• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2005.11a
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• pp.45-53
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• 2005

A novel method for evaluating the anisotropy of the deterministic features in a stochastic 2D data is introduced. The ability of the wavelet transform for the identification of the abrupt discontinuities could be used to characterize the boundary of the deterministic area in a 2D stochastic data, such as flocs in paper structure. The one-dimensional wavelet transform with a small-scale range in MD and CD could quantify the amount of the edge in both directions, depending on the intensity of each floc. The flocs that are aligned in the MD direction result in a higher value of local wavelet energy in the CD direction. Therefore, the ratio of the total wavelet energy in CD and MD directions can be used as a new anisotropy index. This index is a measure of the floc-orientation and can provide an excellent tool to obtain the orientation distribution and the major oriented angle of flocs. Various simulated images and real stochastic data such as local gloss variation of printed image and formation image, have been tested and the results show this analysis method is very reliable to measure the anisotropy of the deterministic features.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.405-410
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• 2018

TiN and CrN thin films are among the most used coatings in machine and tool steels. TiN and CrN are deposited by arc ion plating(AIP) method. The AIP method inhibits the reaction by depositing a hard, protective coating on the material surface. In this study, the characteristics of multi-layer(TiN/CrN/TiN(TCT), CrN/TiN/CrN(CTC)) are investigated. For comparison, TiN with the same thickness as the multilayer is formed as a single layer and analyzed. Thin films formed as multilayers are well stacked. The characteristics of micro hardness and corrosion resistance are better than those of single layer TiN. The TiN/CrN peak is confirmed because both TCT and CTC are formed of the same component(TiN, CrN), and the phase is first grown in the (111) direction, which is the growth direction. However, the adhesion and abrasion resistance of the multilayer films are somewhat lower.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3998-4002
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• 2012

With continuing progress of nanotechnologies and various applications of nanoparticles, one needs to develop a quick and fairly standard assessment tool to evaluate cytotoxicity of nanoparticles. However, much cytotoxicity studies on the interpretation of the interaction between nanoparticles and cells are non-mechanistic and time-consuming. Here, we propose a simple screening method for the analysis of the interaction between several AgNPs (5.3 to 64 nm) and fluorescence-dye containing vesicles ($12{\mu}m$) acting as a biomimetic cell-membrane. Fluorescence-dye containing vesicle was prepared using a fluorescence probe (1,6-diphenyl-1,3,5-hexatryene), which was intercalated into the lipid bilayer due to their hydrophobicity. Zeta potential of all materials except for bare-AgNPs (+32.8 mV) was negative (-26 to -54 mV). The morphological change (i.e., rupture and fusion of vesicle, and release of dye) after mixing of the vesicle and AgNPs was observed by fluorescence microscopy, and fluorescence image were different with coating materials and surface charge of x-AgNPs. In the results, we found that the surface charge of nanoparticles is the key factor for vesicle rupture and fusion. This proposed method might be useful for analyzing the cytotoxicity of nanoparticles with cell-membranes instead of in vitro or in vivo cytotoxicity tests.

• Advances in concrete construction
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• v.1 no.3
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• pp.201-213
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• 2013

While recognizing the problem of reinforcement corrosion and premature structural deterioration of reinforced concrete (RC) structures as a combined effect of mechanical and environmental actions (carbonation, ingress of chlorides), emphasis is given on the effect of the latter, as most severe and unpredictable action. In this study, a simulation tool, based on proven predictive models utilizing principles of chemical and material engineering, for the estimation of concrete service life is applied on an existing reinforced concrete bridge (${\O}$resund Link) located in a chloride environment. After a brief introduction to the structure of the models used, emphasis is given on the physicochemical processes in concrete leading to chloride induced corrosion of the embedded reinforcement. By taking under consideration the concrete, structural and environmental properties of the bridge investigated, an accurate prediction of its service life is taking place. It was observed that the proposed, and already used, relationship of service lifetime- cover is almost identical with a mean line between the lines derived from the minimum and maximum critical values considered for corrosion initiation. Thus, an excellent agreement with the project specifications is observed despite the different ways used to approach the problem. Furthermore, different scenarios of concrete cover failure, in the case when a coating is utilized, and extreme deicing salts attack are also investigated.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.672-677
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• 2020

Expensive PCBN or ceramic cutting tools are used for the processing of difficult-to-cut materials such as Ti and Ni alloy materials. These tools have a problem of breaking easily due to their high hardness but low fracture toughness. To solve this problem, cutting tools that form various coating layers are used in low-cost WC-Co hard material tools, and researches on various tool materials are being conducted. In this study, WC-5, 10, and 15 wt%Ni hard materials for difficult-to-cut cutting materials are densified using horizontal ball milled WC-Ni powders and pulsed current activated sintering method (PCAS method). Each PCASed WC-Ni hard materials are almost completely dense, with a relative density of up to 99.7 ~ 99.9 %, after the simultaneous application of pressure of 60 MPa and electric current for 2 min; process involves almost no change in the grain size. The average grain sizes of WC and Ni for WC-5, 10, and 15 wt%Ni hard materials are about 1.09 ~ 1.29 and 0.31 ~ 0.51 µm, respectively. Vickers hardness and fracture toughness of WC-5, 10, and 15 wt%Ni hard materials are about 1,923 ~ 1,788 kg/mm2 and 13.2 ~ 14.3 MPa.m1/2, respectively. Microstructure and phase analyses of PCASed WC-Ni hard materials are performed.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.39-44
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• 2022

