• Korean Journal of Food Science and Technology
• /
• v.31 no.3
• /
• pp.688-696
• /
• 1999

Changes in quality during frozen storage of meat with thermal equalized freezing and various freezing methods were investigated. When beef were frozen at freezing rate of $0.39{\sim}0.66\;cm/h$, average diameter of ice crystal were about $30{\sim}50\;{\mu}m$ and showed broken tissues or irregular cracks. At freezing velocity of $1.14{\sim}2.26\;cm/h$, ice crystals of about $10{\sim}30\;{\mu}m$ was formed mainly inside or between fiber and slight destruction of tissues was occurred. The average diameter (D) of the ice crystals were related to the characteristic freezing time $(t_c)$ by the equation: $D({\mu}m)=4.089+26.88logt_c\;(r^2=0.913)$. Beef with still-air freezing showed higher drip loss than methods of immersion and thermal equalized freezing. Also, drip loss of pork was relatively lower than beef and showed highest value to 7.39% during storage on 40 days at air-blast freezing method. No apparent change of pH during storage of frozen beef and pork by freezing methods were detected. However, least changes for sample with thermal equalized freezing was found compare to sample with still-air and air blast freezing in VBN and TBA value. The fluctuation of frozen storage temperature did not cause noticeable changes on pH and water content. However, drip loss, VBN and TBA values were increased slowly as frequency of fluctuation increased.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.3
• /
• pp.51-58
• /
• 2008

Development of a new design guide which is based on empirical-mechanistic concept for pavement design is in action. It is called AASHTO 2002 Design Guide in USA and the KPRP(Korean Pavement Research Project) in Korea. The material characteristic of hot mix asphalt is a key role in the design guide. Therefore it is urgent to get a proper materials database, especially the dynamic modulus of hot mix asphalt. In this research, dynamic modulus test, which is based on aged asphalt binder, has been carried out and proposed the predicted equation of dynamic modulus. Nine different hot mix asphalt with three different asphalt binder have been used for the dynamic modulus test. Short-term aging, which is covers the time for the production of asphalt plant, transportation, lay-down, and compaction, can be simulated at $135^{\circ}C$ with 2 hour curing. Long-term aging has been carried out for a performance period of asphalt pavement. The dynamic modulus of asphalt pavement increases with aging time. As the nominal aggregate size increases, the change of dynamic modulus is not big.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.109-112
• /
• 2008

In this study, Assessment of bond property of HSC with the rate of Blust-furnace(0, 12, and 25 percent by weight cement) and Evaluation of the relationship of the compressive strength coefficient (${\beta}$) between compressive strength with 40${\sim}$120MPa were performed. Design and Test of Bond specimens were carried out based on the ASTM C-234. Test results are follows, most specimens showed that the splitting failure in all specimens, except for B-40 series which showed that the pull-out failure. For the B-40 Series, the relation of compressive strength versus bond stress has well converged that of the proposed equation with the variation(${\beta}$=2/3) in UCB/E.E.R.C-83. The crack strength of concrete in splitting was proportioned to the compressive strength of concrete, and was the highest on the contents of blast furnace slag to 12 percent by weight of cement in each series, except for B-60 series. In the relation of admixture replacement rate versus maximum bond stress, The maximum bond stress was the highest in 12 percent by weight of cement according to less than 40MPa, and was the highest in 25 percent by weight of cement according to 80MPa.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.10
• /
• pp.987-993
• /
• 2013

Chaos communication system has characteristics of non-periodic, non-predictability, broadband signal and easy implementation. Also, chaos communication system is sensitive to the initial value, because completely another signal is generated when initial value of chaos equation is changed subtly. By these characteristics, security of chaos communication system is generally evaluated better than other digital communication systems. However, BER(Bit Error Rate) performance is worse than other digital communication systems, because transmitter and receiver of existing chaos communication system are strongly influenced by reference signal and noise. So, studies in order to improve the BER performance of chaos communication system is continuously performed. In this paper, We will propose a new CDSK (Correlation Delay Shift Keying) receiver in order to improve the BER performance. After we compare to the performance of existing receiver and proposed receiver, BER performance of proposed receiver evaluate. A novel receiver has characteristic that BER performance is better than existing receiver. However, if existing transmitter is used, existing receiver is possible to recover information bits even though BER performance is bad. Therefore, we propose a novel CDSK transmitter in order to improve the security of proposed receiver. When information bits are transmitted by using proposed transmitter, existing receiver is impossible to recover information bits, and proposed receiver is possible to recover information bits.

