• Journal of Biosystems Engineering
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• v.12 no.2
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• pp.44-59
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• 1987

The objectives of this study were to analyze and develop the model systems of rice post-harvest systems from drying to processing, and to develop a bulk system among them which requires minimum system cost and less operating time. The significance of this study was the development of a computer program (PPSARR). The PPSARR makes it possible to evaluate quantitatively the performance and economics of the rice post-harvest systems. The results show that the rice post-harvest bulk system requires less time and cost such as 37-60% and 46-59% of those of the sack system, respectively. Also, the former requires less manpower than the latter. For not more than 1,800 ton of rough rice production, the bulk system which is "drying & storage by IBDS-transport-milling" is recommended, and for more than 1,800 ton, the one which is "drying & storage by IBDS - transport - storing at flat storage improved - transport - processing by RPC" is recommended.

• Journal of Biosystems Engineering
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• v.25 no.4
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• pp.279-286
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• 2000

Most of the domestic cold storage rooms are inefficient for agricultural products because of temperature gradients inside the storage rooms. Temperature gradients are developed mainly by improper airflow pattern inside the storage room, which is a main cause of the spoilage of the agricultural products. There proper airflow pattern is essential to minimize these temperature gradients and the spoilage. The performance and characteristics of a cold storage room were determined as a function of airflow pattern and temperature distribution in forced circulation cold storage room. A commercial CFD(computational fluid dynamics) code was used to simulate 3-D airflow in the cold storage room. Solving the flow equations for the storage room, a standard k-$\varepsilon$ turbulent model was implemented to calculate steady state turbulent velocity distribution. The CFD prediction results were compared with temperature measurements inside the cold storage room. In case of pallet storage, Temperature gradients inside pallet storage was reduced because the contact area of cold air expanded through an alley of airflow in storage. But is case of bulk storage, the last temperature of storage considerably rose more than the initial temperature of storage. The reason was that bulk storage didn't include any alley of airflow in storage.

• Tunnel and Underground Space
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• v.33 no.2
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• pp.71-82
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• 2023

This study presents a direct measurement method for grain bulk modulus, which is important hydraulic-mechanical properties of rock, and conducts the experiment to investigate the grain bulk modulus of sandstone. In addition, the factors affecting the grain bulk modulus were investigated, comparing volumetric characteristics of rocks with different properties. As a result of the experiment, it was confirmed that the theoretically estimated bulk modulus is overestimated than the direct measured one. The possibility of the difference was analyzed, discussing the existence of non-connected pore space due to particle structure of the rock. Finally, the experimental results showed that the direct measurement suggested in this study can reliably predict the grain bulk modulus of sandstone.

• Restorative Dentistry and Endodontics
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• v.42 no.2
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• pp.118-124
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• 2017

Objectives: This study aimed to evaluate the color stability of bulk-fill and nanohybrid resin-based composites polished with 3 different, multistep, aluminum-oxide impregnated finishing and polishing disks. Materials and Methods: Disk-shaped specimens (8 mm in diameter and 4 mm in thickness) were light-cured between two glass slabs using one nanohybid bulk-fill (Tetric EvoCeram, Ivoclar Vivadent), one micro-hybrid bulk-fill (Quixfil, Dentsply), and two nanohybrid incremental-fill (Filtek Ultimate, 3M ESPE; Herculite XRV Ultra, Kerr) resin-based composites, and aged by thermocycling (between $5-55^{\circ}C$, 3,000 cycles). Then, they were divided into subgroups according to the polishing procedure as SwissFlex ($Colt\grave{e}ne/Whaledent$), Optidisc (Kerr), and Praxis TDV (TDV Dental) (n = 12 per subgroup). One surface of each specimen was left unpolished. All specimens were immersed in coffee solution at $37^{\circ}C$. The color differences (${\Delta}E$) were measured after 1 and 7 days of storage using a colorimeter based on CIE Lab system. The data were analyzed by univariate ANOVA, Mann-Whitney U test, and Friedmann tests (${\alpha}=0.05$). Results: Univariate ANOVA detected significant interactions between polishing procedure and composite resin and polishing procedure and storage time (p < 0.05). Significant color changes were detected after 1 day storage in coffee solution (p < 0.05), except Quixfil/Optidisc which was color-stable after 7 days (p > 0.05). Polishing reduced the discoloration resistance of Tetric EvoCeram/SwissFlex, Tetric EvoCeram/Praxis TDV, Quixfil-SwissFlex, and all Herculite XRV Ultra groups after 7 days storage (p < 0.05). Conclusions: Discoloration resistance of bulk-fill resin-based composites can be significantly affected by the polishing procedures.

