• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.5
• /
• pp.658-665
• /
• 2014

The neural stimulators have been employed to the visual prostheses system based on the functional electrical stimulation (FES). Due to the size limitation of the implantable device, the smaller area of the unit current driver pixel is highly desired for higher resolution current stimulation system. This paper presents a 16-channel compact current-mode neural stimulator IC with digital to analog converter (DAC) sharing scheme for artificial retinal prostheses. The individual pixel circuits in the stimulator IC share a single 6 bit DAC using the sample-and-hold scheme. The DAC sharing scheme enables the simultaneous stimulation on multiple active pixels with a single DAC while maintaining small size and low power. The layout size of the stimulator circuit with the DAC sharing scheme is reduced to be 51.98 %, compared to the conventional scheme. The stimulator IC is designed using standard $0.18{\mu}m$ 1P6M process. The chip size except the I/O cells is $437{\mu}m{\times}501{\mu}m$.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.5
• /
• pp.2637-2641
• /
• 2016

Tumor necrosis factor ($TNF-{\alpha}$), an inflammatory cytokine that plays an important role in the control of cell proliferation, differentiation, and apoptosis, has previously been used in anti-cancer therapy. However, the therapeutic applications of $TNF-{\alpha}$ are largely limited due to its general toxicity and anti-apoptotic influence. To overcome this problem, the present study focused on the effect of active constituents isolated from a medicinal plant on $TNF-{\alpha}$-induced apoptosis in human colon adenocarcinoma (HT-29) cells. Nimbolide from Azadirachta indica was evaluated for cytotoxicity by methyl tetrazolium 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay and phase contrast microscopy. Effects on apoptotic signaling proteins were investigated using Western blot analysis. Nimbolide showed cytotoxicity against HT-29 cells that was significantly different from the control group (p<0.01), a concentration of $10{\mu}M$ significantly inducing cell death (p<0.01). In combination with $TNF-{\alpha}$, nimbolide significantly enhanced-induced cell death. In apoptotic pathway, nimbolide activated c-Jun N-terminal kinase (JNK) phosphorylation, BH3 interacting-domain death agonist (Bid) and up-regulated the death receptor 5 (DR5) level. In the combination group, nimbolide markedly sensitized $TNF-{\alpha}$-induced JNK, Bid, caspase-3 activation and the up-regulation of DR5. Our findings overall indicate that nimbolide may enhance $TNF-{\alpha}$-mediated cellular proliferation inhibition through increasing cell apoptosis of HT-29 cells by up-reglation of DR5 expression via the JNK pathway.

• STI Policy Review
• /
• v.1 no.4
• /
• pp.41-61
• /
• 2010

The Korean government's support towards the establishment of leading research hubs at universities began with the initiation of the Science/ Engineering Research Center in 1990. Such efforts to provide support to research organizations have continued for some twenty years in various forms, which implies that building research hubs was critical in acquiring global leadership in research. However, the effect of such research hub nurturing policies has never been properly evaluated, apart from an assessment of their validity. Therefore, this paper analyzes how major programs to form research groups by providing assistance to joint research by researchers at universities are operated, and the characteristics of such programs through comparative analysis with other programs. There are two major focal points in the analysis: the first is the evaluation of the level of differentiation between Research Organization Support Programs (ROP) and other R&D Programs from an efficiency perspective, and the second is an examination of the extent of systematization of research organizations that exist at universities and impact of Research Organization Support Programs on the activities of participating professors from an effectiveness perspective. The result showed that the ROP were no longer only relevant for the formation and maintenance of research groups. Other R&D Programs are growing increasingly larger in scale and conducted over longer periods of time. Thus, the ROP can no longer be differentiated from other programs in research period and size of funding. An analysis on the effect of ROP demonstrated that all activities by participating professors in organizations that were the beneficiaries of group research assistance were more active compared to their counterparts in organizations that received other research support, but there was little difference in the elements of systematization. This implies that the joint research conducted at universities is not systematized and that it is still research based on individual themes but conducted jointly. In addition, it also means that the ROP is failing to effectively lead the systematization of research. In other words, today, university research organizations are not operated as independent, long-term bodies, but are more relevant as a combination of research units of individual professors.

