• Journal of Food Hygiene and Safety
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• v.6 no.1
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• pp.27-40
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• 1991

;ABSTRACT-The effects of gastric ulcer induced by restraint and water-immersion stress on gastric carcinogenesis in Wistar male rats treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined. Rats of group 1 were 2iven stress for 8 hours before they were received MNNG (100 mg/l) in drinking water for 20 weeks. Rats of group 2 were received MNNG first for 2 weeks and then were given stress once a week from 3rd to 12th weeks, with simultaneous MNNG adminitration and followed by MNNG only until 20th weeks. Rats of group 3 were received MNNG only as a positive control and rats of group 4 were not treated with carcinogen. All groups were sacrificed in 20 weeks. Sections of the pyloric mucosa were stained by avidin-biotin peroxidase complex (ABC) immuno-histochemical method. PAPG (pepsinogen isozyme 1 altered pyloric gland), body weight change, gross lesions and histopathological changes were examined. The results obtained from these studies were summarized as follows: 1. The mean body weight gains of the rats fed with carcinogens (group 1, 2, 3) were significantly lower than that of group 4 (control group, without carcinogen. p<0.05). However, the differences of the mean body weight of rats treated with carcinogen were not significant. 2. Stress treatment (group 1 and 2) increased the appearance of the numbers of PAPG (Pepsinogen 1 Altered Pyloric Gland) induced by carcinogen significantly compared with that of group 3 (carcinogen only, p<0.01). 3. The incidence rate of mucosal hyperplasia in pylorus was significantly increased in group 2 compared with group 3 (p<0.05).0.05).

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.1-12
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• 2011

To improve the mechanical properties, such as durabilities and antioxidative characteristics, the covalently cross-linked (CL-) SPEEK (sulfonated polyether ether ketone)/Cs-substituted HPA (heteropoly acid) organic-inorganic composite membranes (CL-SPEEK/Cs-HPAs), have been intensively investigated. The composite membrane were prepared by blending cesium-substituted HPAs (Cs-HPAs), including tungstophosphoric acid (TPA), molybdophosphoric acid (MoPA), and tungstosilicic acid (TSiA) with cross-linking agent content of 0.01 mL. And composite electrolytes composed of Cs-HPAs, prepared by immersion (imm.) and titration (titr.) methods to increase the stability of HPAs in water, were applied to polymer electrolyte membrane electrolysis (PEME). As a result, the proton conductivity of Cs-substituted composite membranes increased rapidly over $60^{\circ}C$ but mechanical properties, such as tensile strength, decreased in accordance with added Cs content. The bleeding-out of Cs-TPA membranes by titration method (50 vol.% Cs) decreased steadily to 2.15%. In the oxidative stability test by Fenton solution, the durability of membranes with Cs-HPA significantly increased. In case of CL-SPEEK/ Cs-TPA membrane, duration time increased more than 1200 hours. It is expected that even though CL-SPEEK/Cs-MoPA membrane shows the high proton conductivity, electrocatalytic activity and cell voltage of 1.80 V for water electrolysis, the CL-SPEEK/Cs-TPA (imm.) is more suitable as an alternative membrane in real system with the satisfactory proton conductivity, mechanical properties, anti-oxidative stability and cell voltage of 1.89 V.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.39-49
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• 1986

The purpose of this study was to observe characteristic properties through the polarization curves and SEM images from 4 different types of amalgam obtained by using the potentiostats (Princeton EG & G) & SEM (Jeol/35), and to investigate the degree of corrosion on the oxidation peak of the each phase of amalgam. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by means of the mechanical amalgamator (Shofu Co.), the triturated mass was inserted into the cylindrical metal mold which was 12mm in diameter and 10.0mm in height and was condensed by using routine manner. The specimen was removed from the mold and stored at room temperature for about 24 hours. The standard surface preparation was routinely carried out. Anodic polarization measurement was employed to confirm the corrosion behaviour of the amalgams in a 0.9% saline solution (P.H: 6.8-7.0) at $37^{\circ}C$. The initial rest potential (corrosion potential) was determined after 30 minutes of immersion of specimen in electrolyte, and the potential scan was begun at the point of 100mV cathodic from the corrosion potential. The scan rate was 0.17mV/sec. in the study to observe the degree of corrosion of each phase. SEI and EPMA images on the determined oxidation peaks of each amalgam were observed. The results were as follows: 1. In the four anodic polarization curves, low copper amalgams have three oxidation peaks and high copper amalgams have two oxidation peaks, -270mV, +26mV and +179mV(SEC) in the low copper lathe cut, and -300mV, +39mV and +163mV(SEC) in the low copper spherical. -4mV and +154mV(SEC) in the Dispersalloy, and +17mV and +180mV(SEC) in the Tytin as high copper amalgams. 2. ${\gamma}_2$ phase in the low copper amalgam and ${\eta}$ phase in the high copper amalgam were the most corrodible phases and Ag-Cu eutectic in high copper amalgam was the most slowly corroded phase. 3. Low copper amalgam was more susceptible in corrosion than high copper amalgam.

