• JSTS:Journal of Semiconductor Technology and Science
• /
• v.1 no.2
• /
• pp.125-131
• /
• 2001

When the program voltage is applied to a word line, a part of the boosted channel charge in inhibited bit lines is lost due to the coupling between the string select line (SSL) and the adjacent word line. This phenomenon causes the program disturbance in the cells connected to the inhibited bit lines. This program disturbance becomes more serious, as the word line pitch is decreased. To reduce the word line coupling, the rising edge of the word-line voltage waveform was changed from a pulse step into a ramp waveform with a controlled slope. The word-line ramping circuit was composed of a timer, a decoder, a 8 b D/A converter, a comparator, and a high voltage switch pump (HVSP). The ramping voltage was generated by using a stepping waveform. The rising time and the stepping number of the word-line voltage for programming were set to $\mutextrm{m}-$ and 8, respectively,. The ramping circuit was used in a 512Mb NAND flash memory fabricated with a $0.15-\mutextrm{m}$ CMOS technology, reducing the SSL coupling voltage from 1.4V into a value below 0.4V.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.11
• /
• pp.1924-1932
• /
• 2016

Mycophenolic acid (MPA) is an antibiotic produced by Penicillium brevicompactum. MPA has antifungal, antineoplastic, and immunosuppressive functions, among others. ${\beta}-Hydroxy-{\beta}-methylglutaryl-CoA$ (HMG-CoA) lyase is a key enzyme in the bypass metabolic pathway. The inhibitory activity of HMG-CoA lyase increases the MPA biosynthetic flux by reducing the generation of by-products. In this study, we cloned the P. brevicompactum HMG-CoA lyase gene using the thermal asymmetric interlaced polymerase chain reaction and gene walking technology. Agrobacterium tumefaciens-mediated transformation (ATMT) was used to insert a mutated HMG-CoA lyase gene into P. brevicompactum. Successful insertion of the HMG-CoA lyase gene was confirmed by hygromycin screening, PCR, Southern blot analysis, and enzyme content assay. The maximum MPA production by transformants was 2.94 g/l. This was 71% higher than wild-type ATCC 16024. Our results demonstrate that ATMT may be an alternative practical genetic tool for directional transformation of P. brevicompactum.

• Journal of the Microelectronics and Packaging Society
• /
• v.7 no.3
• /
• pp.7-11
• /
• 2000

The low-voltage driven $SrTiO_3$ceramic varistor device was fabricated from $SrTiO_3$ powders prepared by co-precipitation method with $CuO-SiO_2$additives. Compare with conventional process, this process has advantages such as the reduction of the sintering temperature of $SrTiO_3$ ceramics by 100-$150^{\circ}C$ and the simplification of processing procedure. The non-linear coefficient value ($\alpha$) of the varistor showed 8.47 when it was sintered at $1350^{\circ}C$ for 2 h with 5 wt% additives in reducing atmosphere of 5% $H_2/N_2$ mixed gas. The low-voltage driven $SrTiO_3$ceramic varistor was obtained which has a breakdown voltage as low as 7 V.

• Macromolecular Research
• /
• v.11 no.1
• /
• pp.47-52
• /
• 2003

The objective of this study was to develop a polymeric drug delivery system for camptothecin (CPT), capable of improving its therapeutic index and reducing its side effects. A monomeric conjugate, 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidoethanoylcamptothecin in (ETECPT) between CPT and 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidoethanoic acid was synthesized. Its homo-and copolymer with acrylic acid (AA) were prepared by photopolymerization using 2,2-dimethoxy-2-phenylacetophenone (DMP) as a photoinitiator. The monomer and its polymers were characterized by IR, $^1$H- and $^{13}$ C-NMR spectra. The ETECPT content in poly(ETECPT-co-AA) obtained by elemental analysis was 82 wt%. The number-average molecular weights of the polymers determined by gel permeation chromatography were as follows: M$_{n}$ = 11,400 for poly(ETECPT), M$_{n}$ = 17,900 for poly(ETECPT-co-AA). The $IC_{50}$/ values of ETECPT and its polymers against cancer cells were much larger than that of CPT. Our results from the in vivo antitumor activity indicated that all polymers show high antitumor activity than CPT at a dose of 100 mg/kg./kg.

• Journal of the Korean institute of surface engineering
• /
• v.26 no.4
• /
• pp.192-202
• /
• 1993

The characteristics of the high-performance ceramic coatings fabricated on the optimum processings con-ditions for the atmospheric plasma spraying are evaluated by various material tests and analyses. The opti-mum processing parameters for the plasma spraying are determined by using the two-level orthogonal arrays of fractional factorial testing method as a statistical approach. Material tests for the coating specimens are carried out to evaluate microstructure, hardness, adhesion strength, and deposition efficiency. The properties of Al2O3-13%TiO2 coating are discussed with regard to the effective processings parameters. The decarburization effects of WC-12%Co coating is examined by XRD analysis in terms of the arc power and the secondary gas species. The hardness of Al2O2-13%TiO2 coating is increased with the arc power and shows the maximum value at around 40 lpm of Ar gas flowrate, which appears to be the most critical parame-ter on the deposition efficiency. For reducing the decarburization of WC-12%Co coating, the injection of inert He gas instead of reactive H2 gas as a secondary gas is more effective than the dropping of arc power to lessen the plasma enthalpy.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.613-616
• /
• 2008

Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the source of material such as fly ash and blast slag, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of CO$_2$ gas. In this study, we investigated the influence of the workability and compressive strength of mortar on water reducing agent, alkaline activator and curing method in oder to develop cementless blast slag based alkali-activated mortar. In view of the results, we found out that the flowability of mortar was lowered as increasing to mole concentration of NaOH, but not large the loss of flowability to 9M NaOH, most of water reducing agent was not effect. The compressive strength was improved as increasing to mole concentration of NaOH, was the most effect in 9M NaOH. The curing temperature and curing conditions on compressive strength of blast slag based alkali-activated mortar didn't influence.