• Steel and Composite Structures
• /
• v.21 no.5
• /
• pp.1031-1043
• /
• 2016

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis is studied in this paper. First, the element length was extracted as a fundamental variable, and the relationship between element length change and element internal force was established. By setting all pre-stresses in active cables to zero, the equation between the pre-stress deviation in the passive cables and the element length error was obtained to analyze and evaluate the error effects under different construction schemes. Afterwards, based on the probability statistics theory, the mathematical model of element length error is set up. The statistical features of the pre-stress deviation were achieved. Finally, a cable-strut tensile structure model with a diameter of 5.0 m was fabricated. The element length errors are simulated by adjusting the element length, and each member in one symmetrical unit was elongated by 3 mm to explore the error sensitivity of each type of element. The numerical analysis of error sensitivity was also carried out by the FEA model in ANSYS software, where the element length change was simulated by implementing appropriate temperature changes. The theoretical analysis and experimental results both indicated that different elements had different error sensitivities. Likewise, different construction schemes had different construction precisions, and the optimal construction scheme should be chosen for the real construction projects to achieve lower error effects, lower cost and greater convenience.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.666-671
• /
• 1999

In this work, sulfonated poly(phenylene sulfide) (SPPS) was prepared by demethylation with aqueous NaOH solution after poly[methyl[4-(phenylthio)phenyl]sulfonium trifluoromethanesulfonate](PPST) was sulfonated with fumic sulfonic acid(10% $SO_{3}-H_{2}SO_{4}$). PPST soluble in organic solvents was synthesiszed by self-condensation polymerization of methyl-(phenylthio)phenyl sulfoxide(MPPSO). SPPS showed IR bands of asymmetric O=S=O stretching at $1200cm^{-1}$ and S-O stretching at $621cm^{-1}$ from $-SO_{3}H$ group. From the result, it could be known that sulfonic acid groups were introduced to poly(phenylene sulfide). when PPST was sulfonated for 12hr at $150^{\circ}C$, 1.48 sulfonic acid groups were introduced per repeat unit. The weight average molecular weight(Mw) of PPST and SPPS determined by high temperature GPC were 118323 and 131204, respectively. The SPPS exhibited adsorption capacity of ammonia gas $9.67mmol\;NH_{3}/g$ and it was much higher than that of active carbon or silica gel.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8830-8835
• /
• 2015

As the smallest unit in the composition of any melody, motive forms the basis for melodic tunes and establishes a starting point for any creation. Among other melody composition methods, how to form a motive, change it, and refine it to develop a solo is important in playing solos, and in an impromptu jazz solo, analyzing how motive is changed and developed and using it can be a method or idea to approach a more melodic solo. This thesis consists of a thorough analysis of the kinds of developmental methods that were used to change and advance motives in three solos by Larry Grenadier, a musician who is active with creative ideas in many genres of contemporary jazz music. After such analysis, these motive development methods were applied to a rendition. Since judgment was used in the motive development methods mentioned in the introduction, elements in the methods that appeared to be motives but were impossible to analyze were excluded from the analysis, therefore making it one limitation of this study. There will be a need for future studies to overcome this limitation.

• The Korean Journal of Ecology
• /
• v.28 no.4
• /
• pp.231-235
• /
• 2005

Comparative water relations of Quercus acuta and Castanopsis cuspidata var, sieboldii were analyzed to assess their resistance to drought and low temperature stresses from early November to early December, As air temperature decreased both species showed an increased content of osmotically active solute concentration per unit of dry weight (NS/DW), leading to lower osmotic potential of both species at both full turgid state $(OP_{sat})$ and turgor loss point $(OP_{tlp})$ in December than November. No major difference in the ability to adjust osmotically was noticed between the two. This finding suggests that both species must respond adaptively under water and low temperature stresses to maintain turgor pressure in winter season. In addition to osmotic adjustment, a low bulk modulus of elasticity $(E_{max})$ shown in Castanopsis cuspidata var. sieboldii must also play an important role in turgor maintenance during winter season being apt to happen water and low temperature stresses in plants.

