• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1126-1126
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• 2001

The paper presented here is the initial part of a larger study, in which it was determined which quality parameters in cheese powder could already be predicted by NIR at an early stage in the process and which could only be predicted at the final stages of the process. This initial study was performed in order to establish the levels and nature of variation within and between batches such that the subsequent data collection could be tackled optimally. The perspectives evolved into more than was originally planned and revealed some interesting uses of NIR-technology. Cheese powder production starts as a batch process, where waste cheese from other dairies is melted down in a vat. The process then turns into a continual process as the vat is emptied and the melted cheese is then filtered, homogenized, pasteurized and finally spray dried. Between each batch the powder is to a greater or lesser degree a mixture of 2 batches. This paper is divided into 2 aspects, one regarding the optimization of sampling time and the other is a study of process dynamics. Optimizing sampling time This initial study included 9 powder samples from 9 different batches produced during one day. The raw materials for the batches were chosen with the aim of creating a relatively high level of variation in the data. The total of 81 samples were taken out at regular intervals and spectra were collected on a NIR-systems 6500 instrument. The subsequent reduction of the data by PCA to score values shows the power of NIR as a tool to determine not only when samples are representative of a certain batch, but also which batches are stable enough to include in a further study. Studying process dynamics To take this experiment a step further 1 of the 81 samples were sent to the laboratory for further analyses. The samples were chosen on the criteria that they covered the spectral variation in the dataset. These samples were analysed for 4 chemical components and 5 physical attributes, which are essential for describing the quality of the product. The latent structure of the 7 samples, using the chemical and physical variables, is totally comparable to the latent structure of the NIR spectra. This outcome makes it possible to describe the dynamics of one day's production both chemically and physically with relatively little resources. Additionally it raises the question as to whether reference values are needed, as the latent structure of the NIR-spectra appears to be sufficient in providing information on the quality of the product. To be able to use NIR in this way would require defining quality limits in the principal component space as opposed to each of the reference values. The potential of NIR applied in an explorative fashion with batch processes opens a whole new gateway for the use of this technology. This study explains yet again after so many years in the field “why I'm crazy about NIR!”.

• Journal of Korean Society of Rural Planning
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• v.19 no.4
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• pp.17-32
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• 2013

Reckless development policy, which has continued during the past several decades, caused landscape damage. In order to solve this problem, it is very urgent to conserve the habitat and to establish systematic database. Recently, various researches related to landscape damage have been conducted actively and the necessity of landscape ecological planning based on the biotop mapping has been issued as one of the solutions. Therefore, the purpose of this study is to select the study area, which is located in Guji-meon, Dalseong-gun, Daegu and will be formed into Daegu Science Park, and then to develop and apply the landscape ecological planning model based on biotop mapping in district unit. The results are as follows. Fist of all, according to the results of biotop classification with field survey and literature review, total 13 biotop and total 63 biotop types were classified. According to the first evaluation with B-VAT, total 19 biotop types were classified I grade including natural river with abundant plants(BA) and so on. While V grade, which has lowest value, was classified 16 biotop types including vegetable garden adjacent to river(BC). Also the second evaluation, we analyzed total 30 areas such as 1a, 1b grades, which had special meaning for the conservation of species and biotop. Next, 2a, 2b, 2c grades were analyzed total 82 areas. Secondly, in the compliance with Ecological landscape planning, we divided landscape planning model into two parts such as setting of improvement goal and detailed implement plan. For instance, setting of improvement goal, we classified 9 parts such as conservation region and parts of detailed implement plan, we classified total 28 planning indicators with 4 view such as the region which should be special protected from nature and landscape. Lastly, with the developed landscape model we applied to research areas, made maps, and differentiate proposals in each region. Specially, the final master plan was made to help understand the contents of detailed landscape planning. This study will be a useful data, which can solve the landscape damage problem systematically and control it landscape-friendly with biotop classification, evaluation, landscape ecological planning model, and application method which we developed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.153-162
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• 2020

