• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.4
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• pp.39-47
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• 2005

In this paper, a novel high power micropump using active check valves in place of conventional passive check valves employed at the inlet and outlet ports is presented. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. A prototype micropump having an effective size of $17mm{\times}8mm{\times}11mm$ is fabricated. Frequency-dependent flow rate characteristics, bi-directional flow characteristics and load characteristics are experimentally investigated using a timing control method for valve closing motion. From the obtained experimental results, it is ascertained that optimal values of the phase shift compared to the voltage to drive pump chamber are $15^{\circ}$ for inlet check valve and $195^{\circ}$ for outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with an effective size of $10mm{\times}10mm{\times}10mm$ is fabricated and the basic characteristics are experimentally investigated.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.881-886
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• 2003

In spite of its simple design, structure and operating mechanism, swing check valves are one of the critical components which adversely affect the safety of the nuclear power plants if they fail to function properly. Therefore, it is important to evaluate the performance condition of the swing check valves in safety-related systems. The performance characteristics of swing check valves include opening characteristics, the minimum required flow velocity, the pressure drop at design flow, the disc stability, and the effect of the upstream disturbances. Among factors to identify the performance of a swing check valve, a method to evaluate the opening characteristics and the minimum required flow velocity, which guarantees to fully open the disc and hold the disc without motion, are presented to determine the operating region of the swing check valve, such as stable, tapping, or oscillation. Based on the determined operating region and opening characteristics, the simple methods of wear and fatigue analyses of the specific parts of the valve are also described.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.21-27
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• 2004

An isotope Ir-192, which is used in brachytherapy depends on import in whole quantities. There are a few ways for its activity. measurement using Welltype chamber or the way to rely on authentic decay table of manufacturer. In-air dosimetry using Farmer Chamber, etc. In this paper, let me introduce the way using Farmer chamber which is easier and simple. With the Farmer chamber and source calibration jig, take a measurement the activity of an isotope Ir-192 and compare the value with the value from decay table of manufacturer and check the activity of source. The result of measurement, compared the value from decay table, by ${\pm}2.1\%$. (which belongs to recommendable value for AAPM ${\pm}5\%$ as difference of error range) It is possible to use on clinical medicine. With the increase in use of brachytherapy, the increase of import is essential. And an accurate activity check of source is compulsory. For the activity check of source, it was possible to use Farmer chamber and source calibration jig without additional purchase of Well type chamber.

• Journal of Korean Library and Information Science Society
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• v.37 no.1
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• pp.305-328
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• 2006

This paper is a bibliographic analysis on printed books of $M\grave{e}ngz\check{i}$(孟子) in Choseon Dynasty. Through examination of the physical characteristics of books in many institutes and private collections, $M\grave{e}ngz\check{i}j\acute{i}zh\grave{u}d\grave{a}q\acute{a}n$(孟子集註大全)was systematically explored, which was the most frequently published $M\grave{e}ngz\check{i}$(孟子) in Choseon Dynasty. $M\grave{e}ngz\check{i}$(孟子) was published mainly in Kyungki and Kyungsang provinces, and in the period of 17C to 19C. There are two streams of $M\grave{e}ngz\check{i}j\acute{i}zh\grave{u}d\grave{a}q\acute{a}n$. One is the series of the reprinted edition of $M\acute{i}ngbon$(明本覆刻), originated from Saseookyungdaejun(四書五經大全), compiled by Hokwang(湖廣) and colleagues in $M\acute{i}ng$(明). The second is the series of Chungyuja books(丁酉字本) among movable type books of Choseon(朝鮮活字本), the contents of which being the same as the other stream. Also, $M\grave{e}ngz\check{i}d\grave{a}iw\acute{e}n$(孟予大文) and $M\grave{e}ngz\check{i}zh\grave{e}ngw\acute{e}n$(孟子正文) are frequently published.

