• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.54-67
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• 1998

The purposes of this study were to evaluate the efficiency of dentin cutting and root-end cavity preparation, and to determine the incidence of tooth crack when root-end retrograde cavity preparation was done with. ultrasonic diamond instruments. To evaluate the efficiency of dentin cutting, ultrasonic diamond and stainless steel instruments were applied to 20 exposed bovine dentin surfaces perpendicularly or parallely at the low, and medium power settings for 1 minute ($Miniendo^{TM}$, EIE, CA, U.S.A.). The resultant cavity depth was measured. To evaluate the efficiency of cavity preparation and to investigate the incidence of tooth crack, 165 mesiobuccal, distobuccal and palatal root-ends of extracted human maxillary first molars were resected by 3 mm perpendicularly to the long axis of tooth using a slow speed diamond saw after root canal preparation and filling. Retrocavities were prepared using a ultrasonic diamond instrument or a stainless steel one of the low- or medium power settings of 2 or 6. Time consumed and the number of strokes used for the cavity preparation were measured and the incidence of tooth cracks was evaluated under a stereomicroscope. The results were as follows: Both at the low and medium power settings, and both with perpendicularly- and parallely applied tips to dentin, diamond instruments showed higher dentin cutting efficiency than stainless steel ones did (p<0.01). When tips were applied to dentin perpendicularly, both diamond instrument and stainless steel one showed higher cutting efficiency with medium power setting than with low power one (p<0.01). Both at the low- and medium power settings, both diamond instrument and stainless steel one showed higher cutting efficiency when tips were applied perpendicularly to dentin surface than applied parallely (p<0.01). At the medium power setting, the number of stroke and time consumed were less with diamond instrument than with stainless steel one (p<0.05) for the retrograde cavity preparation. At the low power setting, diamond instrument induced less tooth cracks than stainless steel one did (p<0.01).

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.219-230
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• 2020

This study was conducted to determine the optimum medium and humidification period for the strawberry (Fragaria × ananassa Duch. cv. Maehyang) cutting seedling production. The cuttings were planted in coir (CO), rockwool (RW), phenolic foam (PF), and organic foam medium (OFM) with fogging treatment in 0, 3, 6, 9, or 12 days on February, 2019. And, as the field verification examination research, cuttings were planted in CO, RW, PF, and OFM, with misting treatment in 0, 6, 9, 12, or 15 days on June, 2019. In fogging treatments, rooting and survival rates of seedlings tended to increase with longer fogging periods, and rooting and survival rates were showed significantly higher in CO medium with more than 9 days of fogging periods. In misting treatments, rooting rate was significantly higher in CO and RW medium with more than 9 days of misting periods, and survival rate was significantly higher with more than 12 days of misting periods. There was no significantly difference by growth medium and humidification period in shoot and root growth. Therefore, when considering the rooting and survival rate the CO medium with 9 days of humidification period could be beneficial for the production of the 'Maehyang' strawberry cutting seedlings.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.191-199
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• 1997

This paper develops the piece creation of Hull-structure using PC(Personal Computer) which is from CADRA of graphic program. Large-sized shipbuilding yard was carried out on the development of CNC(Computer Numerical Control) auto cutting system used in super S/W such as AUTODEF, TRIBON. But this system needs lots of expenses and high technician, and only used in large-sized shipbuilding yard, not medium-sized and small-sized shipbuilding yard. To bring up the small and medium-sized ship building yard lacking a little competitive power. Small and medium-sized shipbuilding yard need the piece creation of Hull Structure S/W which is joined with the CADRA. Therefore the piece creation of Hull-Structure S/W is developed to joined with the CADRA of graphic S/W to create the piece to be needed on as auto cutting process using PC.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.233-240
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• 2003

Recently, the world are preparing for new revolution, called as If (Information Technology), NT (Nano-Technology), and BT (Bio-Technology). NT can be applied to various fields such as semiconductor-micro technology. Ultra precision processing is required for NT in the field of mechanical engineering. Recently, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts. Therefore, in this paper, stability of ultra precision cutting unit is investigated, this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material about hinge, stability investigation is performed. In this paper, hinge shapes of micro stage in UPCU(Ultra Precision Cutting Unit) are designed as two types, where, hinge shapes are composed of round and rectangularity. Elasticity and strength are analyzed about micro stage, according to hinge shapes, by FE analysis. Micro stage in ultra precision processing machine has to keep hinge shape under cutting condition with 3-component force (cutting component, axial component, radial component) and to reduce modification against cutting force. Then we investigated its elasticity and its strength against these conditions. Material of micro stage is generally used to duralumin with small thermal deformation. But, stability of micro stage is investigated, according to elasticity and strength due to various materials, by FE analysis. Where, Used materials are composed of aluminum of low strength and cooper of medium strength and spring steel of high strength. Through this stability investigation, trial and error is reduced in design and manufacture, at the same time, we are accumulated foundation data for unit control.

