• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.266-274
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• 2005

We have designed photonic crystal based bandpass filters whose characteristics are suitable for WDM communication system. The filters consist of coupled point defect resonators in two-dimensional photonic crystal. The frequency response of coupled resonators has been analyzed by the coupling of modes in time, from which the design parameters for the coupled resonator filters have been extracted. For the appropriate choice of the design parameters, each resonator is treated as a lumped L-C resonance circuit, and from the analogy between the equivalent circuit and the standard L-C filter circuits, the design parameters are simply determined from the table for general filter circuit design. Based on the determined design parameters, a photonic crystal based filter has been designed and its performance has been calculated using the finite-difference time-domain method. The designed filter shows a pass band of 50GHz and 0.5 dB in-band ripple, which is suitable for typical WDM communication systems with 100GHz channel spacing.

• Journal of Acupuncture Research
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• v.23 no.5
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• pp.155-165
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• 2006

Objectives : This study was to examine the effect of Intradermal Acupuncture therapy at Kyeonjeong, Cheonryo and Kokji on the shoulder pain. The research was conducted with non equivalent control group non-synchronized design. Methods :　IThe subjects were the women who was suffering for shoulder pain, who are employed at two hospitals in Busan, from April to June, 2006. The 24 women were experimental group who were applied to Intradermal Acupuncture Therapy at Kyeonjeong, Cheonryo and Kokji, while the 20 women were control group who weren't applied to any treatments. The severity of shoulder pain and the extent of the subjective symptoms of shoulder pain were pre-measured. The Intradermal Acupuncture therapy was done a total of 4 times, 2 times a week over 2 weeks and from 11 a.ｍ. to 2 p.m. as an experimental treatment. As a post survey, the severity of shoulder pain, the frequency of shoulder pain and the extent of the subjective symptoms of shoulder pain were measured after one week and two weeks of experimental treatment. Research tools are Visual Analogue Scale by Cline et al. for measuring the severity of shoulder pain and the tool developed by Japan's industrial fatigue research committee of the industrial hygienics society and modified. Results : There was a significant difference(F=4.132, p=0.019) for the severity of shoulder pain on the interaction between time and group. There was a significant difference(F=11.193, p=0.000) for the extent of the subjective symptoms of shoulder pain on the interaction between time and. group. Conclusion : Based on the above results, it can be determined that Intradermal Acupuncture Therapy at Kyeonjeong, Cheonryo and Kokji can be used as the effective treatments for reducing of shoulder pam.

• Bulletin of the Society of Naval Architects of Korea
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• v.17 no.2
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• pp.11-16
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• 1980

For vibration analysis of stiffened plates the orthotropic plate analogy is commonly accepted. As to stiffened plates in contact with water, however, there is still much uncertainty in estimation of the added mass because of the lack of direct methods. The authors, considering that for added mass of plates there are many reliable data derived theoretically or experimentally available, suggest a method to estimate the added mass of a stiffened plate by combining the mass increase factor, $\beta$, of an equivalent orthotropic plate and the correction factor, $\kappa$, for the effects of stiffeners. The latter is to be derived from systematic experimental investigations. Then, the natural frequency in water, f', can be calculated from that in air, f, by the equation $f'=f/\sqrt{1+\kappa\beta}$. To investigate practical applicability of this method, a systematic experiment was carried out with five uniaxially stiffened plates. Each of them had a plate of same size, $600mm{\times}600mm{\times}3.2mm$, but stiffeners of different size in the web-depth, 41.6mm, 51.2mm or 66.8mm and of different spacing 75mm, 100mm, or 150mm. Natural frequencies were measured under simply supported-edge conditions in both air and water, and corresponding $\kappa$ values derived. In spite of wide variations of web-depth and spcae of stiffeners, the experimental results show that the diversity of $\kappa$ values is not remarkable; mean values of $\kappa$ are 1.31 with standard deviation of 0.025 for the first modes and 1.27 with that 0.077 for the second modes. Hence, the authors concluded that the above $\kappa$ values can be used generally for the cases of uniaxially stiffened plates both sides of which contact with water, and that $\kappa$ values of general use for the cases of cross-stiffened plates may also be obtainable from similar experiments.