Objectives: 3D printing technologies have become widely developed and are increasingly being used for a variety of purposes. Recently, the evaluation of 3D printing operations has been conducted through chamber test studies, and actual workplace studies have yet to be completed. Therefore, the objective of this study was to determine the emission of volatile organic compounds(VOCs), metals, and particles from printing operations at a workplace. This included monitoring conducted at a commercial 3D printing service workplace where the processes involved material extrusion, material jetting, binder jetting, vat photo polymerization, and powder bed fusion. Methods: Area samples were collected with using a Tenax TA tube for VOC emission and MCE filter for metals in the workplace. For particle monitoring, Mini Particle Samplers(MPS) were also placed in the printer, indoor work area, and outdoor area. The objective was to analyze and identify particles' size, morphology, and chemical composition using transmission electron microscopy with energy dispersive spectroscopy(TEM-EDS) in the workplace. Results: The monitoring revealed that the concentration of VOCs and metals generated during the 3D printing process was low. However, it also revealed that within the 3D printing area, the highest concentration of total volatile organic compounds(TVOC) was 4,164 ppb at the vat photopolymerization 3D printing workplace, and the lowest was 148 ppb at the material extrusion 3D printing workplace. For the metals monitoring, chromium, which, is carcinogenic for humans, was detected in the workplace. As a characteristic of the particles, nano-sized particles were also found during the monitoring, but most of them were agglomerated with large and small particles. Conclusions: Based on the monitoring conducted at the commercial 3D printing operation, the results revealed that the concentration of VOCs and metals in the workplace were within Korea's occupational exposure limits. However, due to the emission of nano-sized particles during 3D printing operations, it was recommended that the exposure to VOCs and metals in the workplace should be minimized out of concern for workers' health. It was also shown that the characteristics of particles emitted from 3D printing operations may spread widely within an indoor workplace.

• Journal of the Korean Dietetic Association
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• v.9 no.2
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• pp.128-137
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• 2003

The purposes of this study were to investigate the current status of contracted hospital food services and to find out the difference in accordance with the number of beds in hospitals. Thirty six hospitals having more than 100beds in Seoul, Inchon and Kyungkido were the subjects of this study. Data was collected through surveys. The survey was conducted during March and April in 2002. The Questionnaires were mailed to the 36 directors of dietetic departments of the hospitals and 36 managers of contracting patient food services. Statistical analysis was completed using SPSS Win(11.0) for descriptive analysis and t-test. The results of the study are summerized as follows; Ⅰ. Hospital perspective : The range covered by contract food service was 63.3% and 36.7% in hospital food services, and medical nutrition services. The patient and employee food services were in 83.3%, and patient food services were in 6.7%. The methods selecting contractors are general, limited, selected and competitive biddings, and private contracts. The responsibility for supervision of contract food services was the dietetic department (51.7%) in most cases. Hospitals having personnel responsible for contracting affairs were in 75.9% of the cases and 24.1% did not have personnel. The biggest reason for contracting was facilitation of personnel management. The most important criteria on selecting food services contractors was the professionality of the contractor. Ⅱ. Contractor's perspective : The cost per meal in the year 2001 was composed of 1,905 won for food cost, 1,081 won for labor cost, 222 won for expenses, 114 won for VAT, 14 won for rent and 146 won for miscellaneous or controllable expense, representing 109 won loss per meal. The profit-and-loss contract cost is higher than the fee-contract cost. The ratios of food cost, labor cost and expenses are higher and the ratios of miscellaneous or controllable expense, VAT, rent and profit are lower in hospitals with more than 400 beds compared with those less than 400 beds. However, no significant differences are present between these two groups of hospitals. The actual contract period was 2.2 years upon initial contract and 1.2 years upon renewal. The initial investment cost was 53 million won and the cost of renovation and repair was 8.5 million won. Significant differences were present between two groups of hospitals. The conditions of employment and number of personnel hired by contractors for contract patient food services were significantly different according to the number of beds.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.1
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• pp.1-15
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• 2021

Additive manufacturing (AM) for dental materials can produce more complex forms than conventional manufacturing methods. Compared to milling processing, AM consumes less equipment and materials, making sustainability an advantage. AM can be categorized into 7 types. Polymers made by vat polymerization are the most suitable material for AM due to superior mechanical properties and internal fit compared to conventional self-polymerizing methods. However, polymers are mainly used as provisional restoration due to their relatively low mechanical strength. Metal AM uses powder bed fusion methods and has higher fracture toughness and density than castings, but has higher residual stress, which requires research on post-processing methods to remove them. AM for ceramic use vat polymerization of materials mixed with ceramic powder and resin polymer. The ceramic materials for AM needs complex post-processing such as debinding of polymer and sintering. The low mechanical strength and volumetric accuracy of the products made by AM must be improved to be commercialized. AM requires more research to find the most suitable fabrication process conditions, as the mechanical properties and surface of any material will vary depending on the processing condition.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.71
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• pp.245-265
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• 2016