• Transactions of Materials Processing
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• v.12 no.4
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• pp.358-363
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• 2003

Adiabatic shear bands have been observed in the serrated chip during high strain rate metal cutting process of medium carbon steel and titanium alloy The recent microscopic observations have shown that dynamic recrystallization occurs in the narrow adiabatic shear bands. However the conventional flow stress models such as the Zerilli-Armstrong model and the Johnson-Cook model, in general, do not predict the occurrence of dynamic recrystallization (DRX) in the shear bands and the thermal softening effects accompanied by DRX. In the present study, a strain hardening and thermal softening model is proposed to predict the adiabatic shear localized chip formation. The finite element analysis (FEA) with this proposed flow stress model shows that the temperature of the shear band during cutting process rises above 0.5Τ$_{m}$. The simulation shows that temperature rises to initiate dynamic recrystallization, dynamic recrystallization lowers the flow stress, and that adiabatic shear localized band and the serrated chip are formed. FEA is also used to predict and compare chip formations of two flow stress models in orthogonal metal cutting with AISI 1045. The predictions of the FEA agreed well with the experimental measurements.s.

• Journal of agriculture & life science
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• v.44 no.3
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• pp.23-30
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• 2010

The optimal growth condition of in vitro stem cutting of Dendrobium nobile 'Hamana Lake Dream' ${\times}$ 'No. 55' was investigated. Among various media and their concentrations, MS media had better effect on the growth of micro stem cutting than Hyponex media in all concentration levels except stem length. The activated charcoal concentration in MS media showed different effects on number of stem and root, leaf length, and fresh weight: the most effective in the range of 0.1 to 1.0 g/L and barely effective above 2.0 g/L. Addition of agar 5 g/L, sucrose at 40 g/L, and peptone at 1 g/L to MS media increased significantly stem length, leaf width, and fresh weight, internode length and number of roots, and the number of stem and leaves. On the other hand, addition of gelite with any concentration had no effect on the growth of micro stem cutting compare to that of control. The optimal temperature for growth of micro stem cutting was $28^{\circ}C$. Under the same temperature, MS medium was better than Hyponex medium for the growth of stem. In addition, sucrose at 40 g/L was the most effective on growth at $28^{\circ}C$.

• Journal of Information Technology Services
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• v.2 no.1
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• pp.1-15
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• 2003

Relentless competition and price cutting race make small/medium software business very difficult to maintain their business. Especially small software businesses are often at a disadvantage when they try to win government contracts, Due to the characteristics and importance of software industry, there is no doubt that government support for mall/medium software business is indispensible. In fact, the development of the US software industry has been strongly influenced by government policy during postware period. This paper attempts to examine the general small/medium business supporting policies currently implemented. In addition, policies in the construction industry and the US federal government are explored, in order to find appropriate roles the government should play.

• Korean Journal of Plant Resources
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• v.14 no.3
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• pp.241-246
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• 2001

Effects of cutting media on shooting and seedling characteristics were investigated to determine productivity of seedling by root cuttings of lacquer tree. Shoots developed at 3 weeks after cut planting on PV (peat moss : Vermiculite : 1 : 1), PVS (peat moss : Vermiculite : Sand : 1 : 1 : 2) and PVSC (peat moss : Vermiculite : Sand : Clay loam : 1 : 1 : 2 : 2) media, and shooting rate was the highest in PVSC medium at 10 weeks after cut planting among the treatments. Shooting numbers per scion on PH and PVC media were 2.2 but those on HSC medium was 1.3, which was not significantly different among media. PVSC medium was suitable to use the root cuttings of lacquer tree as it meets the qualifications requirements. Seedlings on PVSC medium were excellent to transplant in field as tree height, branch number, leaf number, stem diameter and leaf area were good.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.427-733
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• 2003

Adiabatic shear bands have been observed in the serrated chip during high strain rate metal cutting process of medium carbon steel and titanium alloy. The recent microscopic observations have shown that dynamic recrystallization occurs in the narrow adiabatic shear bands. However the conventional flow stress models such as the Zerilli-Armstrong model and the Johnson-Cook model, in general, do not predict the occurrence of dynamic recrystallization (DRX) in the shear bands and the thermal softening effects accompanied by DRX. In the present study, a strain hardening and thermal softening model is proposed to predict the adiabatic shear localized chip formation. The finite element analysis (FEA) with this proposed flow stress model shows that the temperature of the shear band during cutting process rises above 0.5T$\sub$m/. The simulation shows that temperature rises to initiate dynamic recrystallization, dynamic recrystallization lowers the flow stress, and that adiabatic shear localized band and the serrated chip are formed. FEA is also used to predict and compare chip formations of two flow stress models in orthogonal metal cutting with AISI 1045. The predictions of the FEA agreed well with the experimental measurements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5393-5397
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• 2011

The compressing-cutting device is used for manufacturing nano tube. the purpose of this study is to design and manufacture the compressing-cutting device witch has safety and stable performance. The most important core technology, in nano tube manufacturing, is to seam the each end of tube with appropriate pressure and to cut it off into the two part safely not to leak injected medium. Since the compressing pressure and the cutoff speed make the quality of nano tube, they are very important. This study will show the processes of design and manufacturing of compressing-cutting device.