• Journal of Korean Public Health Nursing
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• v.4 no.1
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• pp.75-82
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• 1990

This study was to examine the effects of group reminiscence on depression of the elderly and to identify the possible use of the independent nursing intervention for reminiscence. The subjects, consisting of 46 elderly residents at D-ku, in Seoul, were divided into experimental and control group. The research was done by non-equivalent control group quasi-experimental design. Data were gathered from Oct. 4th to Dec. 2nd, 1989 through interview by questionnaire and measure the degree of depression by Zung's scale. Group reminiscence, was defined as independent nursing intervention belong to cognitive intervention by nurse. The schedule and content of reminiscence were developed by investigator. Analysis of data were done by frequency, mean, t-test, and Pearsons's correlations. The results were as follows: $\cdot$ There was no significant difference between experimental and control group after pre & post group reminiscence. $\cdot$ The mean depression score was 43.4 all subjects. In addition to, the result of added analysis were as follows; $\cdot$ There was significant difference in the depression score between healthy and unhealthy group according to perception by subjects (P<05). $\cdot$ There was significant difference between above average economic status and poor status according to perception by subjects (p<.05). $\cdot$ Depression of the subjects was related to the duration of widowhood(r=.3980, p=.015). Further research needs to be done on the effects of group reminiscence as independent nursing intervention. This study needs to be replicated in different settings, studied on the assess of psychological well being for the elderly with the exception of depression and to be identified psychological chacaracteristics of the elderly.

• Journal of Korean Public Health Nursing
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• v.4 no.1
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• pp.25-35
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• 1990

This study examined the evaluation of the information effects of the teaching on knowledge and daily activities of open heart surgery patients between 2 and 6 weeks after discharge. The subject was 29 patients being taught with teaching materials at discharge as experimental group, 20 patients who received no education as control group among the patients who had undergone open heart surgery in S.N.U.H. And research method was non-equivalent control group non-synchronized quasi-experimental design. As the tool of this study, 30 items of knowledge measurement scale which was extracted among the content of teaching materials to evaluate the effect of education and 28 items of which were designed to measure the daily activities of patients with myocardial infarction for the estimation of the degree of observance in daily activities were used. For data analysis, frequency, t-test, Pearson's correlation coefficient and Cronbach's $\alpha$ were used. The result were as follows; 1. Informations given through teaching materials were effective for increasing the knowledge of the patient with open heart surgery. The knowledge of patients increased to the top level (p<0.05) in 2 weeks after discharge. In control group, the knowledge level of patients did not increase after discharge. 2. The knowledge level daily activity of the experimental group was somewat higher than that of the control group, but there was no significant difference. The score .of the experimental group was 69.66 in 6 weeks after discharge much less than the top level score 112. 3. The correlation between knowledge and daily activities was not significant, suggesting the fact that the increase of knowledge did not influence the daily activities significantly. Recommendation was suggested that; 1) Further studies might be .needed with the increasing numbers of the subjects. 2) Daily activities of the patients with open heart surgery should be investigated for long term period until they recovered normal activities.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.166-173
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• 2011

In this paper, we implemented and analyzed a wireless power transfer (WPT) system with a CSPR topology. CSPR refers to constant current source, series resonance circuit topology of a transmitting coil, parallel resonance circuit topology of a receiving coil, and pure resistive loading. The transmitting coil is coupled by a magnetic field to the receiving coil without wire. Although the electromotive force (emf) is small (about 4.5V), the voltage on load resistor is 148V, because a parallel resonance scheme was adopted for the receiving coil. The implemented WPT system is designed to be able to transfer up to 1 kW power and can operate a LED TV. Before the implementation, the EMF reduction mechanism based on the use of ferrite and a metal shield box was confirmed by an EM simulation and we found that the EMF can be suppressed dramatically by using this shield. The operating frequency of the implemented WPT system is 30.7kHz and the air gap between two coils is 150mm. The power transferred to the load resistor is 147W and the real power transfer efficiency is 66.4 %.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1110-1121
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• 2016

The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system's characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.167-173
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• 2008