• Journal of the Korea Computer Graphics Society
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• v.26 no.3
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• pp.111-121
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• 2020

Realistic training contents utilizing intensive immersion of virtual reality are being used in various fields such as industry, education, and medical care. High-risk, high-cost education training, in particular, is difficult to conduct in reality, but it can be applied with the latest virtual reality technology that enhances educational effectiveness by efficiently and safely experiencing it in an environment similar to reality. This study introduces a management system that systematically manages realistic virtual training contents and visualizes training results in schematic pictures based on defined evaluation elements. The management system can store the information generated from the content in the database and manage the training records of each trainee in a practical way. In addition, a content-based scenario can be created in multiple scenarios by setting training goals, number of participants, and methods for applying evaluation elements. This paper describes the management system's production method and the results based on the virtual reality training content as an application example.

• The Journal of Korean Academy of Sensory Integration
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• v.15 no.2
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• pp.80-92
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• 2017

Objective : The purpose of this study is to investigate the meaning of students' experience participating in the flipped learning based instruction in sensory integration, and to understand the demand and introspection of participants. Methods : This study used a phenomenological approach of qualitative study. The participants were 10 students in 3rd year of the occupational therapy program in K Univeristy. Data information was collected by one-to-one interview and analyzed through phenomenological research method. Results : Through the interview, 20 units of meaning, 8 central meanings, and 3 themes were drew. The information collected were analyzed into three themes; Learning Experiences in Online and Offline Courses, Request and Introspection of Learners on Flipped Learning. The result showed that online courses brought learners convenience and satisfaction with repeatable learning in every time and space the learner want. However, the learners appealed issues of communication and concentration due to the absence of face-to-face instruction by their instructor. For the offline courses, students showed interest in various practical classwork of sensory integration and changes in their attitude to actively engage in the practical classes. Conclusion : Flipped learning based instruction was effective for the sensory integration classes which require practice in terms of time securement and immersion in practice. The learners requested for adopting flipped learning based instruction to other subjects in occupational therapy curriculum, and introspected that they needed to actively engage in classes through the experience of flipped learning-based classes of sensory integration. The results of this study can be used as a basic resource when flipped learning classes are planned in occupational therapy education.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.581-584
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• 2008

Generally, durability of concrete structures under marine environment is grossly declined by detrimental ions such as chlorides, which penetrate concrete and was diffused to corrode reinforcing rod. Therefore, chloride diffusion properties in concrete are important for durability evaluation and design of concrete structure. For estimation of chloride diffusion coefficient in concrete, both evaluation methods are used for steady state and non-steady state derived from Fick's 1st and 2nd law, respectively. However, as it is very difficult to evaluate diffusion coefficient for non-steady state like service environment where concrete is actually exposed, indirect evaluation method by laboratory accelerated test is generally used. In this study, comparison of chloride diffusion behavior was investigated for fixed mix proportion and age of concrete using four accelerated test methods based on domestic and foreign standards. From test results, only relative comparison between concrete mixtures was possible using ASTM C 1202 test, and diffusion coefficient for steady state was estimated as low as 1/10 of that for non-steady state. In addition, diffusion coefficient estimated by immersion test was similar to result by NT build 492 test.

• Tuberculosis and Respiratory Diseases
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• v.42 no.4
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• pp.513-521
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• 1995