• Korean Chemical Engineering Research
• /
• v.49 no.6
• /
• pp.857-864
• /
• 2011

Oxy-fuel combustion with many advantages such as high combustion efficiency, low flue gas flow rate and low NOx emission has emerged as a promising CCS technology for coal combustion facilities. In this study, the effects of the direct sulfation reaction on $SO_2$ removal efficiency were evaluated in a drop tube furnace under typical oxy-fuel combustion conditions represented by high concentrations of $CO_2$ and $SO_2$ formed by gas recirculation to control furnace combustion temperature. The effects of the operating parameters including the reaction temperature, $CO_2$ concentration, $SO_2$ concentration, Ca/S ratio and humidity on $SO_2$ removal efficiency were investigated experimentally. $SO_2$ removal efficiency increased with reaction temperature up to 1,200 due to promoted calcination of limestone reagent particles. And $SO_2$ removal efficiency increased with $SO_2$ concentrations and the humidity of the bulk gas. The increase of $SO_2$ removal efficiency with $CO_2$ concentrations showed that $SO_2$ removal by limestone was mainly done by the direct sulfation reaction under oxy-fuel combustion conditions. From the impact assessment of operation parameters, it was shown that these parameters have an effects on the desulfurization reaction by the order of the Ca/S ratio > residence time > $O_2$ concentration > reaction temperature > $SO_2$ concentration > $CO_2$ concentration > water vapor. The semi-empirical model equation for to evaluate the effect of the operating parameters on the performance of in-furnace desulfurization for oxy-fuel combustion was established.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.565-570
• /
• 2010

Evapotranspriation (ET) was measured by eddy covariance method in two key ecosystems in Korea: the Seolmacheon site (a mixed forest in a complex terrain, SMK) and the Cheongmicheon site (a homogeneous rice paddy, CRK). By using the multi-year observations (SMK: Sep. 2007 - Dec. 2009, CRK: Aug. 2008 - Dec. 2009), we quantified ET and analyzed its temporal variations and control mechanisms based on the radiatively coupled combination equation. During the study period, the accumulated precipitation was about 3213 mm for the SMK site, of which about 30% (i.e., 990 mm), returned to the atmosphere as ET. At the CRK site from Jan. - Dec., 2009, the annual ET was 553 mm, which was about 40% of the annual rainfall (of 1401 mm). Both sites showed a characteristic seasonality with mid-season depression in ET that are associated with the reduced amount of available energy during the monsoon season. The decoupling parameter (${\Omega}^*$), which indicates the measure of interaction between vegetation and the atmosphere, averaged about 0.4 for the SMK site and the CRK site during the growing season. The ET from both sites was more influenced by air saturation deficit and surface conductance than available energy.

• Journal of the Korean GEO-environmental Society
• /
• v.21 no.1
• /
• pp.5-12
• /
• 2020

Vibration propagated from seismic sources has damping according to distance and amplification and reduction characteristic in different regions according to topography and geological structure. The vibration propagated from the seismic source to the bedrock is largely affected by the damping according to the separation distance, which can be simply estimated through the damping equation. However, it is important to grasp geological information by location because vibration estimation transmitted to the surface are affected by the natural period of the soil located above the bedrock. Geotechnical investigation data are needed to estimate the seismic intensity based on geological information. If there is no Vs profile, the standard penetration tests are mainly used to determine the soil parameters. The Integrated DB Center of National Geotechnical Information manages the geotechnical survey data performed on the domestic ground, and there is the standard penetration test information of 400,000 holes. In this study, the possibility of quantitation the amplification coefficient for each region was examined to calculated the physical interactive seismic intensity based on geotechnical information. At this time, the shear wave column diagram was generated from the SPT-N value and ground response analysis was performed in the target area. The site coefficients for each zone and the seismic intensity distribution for the seismic motion present a significant difference according to the analysis method and the regional setting.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.4
• /
• pp.429-438
• /
• 2011

