• Mass Spectrometry Letters
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• v.9 no.4
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• pp.95-99
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• 2018

An innovative, simple, and rapid assay method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated for the simultaneous determination of eight statin drugs in human urine. A simple sample clean-up procedure using the "dilute and shoot" (DAS) approach enabled a fast and reliable analysis. The influence of the dilution factor was investigated to ensure detectability and reduce the matrix effect. Chromatographic separation was performed on a Phenomenex Kinetex C18 column ($50{\times}3.0mm$ i.d., $2.6{\mu}m$) using an elution gradient of mobile phase A composed of 0.1% acetic acid, and mobile phase B composed of acetonitrile, at a flow rate of 0.35 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using electrospray ionization in positive ion mode. The total chromatographic run time was 15 min. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy, precision, and stability. The present method was successfully applied to the analysis of Rosuvastatin in urine samples after oral administration to healthy human subjects.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.442-448
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• 2009

To evaluate the combustion mechanism of each droplet cluster downstream of the premixed spray flame, the simultaneous time-series measurements were conducted by using optical measurement system consisting of laser tomography, multi-color integrated Cassegrain receiving optics (MICRO) and phase Doppler anemometer (PDA). Furthermore, the group combustion number of droplet cluster was estimated experimentally, and the combustion mechanism of droplet cluster was examined applying the theoretical analysis. The group combustion number, $G_c$, was experimentally estimated about all droplet cluster verified by planar images, and it was classified into the internal group combustion mode and the external group combustion mode according to the theoretical analysis. It is found that there are cases in which the group combustion number estimated experimentally for droplet cluster agree or disagree with the classification by theoretical analysis. The reason of disagreement is considered due to that the group combustion number was only estimated by the geometrical arrangement of droplets in cluster, and that the actual phenomenon is three-dimensional but the measurement system is two-dimensional.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.89-92
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• 2012

Wireless Mesh Network expanded the capability of the conventional wireless networking by allowing the nodes to operate in proactive mode, reactive mode or the combination of both, the hybrid mode in the multi-hopping nature. By doing so, the links between the nodes become much more robust and reliable because of the number of paths to reach a destination node from a source node can be more than 1 and do not need to rely on the access point (AP) alone to relay the messages. As there may be many possible ways to form an end-to-end link between 2 nodes, the routing security becomes another main concern of the 802.11s protocol. Besides its reliance on the 802.11i for the security measures, 802.11s also includes some new features such as the Mesh Temporal Key (MTK) and the Simultaneous Authentication of Equals (SAE). The authentication and key management (AKM) process of 802.11s were observed in this paper.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.237-245
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• 2007

In this paper, a modified PCF (Point Coordination Function) MAC (Medium Access Control) Protocol is proposed to support the multiple direct link communication between STAs (STAtions) in infrastructure mode IEEE 802.11 wireless LANs. By the proposed MAC protocol, the direct link communication between STAs, which are located within the communication range of each other, is allowed without the use of AP (Access Point) as a relay. Moreover, when multiple direct data communication between STAs can be simultaneously performed with a sufficiently small interference, multiple simultaneous direct link communication is allowed for the efficient use of radio bandwidth. AP polls STAs to grant the transmission opportunities using the direct link communication by transmitting the polling frames to STAs. An efficient polling method for granting the transmission opportunities to STAs is proposed to reduce the number of the polling frame transmissions and enhance the PCF MAC performance.

• YAKHAK HOEJI
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• v.55 no.4
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• pp.289-294
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• 2011

Illegal addition of steroids into cosmetics, ointments or drugs have been increased and their careless usage induced detrimental effect on health. We developed simultaneous analytical method using TLC, HPLC and LC/MS for the identification of 40 corticosteroids. 34 corticosteroids were well separated in HPLC with isocratic mode and remaining 6 drugs were also separated with gradient mode. All of the 40 corticosteroids were detected in negative mode in LC/MS. Halcinonide, prednisolone, triamcinolone acetonide and methylprednisolone hemisuccinate were detected in real samples.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.85-93
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• 2007

This paper presents new LVDS I/O circuits with a high noise margin for use in highly parallel I/O environments. The proposed LVDS I/O includes transmitter and receiver parts. The transmitter circuits consist of a differential phase splitter and a output stage with common mode feedback(CMFB). The differential phase splitter generates a pair of differential signals which have a balanced duty cycle and $180^{\circ}$ phase difference over a wide supply voltage variation due to SSO(simultaneous switching output) noises. The CMFB output stage produces the required constant output current and maintains the required VCM(common mode voltage) within ${\pm}$0.1V tolerance without external circuits in a SSO environment. The proposed receiver circuits in this paper utilizes a three-stage structure(single-ended differential amp., common source amp., output stage) to accurately receive high-speed signals. The receiver part employs a very wide common mode input range differential amplifier(VCDA). As a result, the receiver improves the immunities for the common mode noise and for the supply voltage difference, represented by Vgdp, between the transmitter and receiver sides. Also, the receiver produces a rail-to-rail, full swing output voltage with a balanced duty cycle(50% ${\pm}$ 3%) without external circuits in a SSO environment, which enables correct data recovery. The proposed LVDS I/O circuits have been designed and simulated with 0.18um TSMC library using H-SPICE.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.149-168
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• 2015

