• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.12
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• pp.1092-1098
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• 2006

The influence of the concentration of precursor solution and the number of solution coatings on the densification of the $Pb(Zr_xTi_{1-x})O_3$ (PZT) thick films was studied. PZT powder and PZT precursor solution were prepared by3 sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The composition of powder and precursor solution were PZT(70/30) and PZT(30/70), respectively. The PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 to 2.0 mol/L[M] and the number of coating was repeated from 0 to 6. The XRD patterns of all PZT thick films shelved typical perovskite polycrystalline structure. The porosity of the thick films was decreased with increasing the number of coatings and 6-time coated films with 1.5 M showed the dense microstructure and thickness of about $60{\mu}m$. The relative dielectric constant of the PZT thick film was increased with increasing the number of solution coatings and the thick films with 1.5 M, 6-time coated showed the 698. The remanent polarization the 1.5 M and 6-time coated PZT thick films was $38.3{\mu}C/cm^2$.

• Korean Journal of Clinical Pharmacy
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• v.26 no.3
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• pp.254-263
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• 2016

Objective: Written information could be helpful for senior population to adhere to complex medication therapies, but must be well prepared and empirically assessed to achieve such end. We purposed to develop a drug information leaflet for senior citizens by applying 'performance-based user-testing.' Methods: We employed a user-testing, a mixed method to figure difficulties out with patients' leaflets from the user perspective. The cycle made of test and revision can be repeated as necessary. We recruited senior citizens with age of 65 or above who were taking antihypertensive medications at the point of participating and excluded the elderly who suffered illiteracy. We firstly rectified a drug information leaflet of antihypertensive medications for the general public distributed by the Korean authority based on focus group interviews (9 participants). The revised leaflets were tested four times with 8~12 participants in each round (40 seniors in total). We targeted to develop a leaflet which more than 80% of participants understood 10 key information. Main outcomes measures were to be able to find information and be able to understand information. This study was approved by the Yeungnam University Research Ethics Committee. Results: Focus group interviews identified difficulties with small font of words, professional language, long information, and a poor structure. The leaflet was revised and in the first round questionnaire found problems with 4/10 information points; interviews disclosed all but one (normal blood pressure range) were ill-understood. The second round questionnaire and interview found fewer problems but the comprehensiveness of participants was still poor in several points. For the third and fourth rounds we revised the leaflets in the individual-targeted manner. Finally, the fourth round showed all key information found and understood by at least 80% of participants except one question about drug name. Conclusion: The drug leaflets need to be developed in a personalized mode for the seniors. There was a limit for Korean seniors to understand nonproprietary name of their drugs because they used to producers' trade names which the Korean health system predominantly works with.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2568-2580
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• 2000

This paper presents a quasi-static optimization technique for elastic structures under dynamic loads. An equivalent static load (ESL) set is defined as a static load set which generates the same displacement field as that from a dynamic load at a certain time. Multiple ESL sets calculated at every time step are employed to represent the various states of the structure under the dynamic load. They can cover every critical state that might happen at an arbitrary time. Continuous characteristics of dynamic load are simulated by multiple discontinuous ones of static loads. The calculated sets of ESLs are applied as a multiple loading condition in the optimization process. A design cycle is defined as a circulated process between an analysis domain and a design domain. Design cycles are repeated until a design converges. The analysis domain gives a loading condition necessary for the design domain. The design domain gives a new updated design to be verified by the analysis domain in the next design cycle. This iterative process is quite similar to that of the multidisciplinary optimization technique. Even though the global convergence cannot be guaranteed, the proposed technique makes it possible to optimize the structures under dynamic loads. It has also applicability, flexibility, and reliability.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.20-26
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• 2016

A wireless passive sensor network is a network which, by letting RF sources supply energy to sensor nodes, is - at least theoretically - able to live an eternal life without batteries. Due to the technological immaturity, however, a wireless passive sensor network still has many difficulties; energy scarcity, non-simultaneity of energy reception and data transmission and inefficiency in data transmission occurring at sensor nodes. Considering such practical constraints, in this paper, we propose an elementary MAC scheme supporting many sensor nodes to deliver packets to a sink node. Based on a time structure in which a charging interval for charging capacitors by using received and an acting interval for communicating with a sink node are alternately repeated, the proposed MAC scheme delivers packets to a sink node according to slotted ALOHA. In general, a contention-type scheme tends to exhibit relatively low throughput. Thus, we multilaterally evaluate the throughput performance achieved by the proposed MAC scheme using a simulation method. Simulation results show that the network-wide throughput performance can be enhanced by properly setting the length of acting interval.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.521-527
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• 2010

The Paved Track is applied to reduce maintenance cost of conventional line. The Paved Track could be used in all types of lines including earthwork, bridge, tunnel and turnout sections. In case of earthwork section, the construction joint is the most critical factor to track durability. The construction joint does not affect to the track structure directly, but the gap due to discontinuity of slabs may affect to the long-term serviceability. To evaluate this problem, the accelerated track test has been performed on the construction joint and the middle part to of the real scale Paved Track. The purpose of this test is that evaluate the vulnerability of construction joint section comparing the trends of settlement and earth pressure under repeated loads of construction joint with those of the middle slab part.

