• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.51-56
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• 2016

Corrugated bulkheads have many advantages compared to stiffened bulkheads, and they have thus been used for the cargo tank bulkheads of commercial vessels, such as bulk carriers, product oil carriers, and chemical tankers. Various studies have been carried out to find the optimum corrugation shape for bulk carriers, but optimum design studies for chemical tankers with bulkheads made of high-priced materials are scarce. The purpose of this study is to develop a minimum weight design method for horizontal corrugated bulkheads for a chemical tanker. An evolution strategy (ES) that searches for a reliable global optimum point was applied as an optimization technique, and the structural safety of the optimum design was verified through structural analysis using the finite element method (FEM). The results were compared with those of an existing ship, which showed a weight reduction of about 14% with equivalent structural strength.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1090-1096
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• 2010

This pitting corrosion study of welded joints of austenitic stainless steels (AISI 304L and 316L) has addressed the differentiating solidification mode using three newly introduced filler wires with a flux-cored arc welding process (FCAW). The delta ferrite (${\delta}$-ferrite) content in the welded metals increased with an increasing equivalent weight ratio of chromium/nickel ($Cr_{eq}/Ni_{eq}$). Ductility dip cracking (DDC) was observed in the welded metal containing ferrite with none of AISI 304L and 0.1% of AISI 316L. The potentiodynamic anodic polarization results revealed that the $Cr_{eq}/Ni_{eq}$ ratio in a 3.5% NaCl solution didn't much affect the pitting potential ($E_{pit}$). The AISI 316L welded metals with ${\ddot{a}}$-ferrite content of over 10% had a superior $E_{pit}$ value. Though the AISI 316L welded metal with 0.1% ferrite had larger molybdenum contents than AISI 304L specimens, it showed a similar $E_{pit}$ value because the concentration of chloride ions and the corrosion product induced severe damage near the DDC.

• Korean Journal of Remote Sensing
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• v.25 no.4
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• pp.367-374
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• 2009

Recently, new GIS applications such as gee portal and spatial data infrastructure are emerging. These are related to web computing techniques or methodologies based on web 2.0 paradigm, open API of portal, open source GIS, and international GIS standards which are independently on developing. The product of these applications can be realized in the linkage of those components. In this study, a case implementation concerning linkage with Google maps API and open source middleware named Deegree is carried out, and the results are discussed for open source uses in geo portal. Open source middleware supports various levels and types of OGC standards, so that it enables web publishing in the several web standard formats and data exchanges and interoperable uses between external database servers. Also the (unction extensions and the multi tier-based architecture within geo portal for specific purpose are possible.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.177-183
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• 2015

Incremental sheet metal forming is a manufacturing process to produce thin parts using sheet metals by a series of small incremental deformation. The process rarely needs dedicated dies and molds, thus, preparation time for the process is relatively short as to be compared to conventional metal forming. Spring back in sheet metal working is very common, which causes critical errors in dimensions. Incremental sheet metal forming is not fully investigated yet. Hence, incremental sheet metal forming frequently produces inaccurate parts. This paper proposes a method to minimize dimensional errors to improve shape accuracy of products manufactured by incremental forming. This study conducts experiments using an exclusive incremental forming machine and the material for these experiments are sheets of aluminum AL1015. This research defines a process parameter and selects a few factors for the experiments. The parameters employed in this paper are tool feed rate, tool diameter, step depth, material thickness, forming method, dies applied, and tool path method. In addition, their levels for each factor are determined. The plan of the experiments is designed using orthogonal array $L_8$ ($2^7$) which requires minimum number of experiments. Based on the measurements, dimensional errors are collected both on the tool contacted surfaces and on the non-contacted surfaces. The distances between the formed surfaces and the CAD models are scanned and recorded using a commercial software product. These collected data are statistically analyzed and ANOVAs (analysis of variances) are drawn up. From the ANOVAs, this paper concludes that the process parameters of tool diameter, forming depth, and forming method are the significant factors to reduce the errors on the tool contacted surface. On the other hand, the experimental factors of forming method and dies applied are the significant factors on the non-contacted surface. However, the negative forming method always produces better accuracy than the positive forming method.

