• Korean Journal of Child Studies
• /
• 제31권2호
• /
• pp.277-290
• /
• 2010

This study reviewed elementary school teachers' opinions on the integrated curriculum in terms of the 2007 curriculum draft revision, as well as surveying their requests in regards to the 2009 curriculum draft revision. This study was conducted by means of questionnaires with 183 elementary school teachers. Most agreed that a theme-based-integrated curriculum was better than studying separate subjects, but most also argued that it takes considerable time reorganize and implement the integrated curriculum. Successful implementation also requires further teachers' training and their cooperation. The theme-based texts have already been in use from 2009 for first and second grades. Teachers prefer training courses which focus on the integration of the subjects, understanding the nature of each subject and sharing ideas and tips. Such training can assist in identifying the gaps between the curriculum plans and real classroom applications. Furthermore it can present clear guidelines to help ensure that the curriculum is organized effectively and well managed. Networks of specialized personnel or programs were also found to be very good resources both in and out of school.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2004년도 하계학술대회
• /
• pp.226-229
• /
• 2004

본 논문은 초고주파 영역에서 개방 단말 동축선을 대신해서 복소 유전율을 측정할 수 있는 MEMS 프로브와 그 응용예로 MEMS 프로브 어레이를 제안한다. MEMS 프로브는 기존의 동축선 프로브와 달리 커넥터와의 연결이 간단하여 일회용으로 프로브를 사용할 수 있다는 점에서 의료용으로 사용할 수 있는 가능성이 있다. 샘플의 유전율 분포를 구하기 위해서 기존의 센서는 반복 접촉을 요구하고 이로 인한 번거로움과 측정 오차를 줄일 목적으로 MEMS 프로브 어레이를 개발 하였다. MEMS 프로브 어레이는 RF 스위치를 사용하여 다수의 측정 포인트를 한번의 센서 접촉으로 측정할 수 있는 새로운 개념의 프로브이다. 1GHz부터 40GHz까지의 광대역에서 0.9% 식염수의 유전율을 측정하여 MEMS 프로브의 성능을 검증하였다.

• Journal of Power Electronics
• /
• 제16권5호
• /
• pp.1661-1668
• /
• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Journal of Power Electronics
• /
• 제16권6호
• /
• pp.2212-2220
• /
• 2016

Based on the conventional PID algorithm and the adaptive PID (AD-PID) algorithm, a separate sampling adaptive PID (SSA-PID) algorithm is proposed to improve the transient response of digitally controlled DC-DC converters. The SSA-PID algorithm, which can be divided into an oversampled adaptive P (AD-P) control and an adaptive ID (AD-ID) control, adopts a higher sampling frequency for AD-P control and a conventional sampling frequency for AD-ID control. In addition, it can also adaptively adjust the PID parameters (i.e. $K_p$, $K_i$ and $K_d$) based on the system state. Simulation results show that the proposed algorithm has better line transient and load transient responses than the conventional PID and AD-PID algorithms. Compared with the conventional PID and AD-PID algorithms, the experimental results based on a FPGA indicate that the recovery time of the SSA-PID algorithm is reduced by 80% and 67% separately, and that overshoot is decreased by 33% and 12% for a 700mA load step. Moreover, the SSA-PID algorithm can achieve zero overshoot during startup.

• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.840-848
• /
• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• Korean Management Science Review
• /
• 제31권4호
• /
• pp.93-106
• /
• 2014

This paper investigated customers' willingness to pay (WTP) for the integrated news platform, which is a paid digital news service provided by Korean newspapers. The integrated news platform has been widely employed and regarded as an alternative to recover dramatically decreasing sales of newspapers since N-Screen era began. This study employed a conjoint analysis to examine WTP for the integrated news platform and its attributes. According to the results, WPT for the integrated news platform was estimated as 4543.6 won, which is only 30.3% of the real price. Digitalized newspaper and premium news were found to be significant attributes explaining customers' WTP. The results of this paper implies that present marketing strategies for the integrated news platform of Korean newspapers should be reconsidered and revised.

• Polymer Science and Technology
• /
• 제23권3호
• /
• pp.296-306
• /
• 2012

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.147-148
• /
• 2006

Describe about CAN-LIN integrated network in this treatise. Describe an search their advantage about CAN communication and LIN communication protocol. Introduce CAN-LIN integrated network system and decide.

• Journal of the Korean Chemical Society
• /
• 제57권4호
• /
• pp.489-492
• /
• 2013

N-doped $TiO_2$ microcuboids were successfully prepared by a simple one-pot hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. It was found that the N-doped $TiO_2$ microcuboids enhanced absorption in the visible light region, and exhibited higher activity for photocatalytic degradation of model dyes. Based on the experimental results, a visible light induced photocatalytic mechanism was proposed for N-doped anatase $TiO_2$ microcuboids.

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.529-530
• /
• 2006

An efficient sensing scheme adoptable in DC-DC converter is described. The output voltage of the whole DC-DC converter is fed back to the input voltage of the sensor. The comparison in the sensor is accomplished by a current push-pull action. With a fixed reference, the comparator can be embodied based on (W/L) ratios. The current-mode scheme benefits the system better than a conventional voltage-mode one in terms of small area, low power consumption.