In cognitive radio networks (CRNs), hybrid overlay and underlay sharing transmission mode is an effective technique for improving the efficiency of radio spectrum. Unlike existing works in the literature, where only one secondary user (SU) uses overlay and underlay modes, the different transmission modes should be allocated to different SUs, according to their different quality of services (QoS), to achieve the maximal efficiency of radio spectrum. However, hybrid sharing mode allocation for heterogeneous services is still a challenge in CRNs. In this paper, we propose a new resource allocation method for hybrid sharing transmission mode of overlay and underlay (HySOU), to achieve more potential resources for SUs to access the spectrum without interfering with the primary users. We formulate the HySOU resource allocation as a mixed-integer programming problem to optimize the total system throughput, satisfying heterogeneous QoS. To decrease the algorithm complexity, we divide the problem into two sub-problems: subchannel allocation and power allocation. Cutset is used to achieve the optimal subchannel allocation, and the optimal power allocation is obtained by Lagrangian dual function decomposition and subgradient algorithm. Simulation results show that the proposed algorithm further improves spectrum utilization with a simultaneous fairness guarantee, and the achieved HySOU diversity gain is a satisfactory improvement.

• Journal of Information Processing Systems
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• v.20 no.1
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• pp.105-115
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• 2024

The hybrid teaching approach of "MOOC + SPOC + Flipped Classroom" overcomes the constraints of time and space that are typically associated with traditional teaching methods, thus compensating for the shortcomings of traditional approaches. These changes in education are driven by the "Internet+" wave and the growing popularity of online teaching. The "MOOC + SPOC + Flipped Classroom" hybrid teaching mode can successfully compensate for the drawbacks of traditional teaching methods, thereby overcoming their restrictions. By defining relevant concepts, one can distill the key characteristics of the "MOOC + SPOC + Flipped Classroom" hybrid teaching mode. Formative assessment was employed to thoroughly evaluate the effectiveness of this teaching approach. By leveraging the advantages of massive open online course (MOOC), small private online course (SPOC), and flipped classroom, the "MOOC +SPOC + Flipped Classroom" teaching mode incorporates real-time student assessment through peer evaluation, computer-aided evaluation, and teacher evaluation. This mode promotes the simultaneous development of theoretical knowledge and practical skills, helping students to establish strong foundations while fostering their practical abilities. While the traditional teaching method remains fruitful, the convenience of today's network allows the teaching profession to continually evolve. The traditional teaching mode heavily relies on teachers, making it impossible to conduct lessons without them. However, the development of MOOC enables students to seek knowledge online from their preferred teachers, rather than solely relying on their assigned instructors.

• Ocean and Polar Research
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• v.27 no.2
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• pp.115-123
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• 2005

Recently, it has been observed in the East Sea that temperature increases below the thermocline, and dissolved oxygen increase in the intermediate layer but decrease below it. The layer of minimum dissolved oxygen deepens and the bottom homogeneous layer in oxygen becomes thinner. It emerges very probably that these changes are induced by the mode change of deep water formation associated with global warming. To further support this hypothesis, a one-dimensional model experiment is performed. First, a thermal profile is obtained by injecting a cold and high oxygen deep water into the bottom layer, say the bottom mode. Then, two thermal profiles are obtained from the bottom mode profile by assuming that either all the deep water introduce into the intermediate layer has been initiated, say the intermediate mode, or that only a part of the deep water has been initiated into the intermediate layer, say the intermediate-bottom mode. The results, from the intermediate-bottom mode experiment are closest to the observed results. They show quite well the tendency for oxygen to increase in the intermediate layer and the simultaneous thinning of the bottom homogeneous layer in oxygen. Therefore, it can be said that the recently observed slow variation of the thermal structure might be associated with changes in the deep water formation from the bottom mode to the intermediate-bottom mode.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.322-328
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• 2009

The advantage of simultaneous nitrification and denitrification (SND) is to reduce requirement of oxygen as well as tank volume. The fludized media was used in the oxic (aerobic) tank of Membrane-BNR to enhance the efficiency of SND. Nowadays, the interest of applying membrane to the wastewater treatment plant has been increased, which is proved by a lot of research published about the MBR. The Membrane-BNR, consisted of total 5 reactors might be called the compact process by using the fludized media and having short HRT of 6.5 hr. It could attain the further removal of not only the organics but also nutrients such as T-N and T-P. The mode A and B were identified with or without the step feed of influent. The mode A was classified with 3 modes according to the different DO concentration in the fludized media aerobic reactor, and the mode B with step feed was operated with the optimum DO condition. The step-feed was capable of improving TN removal efficiency under the domestic wastewater with the low ratio C/N. On the other hand, the efficiency of SND with the 1.0~1.5 mg/L DO in the oxic media tank was better than the one with below 1.0 mg/L, on which the nitrification did not happen enough, and with above 3.5 mg/L, on which the reduction of anoxic area in the tank happened. It means that the profitable nitrification should be performed prior to the denitrification step. The removal efficiency of nitrogen by SND was about 20% among of total denitrified nitrogen. And some organic carbon consumed could be reduced by the endogeneous denitrification.