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.104-112
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• 2011

There have been few reports on the constituents and biological activity of stem bark of $Acer$ $tegmentosum$, and no phytochemical and biological studies have been reported for stem wood of $A.$ $tegmentosum$. Two flavan 3-ols (1 and 2), three phenolic acid/alcohols (3~5), and two coumarins (6 and 7) were isolated from the stem wood of $A.$ $tegmentosum$ by repeated column chromatography. The structure of isolated compounds were identified as (+)-catechin (1), (-)-epicatechin (2), $p$-hydroxybenzaldehyde (3), syringic alcohol (4), $p$-tyrosol (5), scopoletin (6), and cleomiscosin A (7) on the basis of spectroscopic evidences such as $^1H$-NMR, $^{13}C$-NMR, 2D-NMR and MS spectrum. $p$-Hydroxybenzaldehyde (3), syringic alcohol (4), scopoletin (6), and cleomiscosin A (7) have not been reported from this plant so far. (+)-Catechin (1) and (-)-epicatechin (2) showed the higher 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than butylated hydroxyanisole (BHA) used as a positive control.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.362-369
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• 2016

Recently, Last to check the security status of various medium and large bridge structures using various kinds of measurement equipment, but most of the methods are used to measure and check the displacement behavior of the bridge by a certain period. In this study, receive GPS satellite signals that can be observed in real time the whole region, a bridge to automatically measure the displacement and behavior characteristics of the structure in real-time in mm over the 24 hours, the measurement information and transmits the data to the wireless network, by making use, it was applied to the real-time monitoring system in connection with a bridge to be able to automatically notify GNSS fine displacement behavior. In fact, analysis and receives the measurement data to GNSS provided in the upper bridge of the middle and large-sized aging for this purpose, measuring USN and at the same time is converted into a three-dimensional position information of a test study was conducted to monitor the bridge displacement in real time. As a result, a vertical displacement of about 0.027~0.037m at the measurement time of day of the measurement point is that the repeated and confirmed.

• KIISE Transactions on Computing Practices
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• v.23 no.1
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• pp.1-12
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• 2017

Preventive maintenance is required for best performance of facilities in large scale industry. Ultimately, the efficiency of production is maximized by preventing the failure of facilities in advance. Typically, regular maintenance is conducted manually; however, it is hard to prevent repeated failures. Also, since measures to prevent failure depend on proactive problem-solving by the facility expert, they have limitations when the expert is absent or diagnosis error is made by an unskilled expert. Alarm system is used to aid manual facility diagnosis and early detection. However, it is not efficient in practice, since it is designed to simply collect information and is activated even with small problems. In this study, we designed and developed an automated preventive maintenance system based on expert's experience in detecting failure, determining the cause, and predicting future system failure. We also discussed the system structure designed to reuse the expert's knowledge and its applications.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.377-382
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• 2001

Mechanical behavior and electrical resistance change of CPDP (carbon particle dispersed plastic) composite consisting of epoxy resin and conductive carbon particle were investigated under monotonic loading and repeated loading-unloading. The electrical resistance almost linearly increased with increasing strain during loading and the residual electrical resistance was observed even after removing load. The value of the residual electrical resistance was dependent on the maximum strain under the applied stress. This result suggests that the estimation of maximum strain (i.e., damage) is possible by the measuring electrical resistance of composite. The behavior of electrical resistance change during and after loading was discussed on the basis of the results of microscopic deformation and fracture observation. Moreover, the relationship between the volume fraction of carbon particle and the electrical resistivity of CPDP was investigated in relation to the percolation theory. Simulation model of percolation structure was established by Monte Carlo method and the simulation result was compared to the experimental results. The electrical resistance change under applied loading was analyzed quantitatively using the percolation equation and a simple model for the critical volume fraction of carbon particle as a function of the mechanical stress. It was revealed that the prediction was in good agreement with the experimental result except in the region near the failure of material.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.395-395
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• 2000

Optimization of existing processes becomes more important than the past as environmental problems and concerns about energy savings stand out. When we can model a process mathematically, we can easily optimize it by using the model as constraints. However, modeling is very difficult for most chemical processes as they include numerous units together with their correlation and we can hardly obtain parameters. Therefore, optimization that is based on the process models is, in turn, hard to perform. Especially, f3r unknown processes, such as bioprocess or microelectronics materials process, optimization using mathematical model (first principle model) is nearly impossible, as we cannot understand the inside mechanism. Consequently, we propose a few optimization method using empirical model evolutionarily instead of mathematical model. In this method, firstly, designing experiments is executed fur removing unecessary experiments. D-optimal DOE is the most developed one among DOEs. It calculates design points so as to minimize the parameters variances of empirical model. Experiments must be performed in order to see the causation between input variables and output variables as only correlation structure can be detected in historical data. And then, using data generated by experiments, empirical model, i.e. response surface is built by PLS or MLR. Now, as process model is constructed, it is used as objective function for optimization. As the optimum point is a local one. above procedures are repeated while moving to a new experiment region fur finding the global optimum point. As a result of application to the pulp digester benchmark model, kappa number that is an indication fur impurity contents decreased to very low value, 3.0394 from 29.7091. From the result, we can see that the proposed methodology has sufficient good performance fur optimization, and is also applicable to real processes.