• Computers and Concrete
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• v.22 no.2
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• pp.133-142
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• 2018

The deterioration of existing bridges has become a major problem around the world. In the paper, a new model and an associated stress checking method are proposed for concrete box girders strengthened by external prestressing. The new model called the spatial grid model can analyze all the spatial behaviors clearly by transforming the box girder into discrete orthogonal grids which are equivalent to plate elements. Then the three-layer stresses are employed as the stress checking indices to evaluate the stress state of the plate elements. The initial stress check before strengthening reveals the cracked and potential cracking areas for existing bridges, making the strengthening design more targeted and scientific; the subsequent stress check after strengthening evaluates the strengthening effect and ensures safety. A deficient bridge is selected as the practical example, verifying the accuracy and applicability of the proposed model and stress checking method. The results show that principal stresses in the middle layer of plate elements reflect the main effects of external prestressing and thus are the key stress checking indices for strengthening. Moreover, principal stresses check should be conducted in all parts of the strengthened structure not only in the webs. As for the local effects of external prestressing especially in the areas near anchorage and deviator, normal stresses check in the outer and inner layers dominates and local strengthening measures should be taken if necessary.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.3
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• pp.54-64
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• 2022

Airlines have been introducing self check-in kiosks to reduce check-in time and improve operational efficacy to increase business revenue. The domestic airlines have actively provided kiosks at airports which are expected to reduce their operating costs and enrich their passengers' travel convenience. Based on the above background, the study investigates the factors influencing intention to use the self check-in kiosks by employing the Extended Technology Acceptance Model (ETAM). The study, therefore, designed a research model by reviewing theories and studies on the relationship among information quality, innovativeness, perceived ease of use, perceived usefulness, and intention to use the kiosks. The structural equation model revealed the following. Information quality and innovativeness had a significantly positive influence on perceived ease of use and perceived usefulness; furthermore, perceived ease of use had a significantly positive influence on perceived usefulness. In addition, both perceived ease of use and perceived usefulness had a significantly positive influence on intention to use. The results indicate that the airlines should constantly develop user-friendly contents and design of the self check-in kiosks.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.329-331
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• 2013

In the most of the telecommunication industry, it is necessary to secure consistency to overcome gaps between business logics and information systems logics. We propose a model of provision check in order to secure information consistency of customer information among information systems. First of all, we understand the concept of provision check and design a proposed model for provision check. After an experiment in a business company, we analyze its experimental results and make proposals for effective and efficient provision check in the telecommunication industry.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.284-294
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• 1996

In this paper, dynamic characteristics of an AT clutch system were investigated considering the dynamics of check ball and hydraulic control valves. Dynamic model of a pressure control solenoid valve (PCSV) was obtained by Bondgraph and permeance method. Also, the clutch piston and check ball dynamics were modeled by considering the effect of centrifugal force of the oil entrapped in the clutch chamber. In order to validate the dynamic models obtained, plunger displacement of PCSV and pressure response of the clutch supply lines were compared with the available experimental data, which were in good accordance with the numerical results. Using the dynamic model of the clutch system, simulations were performed to investigate the effect of the rotational speed on the response of clutch cylinder pressure, clutch piston and check ball displacement, and oil flow rate into the cylinder and flow rate out of the check valve.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.1
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• pp.73-85
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• 2001

Electronic check schemes are more efficient than electronic coin scheme with respect to computational costs and the amount of information exchanged. In spite of these, difficulties in making a refund reusable and in representing the face value of a check have discouraged its development. In this paper, a new online electronic check system is presented, which solves the above problems. This system uses the partially blind signature to provide user anonymity and to represent the face value of a check. The partially blind signature enables us to make the format of refunds and initially withdrawn checks identical. Thus, it allows refunds to be reused to buy goods without any limitatiosn. Both initially withdrawn checks and refunds in our system guarantee untraceability as well as unlinkability. We also use a one-time secret key as the serial number of a check to increase the efficiency of payments. The presented check system also provides multiple offline shopping sessions to minimize the number of online messages handled by a bank. During the multiple offline shopping session, we use a one-way accumulator to provide non-repudiation service. We also analyze our new systems our new system\`s security, efficiency, and atomicity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.27-40
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• 2001

In an offline system, the bank does not participate in payments. As a result, it is difficult to make the refund spendable. Due to this, current offline systems do not provide spendable refunds. In these systems, a check consists of two parts: a spendable part and a refund part. A client uses the spendable part during the payment phase, and uses the refund part to get the refund for the remainder of the check. Therefore, a client cannot reuse the remaining and must always refund it. Moreover, the relationship between the spent amount and the refund amount can be used to guess which check the client used when the client refunds the remaining. To remedy these problems, we propose a new offline system which allow clients to reuse the remaining values of the check. This system provides unlinkability of the payments made by using a single check. It also provides mechanisms to detect and identify clients who perform misconduct such as double spending and over spending. The required overall computational cost to withdraw, spend and refund a check in our system is lower than using several checks in other offline systems.