• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.3
• /
• pp.352-359
• /
• 2001

We propose the row method that is able to consider the SAR compliance test from the very beginning step of developing the mobile phone. The reason this new method is plausible is that we adopt the certified FDTD for the reliability of calculation, utilizing 1 mm high resolution model that is to model the phantom and the mobile phone almost identically to the reality. In this paper we introduce the process that will apply the proposed method in order to reduce the SAR of the mobile phone that has been problematic in satisfying the SAR compliance test. It results in dropping in the SAR that we keep the mobile phone or its antenna while we use it. Therefore here we make a claim as fellows. When we develop the new mobile phone, we should use the computer simulation combining the CAD design and radiation pattern rather than make a prototype and then use the trial and error method. Moreover the former way leads us to boost up the developing efficiency and reduce the cost.

• Journal of IKEEE
• /
• v.5 no.1 s.8
• /
• pp.67-74
• /
• 2001

In this paper, we propose a new method to improve tile processing of route recovery of the existing DSR algorithm on detection of route error. In mobile ad hoc networks, mobile nodes themselves have routing capability. Thus, a well-defined routing protocol is required for route set-up between two mobile nodes. However, the existing DSR routing protocol has problem with dropping of packets due to the recovery delay when a route error occurs. In order to alleviate tile problem, we propose an enhanced DSR protocol to reduce the route error recovery tine and evaluate the protocol through simulation. As tile result of evaluation, we found the proposed DSR protocol provided about 4 to 30 times faster route error recovery time according to the test scenario than the existing DSR protocol.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.7A
• /
• pp.711-723
• /
• 2002

A finer granular scalable (FGS) version of ISO/IEC MPEG-4 video streaming is investigated in this work with the prioritized stream delivery over loss-rate differentiated networks. Our proposed system is focused on the seamless integration of rate adaptation, prioritized packetization, and simplified differentiation for the MPEG-4 FGS video streaming. The proposed system consists of three key components: 1) rate adaptation with scalable source encoding, 2) content-aware prioritized packetization, and 3) loss-based differential forwarding. More specifically, a constant-quality rate adaptation is first achieved by optimally truncating the over-coded FGS stream based on the embedding rate-distortion (R-D) information (obtained from a piecewise linear R-D model). The rate-controlled video stream is then packetized and prioritized according to the loss impact of each packet. Prioritized packets are transmitted over the underlying network, where packets are subject to differentiated dropping and forwarding. By focusing on the end-to-end quality, we establish an effective working conditions for the proposed video streaming and the superior performance is verified by simulated MPEG-4 FGS video streaming.

• Korean Chemical Engineering Research
• /
• v.53 no.4
• /
• pp.472-477
• /
• 2015

This study presents modified microfluidic picoinjector combined Faraday moat with silver nanoparticle electrode to increase electrical efficiency and fabrication yield. We perform simple dropping procedure of silver nanoparticles near the picoinjection channel, which solve complicate fabrication process of electrode deposition onto the microfluidic picoinjector. Based on this approach, the microfluidic picoinjector can be reliably operated at 180 V while conventional Faraday moat usually have performed above 260 V. Thus, we can reduce the operation voltage and increase safety. Furthermore, the microfluidic picoinjector is able to precisely control injection volume from 7.5 pL to 27.5 pL. We believe that the microfluidic picoinjector will be useful platform for microchemical reaction, biological assay, drug screening, cell culture device, and toxicology.

• Transactions of the KSME C: Technology and Education
• /
• v.3 no.1
• /
• pp.37-44
• /
• 2015

In this paper dynamic deformation of lower hinge of refrigerator is simulated using dynamic finite element analysis while refrigerator is being dropped. The flow stress curves considering velocity dependency of hinge and lower packing material are determined through bending test and compression test at several dropping speeds. The determined material properties and flow stress from reverse engineering were used as input data for refrigerator's drop test using a dynamic finite element analysis software LS-DYNA. Additionally the result between CAE and 3D deformation measurement from real refrigerator drop test are compared and the result shows that the proposed analysis model is very useful to design lower hinge and lower packing endurable to the impulsive drop impact.