Using a CFD (computational fluid dynamics) simulation tool, we have offered a design guideline of a slot-die head having a simple T-shaped cavity through an analysis of the fluid dynamics in terms of cavity pressure and outlet velocity, which affect the uniformity of coated thin films. We have visualized the fluid flow with a transparent slot-die head where poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is injected. We have shown that the fluid dynamics inside the slot-die head depends sensitively on the cavity depth, cavity length, land length, and channel gap (i.e., shim thickness). Of those, the channel gap is the most critical parameter that determines the uniformity of the pressure and velocity distributions. A pressure drop inside the cavity is shown to be reduced with decreasing shim thickness. To quantify it, we have also calculated the coefficient of variation (CV). In accordance with Hagen-Poiseuille's laws and electron-hydraulic analogy, the CV value is decreased with increasing cavity depth, cavity length, and land length.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.421-430
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• 2004

Clinically, it is almost impossible for a physician to distinguish subtle changes of frequency spectrum by using a stethoscope alone especially in the early stage of thrombus formation. Considering that reliability of mechanical valve is paramount because the failure might end up with patient death, early detection of valve thrombus using noninvasive technique is important. Thus the study was designed to provide a tool for early noninvasive detection of valve thrombus by observing shift of frequency spectrum of acoustic signals with computer aid diagnosis system. A thrombus model was constructed on commercialized mechanical valves using polyurethane or silicon. Polyurethane coating was made on the valve surface, and silicon coating on the sewing ring of the valve. To simulate pannus formation, which is fibrous tissue overgrowth obstructing the valve orifice, the degree of silicone coating on the sewing ring varied from 20％, 40％, 60％ of orifice obstruction. In experiment system, acoustic signals from the valve were measured using microphone and amplifier. The microphone was attached to a coupler to remove environmental noise. Acoustic signals were sampled by an AID converter, frequency spectrum was obtained by the algorithm of spectral analysis. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. A return map was applied to evaluate continuous monitoring of valve motion cycle. The in-vivo data also obtained from animals with mechanical valves in circulatory devices as well as patients with mechanical valve replacement for 1 year or longer before. Each spectrum wave showed a primary and secondary peak. The secondary peak showed changes according to the thrombus model. In the mock as well as the animal study, both spectral analysis and 3-layer neural network could differentiate the normal valves from thrombosed valves. In the human study, one of 10 patients showed shift of frequency spectrum, however the presence of valve thrombus was yet to be determined. Conclusively, acoustic signal measurement can be of suggestive as a noninvasive diagnostic tool in early detection of mechanical valve thrombosis.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.06a
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• pp.16-23
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• 2000

The increasing functional needs of top-quality printing papers and packaging paperboards, and especially the rapid developments in electronic printing processes and various computer printers during past few years, set new targets and requirements for modern paper quality. Most of these paper grades of today have relatively high filler content, are moderately or heavily calendered , and have many coating layers for the best appearance and performance. In practice, this means that many of the traditional quality assurance methods, mostly designed to measure papers made of pure. native pulp only, can not reliably (or at all) be used to analyze or rank the quality of modern papers. Hence, introduction of new measurement techniques is necessary to assure and further develop the paper quality today and in the future. Paper formation , i.e. small scale (millimeter scale) variation of basis weight, is the most important quality parameter of paper-making due to its influence on practically all the other quality properties of paper. The ideal paper would be completely uniform so that the basis weight of each small point (area) measured would be the same. In practice, of course, this is not possible because there always exists relatively large local variations in paper. However, these small scale basis weight variations are the major reason for many other quality problems, including calender blacking uneven coating result, uneven printing result, etc. The traditionally used visual inspection or optical measurement of the paper does not give us a reliable understanding of the material variations in the paper because in modern paper making process the optical behavior of paper is strongly affected by using e.g. fillers, dye or coating colors. Futhermore, the opacity (optical density) of the paper is changed at different process stages like wet pressing and calendering. The greatest advantage of using beta transmission method to measure paper formation is that it can be very reliably calibrated to measure true basis weight variation of all kinds of paper and board, independently on sample basis weight or paper grade. This gives us the possibility to measure, compare and judge papers made of different raw materials, different color, or even to measure heavily calendered, coated or printed papers. Scientific research of paper physics has shown that the orientation of the top layer (paper surface) fibers of the sheet paly the key role in paper curling and cockling , causing the typical practical problems (paper jam) with modern fax and copy machines, electronic printing , etc. On the other hand, the fiber orientation at the surface and middle layer of the sheet controls the bending stiffness of paperboard . Therefore, a reliable measurement of paper surface fiber orientation gives us a magnificent tool to investigate and predict paper curling and coclking tendency, and provides the necessary information to finetune, the manufacturing process for optimum quality. many papers, especially heavily calendered and coated grades, do resist liquid and gas penetration very much, bing beyond the measurement range of the traditional instruments or resulting invonveniently long measuring time per sample . The increased surface hardness and use of filler minerals and mechanical pulp make a reliable, nonleaking sample contact to the measurement head a challenge of its own. Paper surface coating causes, as expected, a layer which has completely different permeability characteristics compared to the other layer of the sheet. The latest developments in sensor technologies have made it possible to reliably measure gas flow in well controlled conditions, allowing us to investigate the gas penetration of open structures, such as cigarette paper, tissue or sack paper, and in the low permeability range analyze even fully greaseproof papers, silicon papers, heavily coated papers and boards or even detect defects in barrier coatings ! Even nitrogen or helium may be used as the gas, giving us completely new possibilities to rank the products or to find correlation to critical process or converting parameters. All the modern paper machines include many on-line measuring instruments which are used to give the necessary information for automatic process control systems. hence, the reliability of this information obtained from different sensors is vital for good optimizing and process stability. If any of these on-line sensors do not operate perfectly ass planned (having even small measurement error or malfunction ), the process control will set the machine to operate away from the optimum , resulting loss of profit or eventual problems in quality or runnability. To assure optimum operation of the paper machines, a novel quality assurance policy for the on-line measurements has been developed, including control procedures utilizing traceable, accredited standards for the best reliability and performance.