A number of Chinese students who are studying in Korea have been gradually increasing since Korea and China established diplomatic relations. Many of them sale Korean products to China while studying for their degree programs in colleges. This kind of transactions can be named C2C overseas direct sales. C2C overseas direct sales which are being performed by Chinese student are good for exportation of Korean products. However Some of these transactions are not legal according to present law, First, Chinese student don't have legal status to make the transactions. Second, Chinese students usually make false declarations for evading the taxes, including tariff and VAT, Third, Chinese students can not offer the after-sale service for the goods for the Chinese consumers. Although C2C transactions have some legal matters, they should not be banned by a one-size-fits-all method. In this study, we highly recommend for the development of C2C transactions, First, Korean government should give Chinese students legal status. Second, China customs must strictly prohibit illegal activities of smuggling by taking advantage of postal route. Third, sellers in China can offer the after-sale service to consumers through some specialist A/S firms.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.914-917
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• 2001

The rice water weevil, Lissorhoptrus oryzophillus are major pests of aquatic rice plant throughout the country. In field, we examined efficacy of Steinernema carpocapsae and Xenorhabdus nematophilus against rice water weevil, Lissorhoptrus oryzophilus. Steinernema carpocapsae showed 71-74.2% mortality after 15days in the field. Also symbiotic bacteria Xenorhabdus nematophilus isolated from Steinernema carpocapsae showed 33.3-58.3% mortality after 15days at vat against rice water weevil, Lissorhoptrus oryzophilus.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.100-107
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• 2017

3D printing is a technology that converts a computer-generated 3D model into a real object with additive manufacturing technology. A majority of 3D printing technologies uses one material, and this is considered a limitation. In this study, we developed a multi-material 3D printer by adopting dual resin vat and cleaning system with DLP (Digital Light Processing) 3D printing technology. The developed multi-material DLP 3D printer is composed of a manufacturing system, cleaning system, transporting system, and automatic resin recharging system. Various 3D structures were 3D printed with two materials, thus demonstrating the potential. Printing performance of the multi-material DLP 3D printer was studied by performing a comparative surface roughness test and tension test on specimens composed of one material as well as those composed of two materials.

• New & Renewable Energy
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• v.7 no.3
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• pp.92-100
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• 2011

With the increased demand of clean energy and global warming measures, the renewable energy development has been increased recently. The TCP (Tidal Current Power) is one of the ocean renewable energy sources. Having the high tidal energy source in Korea, there are many potential TCP sites with strong current speed. The rotor, which initially converts the energy, is a very important component because it affects the efficiency of the entire system. The rotor performance is determined by various design parameters including number of blades, shape, sectional size, diameters and etc. However, the interactions between devices also contribute significantly to the energy production. The rotor performance considering the interaction needs to be investigated to predict the exact power in the farm. This paper introduces the optimum design of TCP turbine and the performance of devices considering the interference between rotors.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.63-68
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• 2009

The urgent VAI method development is required since "The Act of Physical Protection and Radiological Emergency that is established in 2003" requires an evaluation of physical threats in nuclear facilities and an establishment of physical protection in Korea. The VAI methodology is developed to (1) make a sabotage model by reusing existing fire/flooding/pipe break PSA models, (2) calculate MCSs and TEPSs, (3) select the most cost-effective TEPS among many TEPSs, (4) determine the compartments in a selected TEPS as vital areas, and (5) provide protection measures to the vital areas. The developed VAI methodology contains four steps, (1) collecting the internal level 1 PSA model and information, (2) developing the fire/flood/pipe rupture model based on level 1 PSA model, (3) integrating the fire/flood/pipe rupture model into the sabotage model by JSTAR, and (4) calculating MCSs and TEPS. The VAT process is performed through the VIPEX that was developed in KAERI. This methodology serves as a guide to develop a sabotage model by using existing internal and external PSA models. When this methodology is used to identify the vital areas, it provides the most cost-effective method to save the VAI and physical protection costs.