• Korean Journal of Child Studies
• /
• v.34 no.6
• /
• pp.57-75
• /
• 2013

The purpose of this study was to examine changes in the rate of occurrence of challenging behaviors in young children according to their increase in age. The study is based on the responses of teachers in child care centers(N=246). They were asked which 38 types of challenging behavior occur most among ages 2, 3, 4, or 5 in young children's classrooms. The major results of this study were as follows. First, the occurrence rates of young children's challenging behaviors were classified into 5 clusters; decreased(Cluster 1, Cluster 2, Cluster 3), maintained(Cluster 4), or increased(Cluster 5) according to increases in their respective ages. Second, the behaviors such as throwing tantrums and biting, evident in Cluster 1, decreased very rapidly from a very high occurrence rate by age 3. The classroom culture maladjustment behaviors such as running aimlessly around the classroom and shouting, apparent in Cluster 2, had decreased rapidly from a high occurrence rate by age 4. The intentional classroom disruptive behaviors such as dropping objects to create noise and the peer culture maladjustment behaviors studied in Cluster 3 decreased gradually from a rate of medium occurrence by age 5. These results revealed the discontinuity which a few young children exhibit. Third, hurting others, observed in Cluster 4 maintained a low occurrence rate from age 2 until age 5. Using inappropriate language and threatening others in Cluster 5 increased gradually from a low occurrence at 2 to a high rate of occurrence at age 5. By carefully examining the change of young children's challenging behaviors on the basis of objective data in terms of the continuity/discontinuity and increased/decreased rate of diverse challenging behaviors, we will be better able help teachers and parents to plan the instruction, prevention and intervention of young children's challenging behaviors.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.1 s.45
• /
• pp.189-197
• /
• 2007

Developed safety system which transfers danger information to rear cars for accident prevention when drivers detect a accident, a dropping or a freezing during driving on the high way. To prevent an accident, each vehicles mount OBU which is made up of a GPS unit and a transmitter-receiver and the trace of road is always renewed and saved in OBU per a regular past distance. When the driver see dangerous situation, transfer a danger pattern and a trace information by pressing button. All cars which receive information compare the received data with the original data. And then, only cars which are located at the rear in a regular distance respond and occur a warning. Performed a road test at the rate of $30{\sim}50$ kilometer a hour using two test cars which saved about 120meter's space between them were mounted OBU which had 447Mhz transceiver. As a result of the experiment, communication between test cars had no problem. Accordingly, it can use a safety driving device because driver can notice a danger situation and set themselves ready for it using this system in advance.

• Journal of the Korean Chemical Society
• /
• v.28 no.5
• /
• pp.315-322
• /
• 1984

The dependence of polarographic parameters on the pressure for the reduction of In(III), Cr(III), Cd(II), Pb(II), Mn(II), Co(II), Tl(I) in 0.1M KCl aqueous solution at the dropping mercury electrode have been discussed. In this experiment the temperature varied from $25^{\circ}C\;to\;35^{\circ}C$ and the pressure ranges from 1 atmosphere to 1,800 atmospheres. By increasing the pressure the reduction half-wave potentials of all metal ions are shifted markedly to more negative values and the diffusion currents of all metal ions become considerably larger. The slope of the linear relationship of E vs. log[$\frac{id-i)}{i}$] become much larger with increase in pressure, which indicates more irreversible reduction. The temperature coefficient observed over the range of the temperature from $25^{\circ}C\;to\;35^{\circ}C$ are not sensitive with increase in pressure.

• Journal of the Korean Solar Energy Society
• /
• v.40 no.5
• /
• pp.35-45
• /
• 2020

Photovoltaic (PV) power system prices have been steadily dropping in recent years due to their mass production and advances in relevant technology. Crystalline silicon (c-Si wafers) account for the largest share of the price of solar cells; reducing the thickness of these wafers is an essential part of increasing the price competitiveness of PV power systems. However, reducing the thickness of c-Si wafers is challenging; typically, phenomena such as bowing and cracking are encountered. While several approaches to address the bowing phenomenon of the c-Si solar cells exist, the only method to study the crack phenomenon (related to the strength of the c-Si solar cells) is the bending test method. Moreover, studies on determining the strength properties of the solar cells have focused largely on c-Si wafers, while those on the strength properties of front and rear-side electrodes and SiNx, the other components of c-Si solar cells, are scarce. In this study, we analyzed the strength characteristics of each layer of c-Si solar cells. The strength characteristics of the sawing mark direction produced during the production of c-Si wafers were also tested. Experiments were conducted using a 4bending tester for a specially manufactured c-Si solar cell. The results indicate that the back side electrode is the main component that experienced bowing, while the front electrode was the primary component regulating the strength of the c-Si solar cell.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.4C
• /
• pp.343-355
• /
• 2003

Fair bandwidth allocations at routers protect adaptive flows from non-adaptive ones and may simplify end-to end congestion control. However, traditional fair bandwidth allocation mechanisms, like Weighted Fair Queueing and Flow Random Early Drop, maintain state, manage buffera and perform packet scheduling on a per-flow basis. These mechanisms are more complex and less scalable than simple FIFO queueing when they are used in the interi or of a high-speed network. Recently, to overcome the implementation complexity problem and address the scalability and robustness, several fair bandwidth allocation mechanisms without per-flow state in the interior routers are proposed. Core-Stateless Fair Queueing and Rainbow Fair Queuing are approximates fair queueing in the core-stateless networks. In this paper, we proposed simple Layered Fair Queueing (SLFQ), another core-stateless mechanism to approximate fair bandwidth allocation without per-flow state. SLFQ use simple layered scheme for packet labeling and has simpler packet dropping algorithm than other core-stateless fair bandwidth allocation mechanisms. We presente simulations and evaluated the performance of SLFQ in comparison to other schemes. We also discussed other are as to which SLFQ is applicable.