• Agricultural and Biosystems Engineering
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• v.3 no.2
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• pp.65-72
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• 2002

Temperature is the most influential environment parameter which affects the quality change of agricultural products in cold storage. Therefore, it is essential to keep the uniform temperature distribution in the storage room. This study was performed to analyze the air movement and temperature distribution in the forced recirculating cold storage facility and to simulate optimum storage method of green groceries using 3-D CFD(three dimensional computational fluid dynamics) computer simulation which applied the standard $textsc{k}$-$\varepsilon$ turbulence model and FVM(finite volume method). The simulation was validated by the experimental results for onion storage and the simulation model was used to simulate the temperature and velocity distribution in the storage room with reference to the change of storage method such as location of storage, no stores, bulk storage, and pallet storage. In case of no stores, internal airflow was circulated without stagnation and consequently air movement and temperature distribution were uniform. In case of bulk storage, air movement was stagnated so much and temperature distribution of onion was not uniform. Furthermore, the inner temperature of onion roses more than the initial temperature of storage. In case of pallet storage, air movement and temperature distribution of onion were so uniform that the danger of quality change was decreased.

• Restorative Dentistry and Endodontics
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• v.45 no.3
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• pp.32.1-32.12
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• 2020

Objectives: To evaluate the polymerization efficiency of a matrix-modified bulk-fill composite, and compare it to a conventional composite which has a similar filler system. The degree of conversion (DC%) and monomer elution were measured over different storage periods. Additionally, fillers' content was examined. Materials and Methods: Cylindrical specimens were prepared, in bulk and incrementally, from Filtek Bulk Fill (B) and Filtek Supreme XTE (S) composites using a Teflon mold, for each test (n = 6). Using attenuated total reflection method of Fourier transformation infrared spectroscopy, DC% was measured after 24 hours, 7 days, and 30 days. Using high-performance liquid chromatography, elution of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, urethane dimethacrylate, and bisphenol-A glycidyl dimethacrylate was measured after 24 hours, 7 days and 30 days. Filler content was examined by scanning electron microscopy (SEM). Data were analyzed using 2-way mixed-model analysis of variance (α = 0.05). Results: There was no significant difference in DC% over different storage periods between B-bulk and S-incremental. Higher monomer elution was detected significantly from S than B. The elution quantity and rate varied significantly over storage periods and between different monomers. SEM images showed differences in fillers' sizes and agglomeration between both materials. Conclusions: Matrix-modified bulk-fill composites could be packed and cured in bulk with polymerization efficiency similar to conventional composites.

• Food Science and Preservation
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• v.24 no.7
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• pp.915-922
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• 2017

This study aimed in onion production by evaluating cost and labor efficiencies of onion storage methods using either a ton-bag or a wire-steel pallet. New methods using ton-bag and wire-steel pallets were developed and applied to postharvest tasks, such as harvest packaging, transportation, and storage. The storage parameters evaluated for their effect on the logistics of onion production were: working duration, working hours, and cost expenditure. The longitudinal tensile strength of the ton-bag developed in this study was 16% higher than that of the conventional ton-bag. The wire-steel pallet developed in this study had 10% more storage capacity in a low-temperature storage room, and its truck loading capacity was more than doubled compared to that of the conventional steel pallet. There was no difference in the wasting rate during bulk storage between the newly developed wire-steel pallet and the conventional steel pallet, for 500 kg of onions. However, the bulk storage of 1,000 kg of onions using the wire-steel pallet was not found to be suitable, because the wasting rate of onions stored using the wire-pallet was 3.7% higher than that of onions stored using a conventional steel pallet. The time and the total investing costs for the bulk method decreased by 50.1% and 46.1%, respectively, compared to those for conventional harvest. In the bulk storage using the wire-steel pallet, the total storage cost decreased by 28.8%. Thus, it is estimated that we could have saved 18.3 billion won if the wire-steel pallet method about 30% of the total onion production (1,298,749 M/T) in 2016.

