• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.100-103
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• 2004

Experiments and simulation were done to study the impact of contrast agent when CT scan was used to attenuation correction for PET images in PET/CT system. Whole body phantom was imaged with various concentration of iodine-based contrast agent using CT. Mathematical emission and transmission density map with liver were made to simulate for whole body FDG imaging. Various transmission density maps was generated with non-uniform enhancement of contrast agent, hypo-attenuating of contrast agent for tumor, different concentration of contrast agent, and so on. Attenuation correction was done with all transmission maps. In the experiments, we confirmed that attenuation coefficient was changed by concentration of contrast agent. From the simulation data, image quality of attenuation corrected images was affected by contrast agent and artifact was produced by contrast agent. These results indicated that the contrast agent should be used with a full understanding of its potential problem in PET/CT system.

• Progress in Medical Physics
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• v.21 no.1
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• pp.9-15
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• 2010

Scatter radiation considerably affects radiographic image quality by reducing image contrast and contributing to a non-uniform background. Images containing a large portion of scatter radiation may result in an incorrect diagnosis. In the past few years, many efforts have been made to reduce the effects of scatter radiation on radiographic images. The purpose of this study is to accurately measure scatter fractions and evaluate the effectiveness of beam-stop arrays. To measure scatter fraction accurately, a beam-stop array and the SFC (Scatter Fraction Calculator) program were developed. Images were obtained using the beam-stop array for both an anti-scatter technique with an anti-scatter grid and an air gap technique. The scatter fractions of the images were measured using the SFC program. Scatter fractions obtained with an anti-scatter grid were evaluated and compared to scatter fractions obtained without an anti-scatter grid. Scatter fractions were also quantitatively measured and evaluated with an air gap technique. The effectiveness of the beam-stop array was demonstrated by quantifying scatter fractions under various conditions. The results showed that a beam-stop array and the SFC program can be used to accurately measure scatter fractions in radiographic images and can be applied for both developing scatter correction methods as well as systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1185-1191
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• 2014

Gas turbine blades that have complex geometry of the cooling holes and cooling passages are usually subjected to cyclic and sustained thermal loads due to changes in the operating characteristic in combined power plants; these results in non-uniform temperature and stress distributions according to time to gas turbine blades. Those operation conditions cause creep or thermo-mechanical fatigue damage and reduce the lifetime of gas turbine blades. Thus, an accurate analysis of the stresses caused by various loading conditions is required to ensure the integrity and to ensure an accurate life assessment of the components of a gas turbine. It is well known that computational analysis such as cross-linking process including CFD, heat transfer and stress analysis is used as an alternative to demonstration test. In this paper, temperatures and stresses of gas turbine blade were calculated with fluid-structural analysis integrating fluid-thermal-solid analysis methodologies by considering actual operation conditions. Based on analysis results, additionally, the total lifetime was obtained using creep and thermo-mechanical damage model.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.1-11
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• 2003

In order to measure aperture variation dependent on normal stress and to characterize on relationship between aperture variation and hydraulic conductivity this study measured apertures of rock fractures under a high resolution confocal laser scanning microscope (CLSM) with application of five stages of uniaxial normal stresses. From this method the response of aperture can be continuously characterized on one specimen by different loads of normal stress. The results of measurements showed a rough geometry of fracture bearing non-uniform aperture. They also revealed different values of aperture variations according to the load stages on each position along a fracture due to the fracture roughness. Laboratory permeability tests were also conducted to evaluate the changes of permeability coefficients related to the aperture variations by different loads. The results of permeability tests revealed that the hydraulic conductivity was not reduced at a fixed rate with increase of normal load. Moreover, the rates of aperture variations did not match to those of hydraulic conductivity. The hydraulic conductivity calculated in this study did not follow the cubic law, representing that the parallel plate model is not suitable to express the fracture geometry corresponding to the results of aperture measurements under the CLSM.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.238-246
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if variable rate treatment (VRT) of N fertilizer, that was prescribed for site-specific management at panicle initiation stage, could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, 33kg N/ha at PIS) method. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model· equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for the calculation of the required N were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with an average of 57kg/ha that was higher than 33 kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%$ and $7.1\%$ in VRT from $14.6\%$ and $13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. In conclusion the procedure used in this paper was believed to be reliable and promising method for reducing within-field spatial variability of rice yield and protein content. However, inexpensive, reliable, and fast estimation methods of natural N supply and plant growth and nutrition status should be prepared before this method could be practically used for site-specific crop management in large-scale rice field.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.173-180
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• 2017

In this study, air sampling locations in the stack of the Advanced Fuel Science Building (AFSB) at the Korea Atomic Energy Research Institute (KAERI) were assessed according to the ANSI/HPS N13.1-1999 specification. The velocity profile, flow angle and $10{\mu}m$ aerosol particle profile at the cross-section as functions of stack height L and stack diameter D (L/D) were assessed according to the sampling location criteria using COMSOL. The criteria for the velocity profile were found to be met at 5 L/D or more for the height, and the criteria for the average flow angle were met at all locations through this assessment. The criteria for the particle profile were met at 5 L/D and 9 L/D. However, the particle profile at the cross-section of each sampling location was found to be non-uniform. In order to establish uniformity of the particle profile, a static mixer and a perimeter ring were modeled, after which the degrees of effectiveness of these components were compared. Modeling using the static mixer indicated that the sampling locations that met the criteria for the particle profile were 5-10 L/D. When modeling using the perimeter ring, the sampling locations that met the criteria for particle profile were 5 L/D and 7-10 L/D. The criteria for the velocity profile and the average flow angle were also met at the sampling locations that met the criteria for the particle profile. The methodologies used in this study can also be applied during assessments of air sampling locations when monitoring stacks at new nuclear facilities as well as existing nuclear facilities.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.51
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• pp.317-358
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• 2011