• Journal of Nutrition and Health
• /
• v.29 no.2
• /
• pp.232-241
• /
• 1996

This study was designed to compare the effect of different dietary fats on plasma lipids, the degree of lipid peroxidation and the activity of antioxidant enzymes in RBC and liver rats treated with or wighout 1, 2-dimethylhydrazing (DMH). Male Sprague Dawley rats, at 7 weeks-old, were divided into control and DMH-treated grous, and each group was again subdivided into four were perilla oil (PO), blend fat (BF) containing ten different kinds of dietary oil, beef tallow (BT), corn oil (CO). At the same time, each rat was injected intramusculary with saline(for control) or DMH twice a week for 6 weeks to give total dose of 180 mg/kg body weight. Compared with BT feeding, BF reduced plasma total choesterol level and PO and Co reduced plasma TG levels (p<0.05). DMH injection decreased plasma cholesterol in all dietary groups. However, PO decreased tocopherol levels and increased TBARS levels in RBC compared to BT. The degree of hemolysis in PO group was higher than that of BT group (p<0.05 only in control group. Fatty acid composition of hepatic microsome was reflected by dietary fatty acid profile. The peroxidizability index and TBARS level in hepatic micorsome were significantly increased but tocopherol level was lowered in PO group compared to BT group. Activites of superoxide dismutase and glutathione peroxidase in RBC and hepatic cytosol were not influenced y dietary fats and DMH treatment(p<0.05). Overall, perilla oil rich in $\omega$3 $\alpha$-linolenic acid could be a very important dietary source in reducing plasma lipids and blend fat was also good dietary oil mixture in reducing plasma cholesterol. However, the degree of lipid peroxidation was greater in tissue by perilla oil feeding and it is very difficult to use only perilla oil as oil source for meal preparation, so that it could be suggested to use more perilla oil and fish to give an equal effect of blend fat in order to reduce the risk factors against cardiovascular disease.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.2
• /
• pp.207-218
• /
• 2017

Improving fuel consumption, particularly that of commercial vehicles, has become a global concern. The reduction in logistics cost has been a key issue in efforts to improve fuel economy and efficiency of transportation equipment. Typical technologies for reducing reduce fuel usage include air resistance reduction technologies, tire rolling resistance technologies, and idle technologies among others. Air resistance technology is a highly effective method that can be easily applied in a short period. As with air resistance technology, several devices involving side skirt, boat tail and gap fairing have been developed based on an analytical 3-D modeling technique for reducing air resistance attributed to the vehicle configuration. The devices were on a 45 feet tractor-trailer and the emission test was done using PEMS equipment. Fuel economy was evaluated by introducing several devices to reduce outer air resistance. The test was conducted by changing the experimental method of SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test. As a result, air resistance decreased by at least 15 % and fuel economy improved by at least 13 %. This study sought to reduce greenhouse gas and improve fuel economy by applying several devices to a test vehicle to lower air resistance.

• Journal of the Korean institute of surface engineering
• /
• v.55 no.2
• /
• pp.102-119
• /
• 2022

Gold plating is used as a coating of connecter in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. As increasing the demand for miniaturization of printed circuit boards and downsizing of electronic devices, several types of electroless gold plating solutions have been developed. Most of these conventional gold plating solutions contain cyanide compounds as a complexing agent. The gold film obtained from such baths usually satisfies the requirements for electronic parts mentioned above. However, cyanide bath is highly toxic and it always has some possibility to cause serious problems in working environment or other administrative aspects. The object of this investigation was to develop a cyanide-free electroless gold plating process that assures the high stability of the solution and gives the excellent solderability of the deposited film. The investigation reported herein is intended to establish plating bath composition and plating conditions for electroless gold plating, with thiomalic acid as a complexing agent. At the same time, we have investigated the solution stability against nickel ion and pull strength of solder ball. Furthermore, by examining the characteristics of the plated Au plating film, the problems of the newly developed electroless Au plating solution were improved and the applicability to various industrial fields was examined. New type electroless gold-plating bath which containing thiomalic acid as a complexing agent showing so good solution stability and film properties as cyanide bath. And this bath shows the excellent stability even if the dissolved nickel ion was added from under coated nickel film, which can be used at the neutral pH range.

• Journal of Bio-Environment Control
• /
• v.29 no.3
• /
• pp.277-284
• /
• 2020

To increase the utilization of the intelligent methodology of smart farm management, estimation modeling techniques are required to assess prior examination of crops and environment changes in realtime. A mandatory environmental factor such as CO₂ is challenging to establish a reliable estimation model in time domain accounted for indoor agricultural facilities where various correlated variables are highly coupled. Thus, this study was conducted to develop an artificial neural network for reducing time complexity by using environmental information distributed in adjacent areas from a time perspective as input and output variables as CO₂. The environmental factors in the smart farm were continuously measured using measuring devices that integrated sensors through experiments. Modeling 1 predicted by the mean data of the experiment period and modeling 2 predicted by the day-to-day data were constructed to predict the correlation of CO₂. Modeling 2 predicted by the previous day's data learning performed better than Modeling 1 predicted by the 60-day average value. Until 30 days, most of them showed a coefficient of determination between 0.70 and 0.88, and Model 2 was about 0.05 higher. However, after 30 days, the modeling coefficients of both models showed low values below 0.50. According to the modeling approach, comparing and analyzing the values of the determinants showed that data from adjacent time zones were relatively high performance at points requiring prediction rather than a fixed neural network model.