• Journal of the Korean Solar Energy Society
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• v.28 no.4
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• pp.10-16
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• 2008

The fire resistance of thermal insulation and interior finishing materials is recently much emphasized after the fire accident at the Icheon Cold Store in January 2008. Three kinds of thermal insulation are used in buildings. They are Organic, Non-organic and cellulosic insulation. Organic insulation such as polystyrene foam board and urethane foam has high thermal resistance but it has no fire resistance. While non-organic insulation such as rockwool and glassfiber has high fire resistance, it has lower thermal resistance than organic insulation. Cellulose insulation is primarily manufactured from recycled newsprint or cardboard using shredders and fiberizers. Despite of its environmental friendliness and high thermal resistivity, its domestic use has not much increased because of the prejudice that paper can easily burn. However, the cellulose insulation as a product is about 80 wt.% cellulosic fiber and 20 wt.% chemicals, most of which are fire retardants such as boric acid and ammonium sulfate. It is required to secure its fire safety for more consumption as a building insulation in Korea. Therefore, this study investigates the fire resistance of Korean cellulose insulation according to the rate of fire retardant and finally presents the optimum rate of fire retardant in cellulose as building insulation. The fire safety test was conducted according to the ASTM C 1485-00. The test results indicate that above 18 wt% of fire retardant is necessary to secure the fire safety of cellulose insulation.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.255-259
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• 2003

In this paper, we propose an improved image encryption and decryption method using a virtual image and a joint transform correlator (JTC). The encrypted image is obtained by the Fourier transform of the product of a virtual-phase image and a random-phase image, and a Fourier transform of the decrypting key generated by the proposed phase assignment rule is used as the Fourier decrypting key. Based on the solution, the original image is reconstructed using JTC in the frequency-domain. The proposed method using a virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting by unauthorized people. And also the auto-correlation terms, which are the drawback of a JTC system, contribute to reconstructing the original image rather than to disturbing its identification. But because phase-only encryptions are sensitive to noise and scratches, phase errors can be generated in fabricating the encrypted image or the Fourier decrypting key so the errors that are responsible for degradation of the quality of the reconstructed image are analyzed and the solution is demonstrated. Computer simulations show the solution, and the proposed method is very useful for JTC architecture.

• Journal of the Korea Convergence Society
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• v.10 no.10
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• pp.91-97
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• 2019

In recent years, as feminism has emerged as a main value in Korean society, related design studies are also increasing. This research archived domestic feminist design studies to provide researchers with a genealogy of feminist design research. The research defines 'feminist design' prior to the collection of domestic feminist design studies, and examine the British-American history of the feminist design studies as an origin of the term. As a feature of the period, the number of feminist design studies surged in 1999, and since the 2000s, an average of 5.1 studies have been published annually. As a feature of each field, there were a lot of studies in fashion, visual, architecture, design science, product order in the whole studies. Feminist design researchers accumulate discourse on a clear line of studies and hope that this research will be renewed in the not too distant future.

• Clinical and Experimental Reproductive Medicine
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• v.45 no.4
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• pp.163-169
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• 2018