The purpose of this study aims to analyse the key differences of the sea waybill and electronic B/L in the international transport documents. Sea waybills look remarkably like ordinary bills of lading. Indeed, in two important ways, they are just like bills of lading: the front of the document will near a description of the quantity and apparent condition of the goods; and the back of the document provides evidence of the terms of the contract of carriage. They differ from bills of lading in that, far from indicating that the goods described are deliverable to the order of the shipper or of the consignee, they will make it explicit that the goods are deliverable only to the consignee. Again, different carries will do thai in a variety of ways. For example, the document may call itself non-negotiable, omitting the word order from the consignee box on the front of the document, and stating explicitly that the goods will be deliverable to the consignee or his authorised representative on proper proof of identity and authorisation. The Hague-Visby Rules and Hamburg Rules give no guidance as to any right to instruct the carrier in respect of goods while they are in transit. However, in applying Article 50 of the Rotterdam Rules, in particular when applying it in the context of seawaybills, straight bills of lading or ship's delivery orders, regard would need to be had to preserve the shipper's rights under any of those three documents even after the buyer of goods covered by them has acquired rights of its own. And, the right of control is defined at Article 1.12 of the Rotterdam Rules. The right to give instruction is further limited by the terms of Article 50.1 to three particular types of instruction in respect of the goods, relating broadly to the goods, their delivery en route, and the identity of the consignee. And, the CMI formulated the CMI Uniform Rules for Sea Waybills for voluntary incorporation into any contract of carriage covered by such a document. Recognising that neither the Hague nor the Hague-Visby Rules are applicable to sea waybills, the CMI Rules provide that a contract of carriage covered by a waybill shall be governed by whichever international or national law, if any, would have been compulsorily applicable if the contract had in fact been covered by a bill of lading or similar document of title.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.320-326
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• 2017

Multistage deep-drawing technology is used widely in the production of mobile phone battery cases to improve productivity and economy. To ensure adequate capacity and rigidity, such cases are fabricated as a rectangular cup with a high slender ratio. The multistage deep-drawing of a rectangular cup entails a high slender ratio, and the heights of the product sides may be non-uniform because of the complicated deformation mechanisms. This causes problems in product assembly that affects the surface quality of the case. This study examined a blank shape that minimizes the height variations of the product to resolve the aforementioned problems. Optimization design and analysis were performed to identify the shape that yields the least variation. The long and short sides of an oval blank were set as the design variables. The objective function was set to yield the lowest height difference, and the thickness reduction rate of the product was set to the target range. In addition, the height of the final shape was set as a constraint. The height difference was minimized successfully using the optimized design. The design process of the initial blank for all rectangular shapes can be automated in the future.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.525-532
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• 2004

N-acyl taurates are known as environmental-friendly and non-irritating to skin. In this study, the physicochemical properties of N-acyl taurates, which are amide-type anionic surfactants, were measured and also compared with sulfate-type anionic surfactants that show low biodegradability and are highly irritating to skin. The possibility of replacing the currently existing sulfate-type surfactants by N-acyl taurates was examined. Based on the experimental results, shampoos were formulated with these anionic surfactants and their stability and properties were measured. The possibility of application of amide-type surfactants to personal care cleaner was evaluated. Experimental results show that N-acyl taurates have various favorable aspects in making personal care cleanser: high viscosity, low surface tension, and low CMC values. These properties of N-acyl taurates generate nano-scale particles in emulsion, which is stable due to its high viscosity. This emulsion also has good cleaning ability with small amount of usage due to easy penetration into contaminants. Shampoo with N-methyl oleyl taurate showed high yield point and constant viscosity, and formed stable emulsion with nano- scale uniform particles. These results suggest that N-acyl taurates play an important role in making stable Interior structure in shampoo, and which improves the storage property.

• Journal of radiological science and technology
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• v.32 no.2
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• pp.161-168
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• 2009

The carotid intima-media thickness (IMT) is an early structural marker of the atherosclerotic process and is the only non-invasive test that is currently recommended by the American Heart Association for evaluation of the risk. However, use of this parameter has a limitation because it assumes uniform thickness throughout the blood vessel, whereas atherosclerosis is a focal phenomenon that is confined to intima. In fact, plaque can be found along the atherosclerotic blood vessels even though its value is unknown. The aim of this study is to analyze the carotid plaque and IMT in the stroke patients. We investigated the patients with ischemic stroke, who were admitted to the department of neurology at the Stroke Special Hospital from January to March 2008. After the carotid IMT and plaque were assessed by B-mode ultrasonography, IMT and carotid plaque to risk variables (age, sex) were analyzed. The distribution of CCA IMT was significantly different in terms of age (p = 0.004). Likewise, the distribution of carotid plaque was also significantly different in terms of age (p = 0.006). Carotid plaque was 69 and 92% in normal and abnormal CCA IMTs respectively. The results showed that the CCA IMT was closely associated with carotid plaque.