• Child Health Nursing Research
• /
• v.26 no.2
• /
• pp.212-221
• /
• 2020

Purpose: Nursing protocols for glucose management are well known for both healthy term newborns and high-risk newborns. However, for less risky newborns who are under only observation surveillance, hypoglycemia could be overlooked unless clinical symptoms develop. Methods: A retrospective study was performed to explore factors influencing variations in glucose levels in 91 newborns who did not require any interventions, but were under nursing surveillance, at a level II neonatal intensive care unit. Data were retrieved from electrical medical records on glucose levels, demographic characteristics, and other clinical characteristics of newborns in their first day of life from January 2016 to May 2019. Results: Glucose levels tended to stabilize within the normal range (60~80 mg/dL) as time passed during the first day of life. Cesarean section, multiple gestation, abnormal growth, and later preterm birth were associated with low glucose levels in the first 2 hours of life. Thirty-one newborns experienced a hypoglycemic episode (< 45 mg/dL) during the first 24 hours of life. Conclusion: The findings of this study support the active encouragement of early feeding within 2 hours of birth and urgent adoption of a structural protocol for glucose surveillance in newborns with potential health problems immediately after birth.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.2
• /
• pp.117-124
• /
• 2011

We demonstrate a new surface modification of high-voltage lithium cobalt oxide ($LiCoO_2$) cathode active materials for lithium-ion batteries. This approach is based on exploitation of a polarity-tuned gel polymer electrolyte (GPE) coating. Herein, two contrast polymers having different polarity are chosen: polyimide (PI) synthesized from thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid (as a polar GPE) and ethylene-vinyl acetate copolymer (EVA) containing 12 wt% vinyl acetate repeating unit (as a less polar GPE). The strong affinity of polyamic acid for $LiCoO_2$ allows the resulting PI coating layer to present a highly-continuous surface film of nanometer thickness. On the other hand, the less polar EVA coating layer is poorly deposited onto the $LiCoO_2$, resulting in a locally agglomerated morphology with relatively high thickness. Based on the characterization of GPE coating layers, their structural difference on the electrochemical performance and thermal stability of high-voltage (herein, 4.4 V) $LiCoO_2$ is thoroughly investigated. In comparison to the EVA coating layer, the PI coating layer is effective in preventing the direct exposure of $LiCoO_2$ to liquid electrolyte, which thus plays a viable role in improving the high-voltage cell performance and mitigating the interfacial exothermic reaction between the charged $LiCoO_2$ and liquid electrolytes.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.2
• /
• pp.45-53
• /
• 2009

Today, reduction of $CO_2$ exhaustion gas for global-warming prevention becomes important issues in all industrial fields. Hydraulic systems have been widely used in industrial applications due to high power density and so on. However hydraulic pump is always being operated by engine or electric motor in the conventional hydraulic system. Therefore most of the conventional hydraulic system is not efficient system. Recently, an electro-hydraulic hybrid system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. In the electro-hydraulic hybrid system, hydraulic pump is operated by electric motor only when hydraulic power is needed. Therefore the electro-hydraulic system can reduce the energy consumption drastically when compared to the conventional hydraulic systems. This paper presents a new kind of hydraulic load simulator which is composed of electro-hydraulic hybrid system. Disturbances in the real working condition make the control performance decrease or go bad. QFT controller is designed to eliminate or reduce the disturbance and improve the control performance of the electro-hydraulic load simulator. Experimental results show that the proposed controller is verified to apply for electro-hydraulic hybrid system with varied external disturbances.