• Asian-Australasian Journal of Animal Sciences
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• v.33 no.1
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• pp.157-165
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• 2020

Objective: The objective of this study was to compare the quality of dry-aged beef from cull Hanwoo cows slaughtered at 60 or 80 months old. Methods: A total of eight cull Hanwoo carcasses with a quality grade of 3 (low-grade) were selected and divided into two age groups: 63.5±2.5 months old (n = 4) and 87.8±4.5 months old (n = 4). Whole longissimus thoracis et lumborum from the 11th rib to the last lumbar vertebrae, including the back fat, was removed from the carcass at 24 h postmortem and aged for 50 days in darkness at a temperature of 2℃±1℃, a relative humidity of 85% and an air flow of 2 m/s. The sampling was performed aseptically after 0, 20, 24, 40, and 50 days of aging. Results: Regardless of the aging period, aging increased the lightness (p<0.05), redness (p<0.05) and yellowness (p<0.05) at initial blooming (90 min after slicing) and the overall acceptance (p<0.05). No further tenderization effect was found after 20 days of aging, but aging for 50 days significantly increased the lipid oxidation (p<0.05). The generation of aroma volatiles in the roast steak from aged samples was higher (p<0.05) than that of non-aged samples. No significant effect of age at slaughter was found on the color, pH, water-holding capacity, cooking loss, shear force value, bacterial counts, volatile basic nitrogen, consumer acceptance, lipid oxidation, fatty acid composition or aroma volatiles. Conclusion: The quality of dry-aged beef obtained from cull Hanwoo cows slaughtered at either 60 or 80 months old with similar quality grade was comparable and extending dry aging for more than 40 days is not recommended considering the costs and further lipid oxidation.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.137-146
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• 2002

Purpose : This paper introduces an improved classification approach which adopts a deterministic relaxation method and an agglomerative clustering technique for the classification of MRI using neural network. The proposed approach can solve the problems of convergency to local optima and computational burden caused by a large number of input patterns when a neural network is used for image classification. Materials and methods : Application of Hopfield neural network has been solving various optimization problems. However, major problem of mapping an image classification problem into a neural network is that network is opt to converge to local optima and its convergency toward the global solution with a standard stochastic relaxation spends much time. Therefore, to avoid local solutions and to achieve fast convergency toward a global optimization, we adopt MFA to a Hopfield network during the classification. MFA replaces the stochastic nature of simulated annealing method with a set of deterministic update rules that act on the average value of the variable. By minimizing averages, it is possible to converge to an equilibrium state considerably faster than standard simulated annealing method. Moreover, the proposed agglomerative clustering algorithm which determines the underlying clusters of the image provides initial input values of Hopfield neural network. Results : The proposed approach which uses agglomerative clustering and deterministic relaxation approach resolves the problem of local optimization and achieves fast convergency toward a global optimization when a neural network is used for MRI classification. Conclusion : In this paper, we introduce a new paradigm to classify MRI using clustering analysis and deterministic relaxation for neural network to improve the classification results.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.362-362
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• 2014

Atomic layer deposition (ALD) can be regarded as a special variation of the chemical vapor deposition method for reducing film thickness. ALD is based on sequential self-limiting reactions from the gas phase to produce thin films and over-layers in the nanometer scale with perfect conformality and process controllability. These characteristics make ALD an important film deposition technique for nanoelectronics. Tantalum pentoxide ($Ta_2O_5$) has a number of applications in optics and electronics due to its superior properties, such as thermal and chemical stability, high refractive index (>2.0), low absorption in near-UV to IR regions, and high-k. In particular, the dielectric constant of amorphous $Ta_2O_5$ is typically close to 25. Accordingly, $Ta_2O_5$ has been extensively studied in various electronics such as metal oxide semiconductor field-effect transistors (FET), organic FET, dynamic random access memories (RAM), resistance RAM, etc. In this experiment, the variations of chemical and interfacial state during the growth of $Ta_2O_5$ films on the Si substrate by ALD was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor $Ta(N^tBu)(dmamp)_2$ Me was used as the metal precursor, with Ar as a purging gas and $H_2O$ as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of $Ta_2O_5$ growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the $Ta^{5+}$ state, which corresponds with the stoichiometric $Ta_2O_5$, only appeared after 4.0 cycles. Additionally, tantalum silicide was not detected at the interfacial states between $Ta_2O_5$ and Si. The measured valence band offset value between $Ta_2O_5$ and the Si substrate was 3.08 eV after 2.5 cycles.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.20-20
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• 2011