• The Korean Journal of Pesticide Science
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• v.5 no.2
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• pp.1-12
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• 2001

A competitive indirect enzyme-linked immunosorbent assay (ci ELISA) for the organophosphorus insecticide acephate, O,S-dimethyl acetylphosphoramidothioate, was developed using a polyclonal antibody. Three different haptens mimicking the analyze and containing hexanoic acid moiety as a linker were synthesized, and then conjugated with the carrier proteins bovine serum albumin and keyhole limpet hemocyanin by the N-hydroxysuccinimide active ester method. Polyclonal antibodies raised against hapten-KLH conjugates in rabbits and the hapten-BSA conjugates as coating antigens were screened and selected for the assay in the homologous and/or heterologous ELISA system. The effects of various assay conditions, including blocking reagents, detergent content, organic solvents, pH, and preincubation of tile mixture of the polyclonal antibody and the analyze on the sensitivity were evaluated. The $IC_{50}$ value of acephate of 110 ng/mL was obtained in an optimized heterologous system using hapten-3-BSA as a coating antigen and a polyclonal antibody 8377, showing the detection range of 10-1000 ng/mL and the lowest detection limit of 4 ng/mL. The cross-reactivities of the structurally related insecticides, including methamidophos were less than 0.02%. These results indicate that the ELISA could be a convenient and alternative tool for monitoring acephate residues in agricultural products and environmental samples.

• International Journal of Advanced Culture Technology
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• v.5 no.3
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• pp.24-34
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• 2017

Nail art is a kind of nail painting or decoration that adds to the beauty. Throughout making nail art, the worker was on a dusty operation with the smoothing of chemicals and nails. People working at nail shops not only use a variety of chemicals, but also experience a lot of fine powder during the process of nail trimmings. While drying the chemical adhesive, the workers often complain of eye, nose and throat discomfort. In addition, the acrylic brush is characterized by a lot of smell when washed with washing solution. Also nail art workers directly influence the worker's breathing through the work done by placing the guest's hands in a work space called a nail table. Chemical ingredients used in nail art procedures include acetone, ethyl acetic acid, toluene, butyl acetic acid, glue, and top coating of nail varnishes. Prolonged inhalation of these substances may cause dizziness, vomiting, as well as impaired respiratory system. The purpose of this study is to investigate the respiratory symptoms of nail shop workers who are likely to be affected by work in nail shop and to find out which factors have the greatest influence if they have respiratory symptoms. Therefore this study is to provide basic data on the health management system of people engaged in nail shop and to develop health education program. For this study, the data collection was collected on July 7, 2017 for the nail shop workers attending the nail art trend seminar held in Gwangju, in Korea. The data were all 236. However, except for the poor data, 208 data were used for the final analysis. The questionnaire consisted of 30 in general questions, questions about self-efficacy in 24 questions. elf-efficacy measuring tool developed by A.Y, Kim, I. Y, Park(2001). The self-efficacy questionnaire consists of 24 items and is self-reported 7-point Likert scale. The reliability of this tool was cronbach alpha = .934.The collected data were analyzed using spss 18.0. Information of Research participant performed frequency analysis. To examine the effects of personal characteristics on self-efficacy, $X^2$ analysis was conducted. And also $X^2$ analysis was conducted to analyze the coughing symptom appearance according to individual and environmental factors. A hierarchical regression analysis was used to determine which of the personal and environmental factors influenced cough symptoms.