In this study, the explicit numerical algorithm was proposed to simulate the stress erection process and ultimate-load analysis of the strarch (stressed arch) system. The strarch system is a unique and innovative structural system and member prestress comprising prefabricated plane truss frames erected through a post-tensioning stress erection procedure. The flexible bottom chord, which has sleeve and gap details, is closed by the reaction force of the prestressing tendon. The prestress imposed on the tendon will enable the strarch system to be erected. This post-tensioning process is called "stress erection process." During this process, plastic rigid-body rotation occurs to the flexible top chord due to the excessive amount of plastic strain, and the structural characteristic is unstable. In this study, the dynamic relaxation method (DRM) was adopted to calculate the nonlinear equilibrium equation of the system, and a displacement-based finite-element-formulated filament beam element was used to simulate the nonlinear behavior of the top chord sections of the strarch system. The section of the filament beam element was composed by the amount of filaments, which can be modeled by various material models. The Ramberg-Osgood and bilinear kinematic elastic plastic material models were formulated for the nonlinear material behaviors of the filaments. The numerical results that were obtained in the present study were compared with the experiment results of the stress erection and with the results of the ultimate-load analysis of the strarch unit frame. The results of the present studies are in good agreement with the previous experiment results, and the explicit DRM enabled the analysis of the post-buckling behaviors of the strarch unit frame.

• Applied Chemistry for Engineering
• /
• v.16 no.6
• /
• pp.737-741
• /
• 2005

In this study, the effect of copper content on the NO removal efficiency by Cu/MCM-41 has been investigated. MCM-41 was prepared by hydrothermal synthesis using a gel mixture of colloidal silica solution and cetyltrimethylammonium. Cu/MCM-41 was manufactured with copper content (5, 10, 20, and 40%) in Cu(II) acetylacetonate. The surface properties of MCM-41 were investigated by using pH, XRD, and FT-IR analyses. $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET's equation and Boer's t-plot methods. NO removal efficiency was confirmed by gas chromatography technique. From the experimental results, the MCM-41 was analyzed to have the surface functional groups of Si-OH and Si-O-Si and the characteristic diffraction lines (100), (110), (200), and (210) corresponding to a hexagonal arrangement structure. The copper content supported on MCM-41 appeared to increase the NO removal efficiency in spite of decreasing the specific surface areas or micropore volumes. Consequently, it was found that the copper content in Cu/MCM-41 played an important role in improving the NO removal efficiency, which was mainly attributed to the catalytic reactions.

• Journal of Digital Convergence
• /
• v.17 no.10
• /
• pp.209-221
• /
• 2019

Cooperating with a supplier with professional skills is necessary to achieve performance in the development of the innovative products. It is also important to improve development competence and share knowledge. This study empirically analyzed the effect of participant's Job Competence and Leadership Competence on Knowledge Sharing, and the effect of Purchaser Interdependence on Supplier Absorption Capacity. The purpose of the study is to confirm that Knowledge Sharing between Development Participant and Supplier contributes to Performance and to demonstrate the need for a cooperative relationship with the Supplier. A survey was conducted on the product development participants to confirm the relationship between the factors using a Structural Equation Model. As a result of the hypothesis test, the better the Individual Competence of the development participants, the better the Knowledge Sharing Activity, and then Knowledge Sharing and Interdependence are the main factor in the Absorption Capacity of the Supplier. The results of this study can contribute to improving the Supplier Absorption Capacity in the product development projects in which high technology is converged. In the future, we will study the effects of the project support activities of related departments for Performance.