In this paper, the flexible narrow bandpass filters (BPFs) with ${\lambda}$g/4 short and ${\lambda}$g/2 open stubs by microstrip line on duroid substrate are suggested. These BPFs with narrow bandwidth show flexible bandwidth with variation of the position of the stubs using the Qe (external quality factor) without changing the impedance value at microwave range. On the other hand, by replacing the series quarter-wavelength connecting lines with the equivalent T-shaped line of bandstop filter(BSF), the compact stub bandpass filter with harmonics suppression can be realized. The BPF with ${\lambda}$g/4 short stubs shows the insertion loss of 2.1 dB and the return loss of 18 dB and BPF with ${\lambda}$g/2 open stubs shows the insertion loss of 1.2 dB and the return loss of 21.9 dB at the center frequency of 5.8 GHz and the bandwidth of 10 %.

• Smart Structures and Systems
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• v.15 no.3
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• pp.665-682
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• 2015

Structural identification or St-Id is 'the parametric correlation of structural response characteristics predicted by a mathematical model with analogous characteristics derived from experimental measurements'. This paper describes a St-Id exercise on Humber Bridge that adopted a novel two-stage approach to first calibrate and then validate a mathematical model. This model was then used to predict effects of wind and temperature loads on global static deformation that would be practically impossible to observe. The first stage of the process was an ambient vibration survey in 2008 that used operational modal analysis to estimate a set of modes classified as vertical, torsional or lateral. In the more recent second stage a finite element model (FEM) was developed with an appropriate level of refinement to provide a corresponding set of modal properties. A series of manual adjustments to modal parameters such as cable tension and bearing stiffness resulted in a FEM that produced excellent correspondence for vertical and torsional modes, along with correspondence for the lower frequency lateral modes. In the third stage traffic, wind and temperature data along with deformation measurements from a sparse structural health monitoring system installed in 2011 were compared with equivalent predictions from the partially validated FEM. The match of static response between FEM and SHM data proved good enough for the FEM to be used to predict the un-measurable global deformed shape of the bridge due to vehicle and temperature effects but the FEM had limited capability to reproduce static effects of wind. In addition the FEM was used to show internal forces due to a heavy vehicle to to estimate the worst-case bearing movements under extreme combinations of wind, traffic and temperature loads. The paper shows that in this case, but with limitations, such a two-stage FEM calibration/validation process can be an effective tool for performance prognosis.

• Journal of Korean Academy of Nursing
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• v.21 no.3
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• pp.257-267
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• 1991

This study investigated the effects of nursing in formation given verbally and a booklet on the knowledge, Physical symptoms, anxiety and daily activities of patients recovering from open heart surgery from just before discharge to six weeks after discharge. The convenience sample was of patients who had undergone open heart surgery in Seoul National University Hospital. The first 25 patients who agreed to participate in the study became the control group. They did not receive the intentional information but the usual nursing care. The next 28 patients became the experimental group who received a booklet about their post-discharge care which was discussed with them by the researcher before discharge. This study used a non equivalent control group non - synchronized quasiexperimental design. The tools included a 30 item knowledge scale, a 9 item physical symptom scale, Spielberger's state anxiety scale, and a 28 item daily activity scale. The instruments were applied before discharge and at two and six weeks after discharge. For data analysis, frequency, t-test, Pearson's Correlational Coefficient and Cronbach's $\alpha$ were used. The results were as follows : 1. Information given through the booklet was effective in increasing the knowledge of patients recovering from open heart surgery. The experimental group's knowledge was higher at 2 weeks after discharge than prior to discharge (P＜0.05). 2. There was no significant difference in physical symptoms between the two groups at two and six weeks after discharge. 3. Information given through the booklet was effective in decreasing the State Anxiety two weeks after discharge (P＜0.001) but at six weeks after discharge, there was no significant difference in anxiety between the control and the experimental groups. 4. There was no significant difference in daily activity between the two groups at two and six weeks after discharge. 5. There was a negative correlation between knowledge at discharge and at 2 weeks and anxiety at 2 weeks after discharge. There was a positive correlation between knowledge at discharge and daily activity at 2 weeks after discharge. There was a negative correlation between knowledge at 2 weeks and Physical symptom at 6 weeks after discharge.