The purpose of this research aims to evaluate the emergence of new business mode in the Chinese water market since the mid-2000s - Transfer-Operate-Transfer(TOT) Projects. The study pays special attention to the case of the Hefei Wangxiaoying Wastewater Treatment TOT Project, which was awarded to the consortium of Berlin Water International and its Chinese partner in late 2004. The consortium secured an exclusive operating right for 23 years on the basis of a TOT scheme and would take responsibility of all the profits and losses in the operation of the plant. The total investment for the transfer amounted to RMB 491 million(US$70 million). The price was more than 288% of the original value, RMB 170 million (US$24 million). The project can be regarded as a successful case because of the following three causes. First, the Hefei government followed a series of standardized procedures in the international bidding, which ignited best-performed international players' competition for the project. Second, the project will bring in cutting-edge operation skills and management know-how. Third, the government succeeded in raising public asset values, and thanks to this, the government is able to consider other similar projects not only in the water sector but also other sectors in public utility services. Nevertheless, Berlin Water's point of view, there are several challenges. First, the company took a risk to pay such a large amount of cash to the Hefei government. Although such premium can be recouped in the operation period of 23 years, whether or not the company would be able to recover the initial investment and realize profits is in question due to an uncertainty of socio-political circumstances in China. Second, Berlin Water should expect a steep rise of water tariffs over the contract period in order to get the investment back. Water pricing is still a sensible matter to Chinese authorities, and therefore, it is uncertain if such rise of water tariffs would be possible. Third, the TOT mode leads to creation of a large amount of cash to government officials, which might have caused corruption between those who are involved in TOT deals. Then, the final contract fee would soar, which often results in the burden of normal customers. As discussed, the TOT mode has drawn much attention of foreign investors as a new alternative to enter into the Chinese water market. But it is important to note that foreign investors should be aware of possible risks in water TOT projects, which reflects some features of the Chinese political economy landscape and social norms. The Hefei case indicates that benefits can overshadow risks in TOT projects, which will continue to attract foreign investors that are dedicated to establishing their strongholds in the Chinese water market.

• Membrane Journal
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• v.24 no.3
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• pp.201-212
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• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.493-498
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• 2000

The effects of RRA treatment on the microstructures and mechanical properties of 7050 Al alloy were investigated by differential scanning calolimetry, transmission electron microscopy, microhardness measurement and electrical conductivity. The hardness of 2nd-step aged specimen at $175^{\circ}C$ was decreased to mimimum value and increased to a peak hardness, and then re-decreased with retrogression treatment. It was found that the hardness of 2nd-step aged specimen was further increased by 3rd step aging treatment($120^{\circ}C$x24h). The initial decrease in hardness during 2nd-step aging was due to the partial dissolution of pre-existing GP zone, the major precipitation hardening phase at T6 condition. It was confirmed that the major precipitation hardening phase at 3rd-step aging was GP zone and η' phase. The electrical conductivity increased continually through 2nd-step and 3rd-step aging treatment. It was conclude that the optium 2nd-step aging condition was at $175^{\circ}C$ for 50min by considering the hardness and electrical conductivity.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.441-449
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• 1994

The two reflective channels(red and near infrared spectrum) of advanced very high resolution radiometer(AVHRR) data were used to classify primary vegetation cover types in the Korean Peninsula. From the NOAA-11 satellite data archive of 1991, 27 daytime scenes of relatively minimum cloud coverage were obtained. After the initial radiometric calibration, normalized difference vegetation index(NDVI) was calculated for each of the 27 data sets. Four or five daily NDVI data were then overlaid for each of the six months starting from February to November and the maximum value of NDVI was retained for every pixel location to make a monthly composite. The six bands of monthly NDVI composite were nearly cloud free and used for the computer classification of vegetation cover. Based on the temporal signatures of different vegetation cover types, which were generated by an unsupervised block clustering algorithm, every pixel was classified into one of the six cover type categories. The classification result was evaluated by both qualitative interpretation and quantitative comparison with existing forest statistics. Considering frequent data acquisition, low data cost and volume, and large area coverage, it is believed that AVHRR data are effective for vegetation cover type mapping at regional scale.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.12a
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• pp.3-11
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• 2004