Objective: Zearalenone (ZEA) is a mycotoxin with potent estrogenic effects. Saffron is an herbal product that has antioxidant activities. The objective of this study was to investigate the protective role of saffron against reproductive toxicity induced by ZEA in female mice. Methods: Ninety 8-week-old female mice were randomly allocated into three treatment groups. The first group received an intraperitoneal injection of ZEA (2.5 mg/kg) on alternate days. The second group received ZEA (2.5 mg/kg) on alternate days plus oral saffron daily (50 mg/kg). The third group was treated with a vehicle of 1% dimethyl sulfoxide (DMSO) on alternate days, as a control. Ten mice were euthanized from each group at 30, 60, and 90 days of treatment. Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol ($E_2$), and progesterone (P) were assessed. The uterus and ovaries were examined for changes in size or morphology. Results: Serum levels of LH, FSH, $E_2$, and P in the female mice treated with ZEA plus saffron were significantly higher than in those treated with ZEA alone, and were not significantly different from those treated with 1% DMSO. The female mice treated with ZEA alone showed a reduction in size of the uterus and abnormal architecture of the ovaries. Conclusion: The administration of saffron to female mice resulted in a significant reduction in ZEA-induced alterations in reproductive hormone levels, the size of the uterus, and the morphology of the ovaries.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.107-107
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• 2019

Ulcerative colitis (UC) is one of inflammatory bowel disease (IBD), characterized by chronic inflammatory response and dysregulation of immune function. The severity of US has been influenced by environmental factors and food habit. The immune modulatory, anti-inflammatory and steroidal medicine have been used for the treatment of UC. However, long-term administration of those medicine is accompanied with side-effect. So, it is necessary to develop the non side-effect medicine using natural product. Prebiotics influences intestinal condition and food consumption. The heredity, immunity and environmental condition are related with occurrence of UC. In recent study, UC patients had lower level of prebiotics such as Lactobacillus and Bifidobacterium compared with healthy people. Also, previous study announced that imbalance of enteric flora aggravates the severity of UC. The effectiveness of probiotics might affect colon ability and viable bacteria also could promote the proliferation of beneficial intestinal bacteria. Prebiotics, such as herbal medicine, could lead to balance of intestinal bacteria or increase beneficial bacteria. So, proper choice of herbal medicine could control the intestinal condition. This study aimed to investigate the effect of mixture of probiotics and prebiotics (synbiotics) on dextran sulfate sodium (DSS)-induced UC in vivo. The synbiotics consist of Lactobacillus buchneri, Polymnia sonchifolia and Glycine max Merr. in this study. To evaluate the effect of synbiotics, 3% DSS was administered in BALB/c mice and synbiotics was daily administered for experimental days. The administration of synbiotics regulated colon length shortening, body weight change and disease activity index effectively. Also, extract of synbiotics upregulated survival ability of Lactobacillus buchneri in gut condition. These results suggest that mixture of probiotics and prebiotics, called as synbiotics, could influence intestinal condition also regulate the colon disease. Synbiotics might be a therapeutic agent for treatment of UC.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.29-40
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• 2018

Strength design wind loads for the wind resistance design of structures shall be evaluated by the product of wind loads calculated based on the basic wind speed with 100 years return period and the wind load factor 1.3 specified in the provisions of load combinations in Korean Building Code (KBC) 2016. It may be sure that the wind load factor 1.3 in KBC(2016) had not been determined by probabilistic method or empirical method using meteorological wind speed data in Korea. In this paper, wind load factors were evaluated by probabilistic method and empirical method. The annual maximum 10 minutes mean wind speed data at 69 meteorological stations during past 40 years from 1973 to 2012 were selected for this evaluation. From the comparison of the results of those two method, it can be found that the mean values of wind load factors calculated both probability based method and empirical based method were similar at all meteorological stations. When target level of reliability index is set up 2.5, the mean value of wind load factors for all regions should be presented about 1.35. When target level of reliability index is set up 3.0, wind load factor should be presented about 1.46. By using the relationship between importance factor(conversion factor for return period) and wind load factor, the return periods for strength design were estimated and expected wind speeds of all regions accounting for strength design were proposed. It can be found that return period to estimate wind loads for strength design should be 500 years and 800 years in according to target level of reliability index 2.5 and 3.0, respectively. The 500 years basic wind speed map for strength design was suggested and it can be used with a wind load factor 1.0.