• Proceedings of the Korean Magnestics Society Conference
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• 2012.11a
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• pp.172-172
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• 2012

A Pt-skin $Pt_3Ni$(111) surface was reported to show high catalytic activity. In this study, we investigated the magnetic properties and electronic structures of the various oriented surfaces of bulk-terminated and Pt-segregated $Pt_3Ni$ by using a first-principles calculation method. The magnetic moments of Pt and Ni are appreciably enhanced at the bulk-terminated surfaces compared to the corresponding bulk values, whereas the magnetic moment of Pt on the Pt-segregated $Pt_3Ni$(111) surface is just slightly enhanced because of the reduced number of Ni neighboring atoms. Spin-decomposed density of states shows that the dz2 orbital plays a dominant role in determining the magnetic moments of Pt atoms in the different orientations. The lowering of the d-band center energy (-2.22 eV to -2.46 eV to -2.51 eV to -2.65 eV) in the sequence of bulk-terminated (100), (110), (111), and Pt-segregated (111) may explain the observed dependence of catalytic activity on surface orientation. Our d-band center calculation suggests that an observed enhanced catalytic activity of a $Pt_3Ni$(111) surface originates from the Pt-segregation.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.189-195
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• 2006

Bragg detuning effect if, one of the serious problems if the photopolymer is used for the recording material of holography memories. And the critical reasons of that are known as the bulk refractive index change and shrinkage of recording material. However, the trials for analyzing the effect are mainly on the K-sphere and biased on the transmission hologram. So, we approached Bragg detuning effect numerically and applied the method to the transmission holograms and the reflection holograms all together. We simulated it with MATLAB. As a result, the bulk refractive index change causes+Bragg detuning effect on the transmission holograms and the reflection holograms. But the shrinkage leads to+Bragg detuning effect on the transmission hologram and-Bragg detuning effect on the reflective hologram. Compared to experimental result, the bulk refractive index change(${\fallingdotseq}4{\times}10^{-4}$) and the ratio of shrinkage to the thickness of the material(${\fallingdotseq}1.67{\times}10^{-3}$) could be matched with Bragg detuning effect on the transmission hologram and the reflection hologram.

• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.336-344
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• 2014

Purpose: In this study, the effect of milling on paddy rice stored at low temperature, the changes in grain temperature of bulk storage bags exposed at room temperature, the post-milling water content of paddy rice, the whiteness of rice, and the rate of pest incidence were investigated and data were analyzed. Methods: Changes in temperature inside the bulk storage bags kept at low temperature and grain temperature after exposure to room temperature were measured. Experiments were conducted for identifying the reasons of post-milling quality changes in paddy rice stored at low temperature. Results: It was determined that a short-term increase of water content in paddy rice was directly related to surface condensation, and that rice should be milled at least 72 h after removal from low-temperature storage, in order to completely eliminate surface condensation of paddy rice kept in bulk storage bags. It was observed that post-milling quality of rice changed, but water content was maintained at high levels for more than 18 d in rice that was milled when condensation occurred, regardless of paper or vinyl packaging. Rice whiteness rapidly decreased in rice that was milled when condensation occurred, regardless of packaging, while rice that was milled 72 h or more after removal from low temperature storage did not show any significant changes in whiteness. No pest incidence was observed up to 12 d after removal from low temperature storage, regardless of packaging. Starting at 18 d, after removal from low temperature storage, rice that was milled when condensation occurred, was affected by pests, while 24 d after removal from low temperature storage, all portions of rice were affected by pests. Conclusions: Our results suggest that changes in post-milling quality of rice could be significantly reduced by exposing paddy rice to room temperature for at least 72 h before milling, in order to allow the increase of grain temperature and prevent surface condensation.