we developed a certified reference material (CRM) for the determination of steroids such as hydrocortisone in cosmetics. A cream-type cosmetic CRM was manufactured and subsequently certified following the guidelines outlined in ISO Guide 35. Homogeneity, short-term stability, and long-term stability were evaluated using isotope dilution mass spectrometry (ID-MS). The certified values were determined by using NIST's primary reference material to ensure traceability. From now on, we intend to supply the certified reference material as a cosmetic CRM to national and international companies, as well as research institutes after certification as certified reference material from KOLAS and registering on COMAR.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1645-1647
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• 1999

Epoxy compound has been used as insulation material in electrical equipment because of its properties 1) Nowadays, becoming higher voltage system, the properties of interface between epoxy and its metal insert become more important. In this paper, we suggest two types semiconducting paste. One is epoxy type and the other is olephine type. After sprayed the semiconducting paste on metal insert sanded, we procedure the test one is the adhesion strength test, the other is electrical breakdown strength test. So we knew that the epoxy type paste became more higher adhesion strength than olephine type paste because of its homogeneity at the interfaces. And at the breakdown strength test, olephine type paste became less higher than epoxy type paste because of its volatility. So in this study, we suggest the optimum interface condition by adjusting the semiconducting paste and surface roughness.

• Journal of architectural history
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• v.23 no.4
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• pp.7-17
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• 2014

This paper aims at researching the cave concept of the Japanese architect Terunobu Fujimori and the result could be summarised as follows. First, a cave is Fujimori's only theme related to the interior space. He set some design guidelines for practice concerning openings of the wall and finishing materials of the interior, following the two major characteristics of a cave: 'comfortability' and 'homogeneity in material'. And 'fire' was also the premise in the cave as a 'spirit' of the space. Second, Fujimori applied the concrete guidelines to Tanpopo House (1994~95), which had in fact borne the ideas. Yakisugi House (2005~07) that took the cave as its design theme showed the transition of his cave concept, from closedness to openness. Third, though his cave concept might deserve the criticism that it is inclined to 'image' rather than 'essence', it illustrates that he seeks after an archetype of human dwelling before the purity of the original space was tarnished with rationality and abstraction. And the cave idea allows the seemingly contradictory 'sachlich' and 'surrealistic' features to coexist. Summing up, Fujimori's cave concept proves that his architecture is a rejection of the Cartesian modernist ideal and the contemporary architects' desire for dematerialisation. In a fundamental level, however, it is a result of his strategic choice induced by his own primary principle that his building must not be similar to any styles in history or any other architects' works in the world.

• Journal of the Korean Ceramic Society
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• v.45 no.9
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• pp.507-511
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• 2008

A "C-sphere" specimen geometry was used to determine the failure strength distributions of a commercially-available bearing-grade silicon nitride ($Si_3N_4$) with ball diameters of 12.7 and 25.4 mm. Strengths for both diameters were determined using the combination of failure load, C-sphere geometry, and finite element analysis and fitted using two-parameter Weibull distributions. Effective areas of both diameters were estimated as a function of Weibull modulus and used to explore whether the strength distributions predictably scaled between each size. They did not. That statistical observation suggested that the same flaw type did not limit the strength of both ball diameters indicating a lack of material homogeneity between the two sizes. Optical fractography confirmed that. It showed there were two distinct strength-limiting flaw types common to both ball diameters, that one flaw type was always associated with lower strength specimens, and that a significantly higher fraction of the 25.4-mm-diameter C-sphere specimens failed from it. Predictable strength-size-scaling would therefore not result as a consequence of this because these flaw types were not homogenously distributed and sampled in both C-sphere geometries.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.263-266
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• 2003

This research investigated the process of removing cadmium and tested the detoxification mechanism of the cadmium-binding peptide (Cd-BP) from Rumex crispus. Phytochelatin-like cadmium-binding peptide (PC-Cd-BP) of Rumex crispus was purified and identified. Rumex crispus was exposed to 4.3 mg Cd/L for seven days. Heat-treated supernatant fraction taken by root tissues showed traces of PC-Cd-BP An analysis of the material through Gel-filteration chromatography on the Sephadex G-75 column showed two symmetrical Cd-BP peaks. The major peak with the smaller molecular weight was further purified by $C_{18}$ reverse-phase HPLC to produce apparent homogeneity. The amino acid composition of Cd-BP from Rumex crispus included cysteine (22.6%), glutamate and glutamate acid (20%), and glycine (12%). It was similar the amino acid composition of most PC. The molecular weight of the purified peptide was determined at 568-706 Da by MALDI-TOF MS. Therefore, the Cd-BP of Rumex crispus was PC-Cd-BP consisting of isopeptides.