Background: Nucleolar organizer regions(NORs) are chromosomal segments encoding for ribosomal RNA and associated with argyrophilic nonhistone protein. Ribosomal RNA genes ultimately direct ribosome and protein synthesis, and it has been suggested the numbers of NORs detected in the cell may reflect nuclear and cellular activity. This study was performed to evaluate the applicability of AgNORs to the diagnosis of squamous cell carcinoma of the lung. Method: The one step silver methods(AgNORs) was used to stain NORs in the routinely processed, formalin fixed, paraffin embedded sections of 36 cases of squamous cell carcinoma of the lung obtained by surgical resection of primary tumor. In each specimen, 100 tumor cells and 100 normal cells adjacent to the tumor chosen at random were examined under an oil immersion lens at a magnification of ${\times}1000$. The mean number of AgNORs per nucleus was calculated for each specimen. Results: The mean number of AgNORs per nucleus(mAgNORs) of normal bronchial epithelium and squamous cell carcinoma of the lung was $1.74{\pm}0.25$ and $4.05{\pm}0.80$, respectively. The difference of mAgNOR between normal and tumor tissue was statistically significant(p<0.001). There was no statistical difference among tumors of different stages. The difference of mAgNOR between normal and tumor tissue was statistically significant in each TNM stage(p<0.05). Conclusion: Mean AgNOR count may be used as a useful marker for the differential diagnosis of benignancy and malignancy, and proliferative activity of the cell in squamous cell carcinoma of the lung. But there was no statistical difference in mean AgNOR count among tumors of different surgical stages. Further studies for the application of mAgNORs to the diagnosis of other histologic types and cytologic specimens of the lung cancer are needed.

• Journal of Life Science
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• v.21 no.1
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• pp.56-61
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• 2011

This study was performed to investigate effective extract conditions in fronds of the Ostrich fern (Matteuccia struthiopteris) to increase antioxidant compound contents and antioxidant capacity. Powder (1 g) of lyophilizated fronds were mixed with 3 kinds of solvents (MeOH, 80% EtOH and water). Extractions were carried out using not only immersion (room temp.), heating ($60^{\circ}C$) and stirring (200rpm) for 6 hr, but also through sonication in a 42 kHz ultrasonic bath for 15, 30 and 45 min. Extracts were filtrated and measured for contents of soluble solids (SS), total polyphenols (TP; tannic acid as a standard) and total flavonoids (TF; Naringin as a standard). Antioxidant activity was expressed as $RC_{50}$ for DPPH and ABTS radical scavenging. SS (0.317 $g{\cdot}g^{-1}$ db), TP (70.90 $mg{\cdot}g^{-1}$ db) and TF (41.53 $mg{\cdot}g^{-1}$ db) contents reached their highest levels when 30 minute sonication extraction with 80% EtOH was performed, and the highest DPPH and ABTS scavenging activity was observed in the same extraction conditions ($RC_{50}$=0.14 $mg{\cdot}ml^{-1}$ and 0.09 $mg{\cdot}ml^{-1}$, respectively). From the present investigation, it can be concluded that fronds of the ostrich fern can be used as a natural material for antioxidants, and sonication for 15-30 min with 80% EtOH is an ideal extraction method for increasing their antioxidant effects and saving extraction time.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.11-15
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• 2009

Commercial tofu was cut and re-packed in a vacuum container, an airtight container and an open tofu tray in an effort to assess the effects of vacuum containers on the shelf life of leftover tofu. The re-packed tofu were stored at $5^{\circ}C$ and $25^{\circ}C$ for the enumeration of total bacteria and coliforms. We also measured changes in color, pH, and opacity. The vacuum retarded the bacterial growth under $10^5$ CFU/mL for up to 12 days at $5^{\circ}C$. The color of the tofu was unaffected by the container type at both storage temperatures, whereas the pH and opacity of the immersion solution were altered less profoundly by storage in the vacuum container at $5^{\circ}C$. However, we noted no significant differences in bacterial growths, pH, and opacity among container types at $25^{\circ}C$. The results of this study showed that the usage of vacuum containers may be a favorable method for the preservation of tofu under refrigerated conditions.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.149-157
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• 2014

The steam generator tubes of nuclear power plants have various types of corrosion failures during the plant operation. The stress corrosion cracking which occurs on the outer surface of tube is called the secondary side stress corrosion cracking and mainly occurs in the expansion-transition area of tube. The causes are the concentration of impurities by the sludge pile-up related to the geometry of its region and the residual stress by tube expansion in the process of steam generator manufacturing. Especially the directionality and sizes of residual stresses are differed according to the tube expansion methods and the direction and the frequency of tube cracks depend on their characteristics. In bases on the plant experiences, it is notified that circumferential cracks of tubes expanded with explosive expansion method are dominantly occurred compared to those of tubes done with hydraulic expansion one. Therefore in this study, according to tube expansion methods frequencies and sizes of tube cracks with specific direction are compared by means of accelerated immersion test and also the crack morphology and the specific chemicals from water-chemistry environment are observed through the fracture surface examination.