• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.158-164
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• 2002

Some of synthetic chemicals can net as an endocrine disrupting substance in higher animals. Dioxins, DDT, PCBs and bisphenol A (BPA) are classified into endocrine disruptors and aye under a strict control in many countries. This research was designed to compare the clastogenic effects of BPA to those of ionizng radiation to establish the relaltive effectiveness of BPA by means of Tradescantia micronucleus assay. For the uptake of the BPA through the stems, groups of fresh cuttings of Tradescantia BNL 4430 weve placed in BPA solutions of 0 to 4 $\mu$M for 6 hours under continuous aeration. The other groups of the cuttings were irradiated with 0 to 0.5 Gy of gamma- rays. The frequencies of micronucleus showed a positive dose- response relationship in the range of 0 to 0.5 Gy, and a clear concentration-response relationship in the experimental range of BPA concentrations. By comparing the two experimental results, it is possible to estimate the BPA concentration and its equivalent radiation dose for a fixed value of MCN frequency. BPA of $ll.8\mu{M}$ can give rise to 53.3 MCN/100 tetrads, which is the same frequency induced by 25 cGy of gamma- rays. It is of biological importance that clinical symptoms start to develop after a whole body exposure to radiation higher than 25 cGy. The results indicate that the pollen mother cells are an excellent biological end- point for toxicity test of suspected endocrine disrupting chemicals such as bisphenol A, cotylphenol and nonylphenol.

• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.127-133
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• 2006

The major purpose of this paper to identify safety climate practices, and to find the affecting variables that influence to the difference in the level of safety climate between plants and employees. And this paper attempted to find the interventions for improving safety climate in the chemical plants. The questionnaires were developed from literature review, especially made by HSE(Health and Safety Executive) in the UK and distributed to managers and workers. The frequency analysis was applied for identifying the level of safety climate. The affecting variables(plant size, accident occurrence, accident experience, injury experience and severity, and length of employment) are tested through analysis of variance(ANOVA). The results of frequency analysis showed that both managers and workers recorded generally high level of safety climate, and the major underlying problems are inadequate H&S procedures/rules, pressure for production, and rule breaking. According to the outcomes of ANOVA, the variable 'length of employment' is the only variable which makes the level of safety climate different. From the survey of safety climate practice, this study finds the level of safety climate and three major underlying problems in safety climate factors of the responded plants, and presents two interventions for improving safety performance. Despite of these outcomes, the applied factors are remained questionable for reflecting as the best ones for identifying safety climate in the chemical industry. In addition, the bias caused by self-report exist in the reliability of the response, and the equivalent size of respondents.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.1
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• pp.1-22
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• 2012

This paper tried to verify whether the fixed fire fighting system (FFFS) that is installed in road tunnel improves evacuation performance or not. Verification was performed according to the Disaster Prevention Facilities Installation and Management Guide at Road Tunnel. Twenty seven different fire scenarios were set up for the verification and the cases that FFFS was installed were compared with the cases that FFFS was not installed. The result of the comparison showed that the average equivalent death was reduced in 26 cases out of 27 cases when water spray extinguishing system was installed. It was confirmed that the risk when was not installed was unacceptable in Hong Kong and the Netherlands. On the other hand, it was confirmed that the risk was reduced to as low as reasonably practicable (ALARP) when was installed. The cumulative frequency of average death in case with FFFS was compared against the frequency of death without FFFS: death of one or more is about 50 times less; 10 or more is about 100 times less; and the death of more than 100 is four times less. It was verified that FFFS makes improved conditions to escape from the fires in road tunnel.

• Women's Health Nursing
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• v.5 no.2
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• pp.262-277
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• 1999

The purpose of this study is to define the effects of the roles played by the Doulas : one group educated on the conventional Lamaze method known to have effects on birth pang during delivery process and the other group educated both on Lamaze and therapeutic touch. On the various factors of delivery, and thereby, provide for some basic data to develop an effective nursing intervention to relieve women of their birth pang. 136 mothers who were hospitalized in a general hospital from June 13, 1998 to May 13, 1998 to May 13, 1999 to deliver their first babies were sampled to be divided into control group, test group I and test group II and thus be subject to interviews and observations. As for the tool of study, melzack's(1975) 'pain scale', McCaffery's(1972) and Mcrachlan's(1974) 'pain expression scales' and Spielberger's (1975) 'anxiety scale' were used. The preparatory educational programs consisted of 5week Lamaze method and therapeutic touch. The research, design was quasi-experimental, non equivalent, posttest only control group design. The collected data were processed using the SPSS/PC statistics software for frequencies, means and one-way Anova as well as Tukey HSD and Scheffe test as post hoc for individual comparison. Moreover, chi-square test was used to test the differences between groups, while Pearson's correlation coefficients were analyzed to determine the correlations between anxiety and variables. The findings are as follows ; 1. The birth pain of the mothers delivering first babies scored in a subjective and objective pain scale; 1) There was a significant difference of subjective birth pain at 8~10cm opening of cervix between control group and two test groups. 2) There was no significant difference of objective birth pain as per opening of cervex among three groups in terms of sweating, facial movement, bodily posture and vocal changes. 2. There was no significant difference of trait anxiety among three groups. however, there was a significant difference of state anxiety during labor process between control group and two test groups. On the other hand, all the three groups showed a significantly lower level of anxiety during labor process than when they were carried to the hospital. 3. There was a significant difference of the time of total and first-stage labor among three groups, while there was a significant but small difference of the time elapsed from 8~10cm cervix open to the full among three groups. 4. Two test groups showed a higher frequency of natural deliveries than the control group. 5. Two test groups were subject to these drugs than the control group. In conclusion, it was found that the test group I and II showed a shorter delivery time than the control group, a higher frequency of natural delivery and a lesser use of anodyne or epidural. In particular, this study is significant to develop a nursing intervention service or a therapeutic touch which the nursing administrators can apply to their hospitals in marketing programs.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.642-653
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• 2008