The power loss analysis was carried out for Ni-Cu-Zn ferrite samples with different content of NiO and ZnO. The power loss, Pcv decreases monotonically wi increasing temperature and attains to a certain value at around $100\~120$ degrees Celsius. The frequency dependence of Pcv can be explained by $Pcv\~f^n$', and n is independent of the frequency, f up to 1MHz. The Pcv decreases with an increase in ZnO/NiO. The Pcv was separated to hysteresis loss, Ph and residual loss, (Pcv-Ph). The temperature characteristics and compositional dependence of Pcv can be attributed to the Ph, while (Pcv-Ph) is not affected by both temperature and ZnO/NiO. By analyzing temperature and composition dependence of Ph and initial permeability, ${\mu}^i$ following equations could be formularized. $${\mu}_i{\mu}o=I_x\;^2/(K_1+bs_ol_s)\;\;\;\;(1)$$ $Wh=13.5(I_s\;^2/{\mu}_i{\mu}_o)\;\;\;\;(2)$$ Were ${\mu}_o$ is permeability of vacuum, $I_s$ saturation magnetization, $K_1$ anisotropy constant, $S_o$ internal heterogeneous stress, $I_s$, magnetostriction constant, b unknown constant. Wh hysteresis loss per one cycle of excitation (Ph: Wh*f). Steinmetz constant of Ni-Cu-Zn ferrites, $m=1.64\~2.2$ is smaller than the one of Mn-Zn ferrites, which suggests the difference of loss mechanism between these materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.221-229
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• 1992

A series of experiments on the resuspension of deposited fine-grained sediments were carried out in a recirculating straight flume to investigate the influence of the sediment type, water content and bed shear stress (${\tau}_b$) on the resuspension characteristics of the sediments. The sediments were sampled from Youngkwang coast and Youngdo coast which are located in the western sea and southeastern sea of Korea, respectively. Critical bed shear stress (${\tau}_c$) for resuspension was deduced for each experimental series. For the same sediment, critical bed shear stress for resuspension decreased but suspension mass or rate increased with increasing water content. The resuspension of deposited fine-grained sediments depended strongly on the water content, and the sediment type characterizing the inter-particle bond strength. It has been found that critical bed shear stress for resuspension in the unidirection flow is about 4 times higher than that in the combined wave-current flow, In case of lower bed shear stress, after an initially high suspension, suspension mass approaches a constant value due to the bed hardening with increasing time, but in case of higher bed shear stress, suspension mass increased successively due to the bed softening with time. Initial suspension rate, $E={\alpha}_3({\tau}_b/{\tau}_c-1)^{\beta}$ (where ${\alpha}_3$ and ${\beta}$=empirical constants), was estimated for each experimental series, ${\alpha}_3$ and ${\beta}$ values for the same sediment increased with water content.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.706-718
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• 1997

Ceramometal crowns are common restorations in fixed prosthodontics because of their casting accuracy, the high strength properties of the metal, and the cosmetic appearance of porcelain. However, deterioration of the initial fit of the metal coping has been observed after the porcelain firing cycle. The distortion due to repeated firing makes it difficult to fit crown margin and elicits microleakage. The major causes of distortion are the residual stress that accumulate during wax-up, casting, cold work and the induced stress caused by the mismatch of porcelain-metal thermal contraction. This study examined the marginal fit changes of metal copings in relation to repeated firing and the effects of heat treatment that reduce the distortion resulted from residual stress. The marginal changes of the copings that were treated with conventional method and those treated with heat before repeated firing, were evaluated. The metal die which represented preparations of a maxillary central incisor was fabricated, and 45 wax patterns were cast with nonprecious metal alloys. The heat treatment of each group was performed as follows. Group 1(control) : Casting - Devesting - Cold work - Firing Group 2 : Casting - Heat treatment - Devesting - Cold work - Firing Group 3 : Casting - Devesting - Cold work - Reinvesting - Heat treatment - Devesting - Firing The copings were fired 3 times. After each firing, the marginal fit changes were measured with inverted metallurgical microscope at the 4 reference points located at labial, lingual, and both proximal surface. Measurements were compared, and statistically analyzed. The results were as follows ; 1. In all groups, the highest value of marginal fit changes of the copings studied were found after the first firing cycle. 2. When the distortion of each experimental group at the first firing cycle were compared, group 1 exhibited the greatest changes($20-27{\mu}m$), followed by group 2($9-13{\mu}m$), and group 3($8-10{\mu}m$). 3. The copings treated with heat before devesting(group 2) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 4. The copings treated with heat after reinvesting(group 3) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 5. No siginificant differences in marginal fit changes were found between the copings treated with heat before devesting(group 2) and the copings treated with heat after reinvesting(group 3). (p>0.01)