This study deals with modeling of head-related transfer functions(HRTFs) using principal components analysis(PCA) in the time and frequency domains. Four PCA models based on head-related impulse responses(HRIRs), complex-valued HRTFs, augmented HRTFs, and log-magnitudes of HRTFs are investigated. The objective of this study is to compare modeling performances of the PCA models in the least-squares sense and to show the theoretical relationship between the PCA models. In terms of the number of principal components needed for modeling, the PCA model based on HRIR or augmented HRTFs showed more efficient modeling performance than the PCA model based on complex-valued HRTFs. The PCA model based on HRIRs in the time domain and that based on augmented HRTFs in the frequency domain are shown to be theoretically equivalent. Modeling performance of the PCA model based on log-magnitudes of HRTFs cannot be compared with that of other PCA models because the PCA model deals with log-scaled magnitude components only, whereas the other PCA models consider both magnitude and phase components in linear scale.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.887-894
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• 2007

In this paper, design and fabrication of the LPF with controllable four transmission zeros using electric coupling and added open stub is presented. Pass-band of the LPF is GSM band, and two transmission zeros are generated by the electric coupling at the WiBro and S-DMB band, And the other two transmission zeros are generated by the open stub at the upper frequencies. Harmonic frequency of the stop-band is suppressed by the realization of the filter using quasi-lumped element with small parasitic values. $C_M$, which is the electric coupling element of the equivalent circuit, is realized by the distance control between the open stubs of the filter structure. The fabricated LPF used teflon substrate with relative permittivity of 2.6. And it has a size of $38{\times}20{\times}0.79 mm^3$, which is including a feed line. The measured 3 dB cut-off frequency is 1.55 GHz, and locations of the transmission zeros are 2.20, 2.43, 4.11 and 6.84 GHz, respectively.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.97-102
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• 2000

Subband coding is to divide the signal frequency band into a set of uncorrelated frequency bands by filtering and then to encode each of these subbands using a bit allocation rationale matched to the signal energy in that subband. The actual coding of the subband signal can be done using waveform encoding techniques such as PCM, DPCM and vector quantizer(VQ) in order to obtain higher data compression. Most researchers have focused on the error in the quantizer, but not on the overall reconstruction error and its dependence on the filter bank. This paper provides a thorough analysis of subband codecs and further development of optimum filter bank design using vector quantizer. We compute the mean squared reconstruction error(MSE) which depends on N the number of entries in each code book, k the length of each code word, and on the filter bank coefficients. We form this MSE measure in terms of the equivalent quantization model and find the optimum FIR filter coefficients for each channel in the M-band structure for a given bit rate, given filter length, and given input signal correlation model. Specific design examples are worked out for 4-tap filter in 2-band paraunitary filter bank structure. These optimum paraunitary filter coefficients are obtained by using Monte Carlo simulation. We expect that the results of this work could be contributed to study on the optimum design of subband codecs using vector quantizer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4815-4820
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• 2014

As semiconductor chips are on a small scale, large content and high integratation, it is essential to develop the device of pick and place at the system of the semiconductor test handler to ensure its high precision and durability. In this study, inspection equipment frame model of a semiconductor test handler picker was investigated by vibration analysis with the property of the natural frequency and harmonic response. As 3 kinds of analysis case models, the device of pick and place was located at the left side (Case 1), the center (Case 2) and the right side (Case 3) of the upper guideline. The range of natural frequencies until the 6th order on this frame model ranges from 80Hz to 500Hz. As the analysis of the harmonic response when the frame is resonant, Case 2 showed the maximum equivalent stress of 52.802 MPa more than Cases 1 or 3. Case 2 was the most intensive among the three cases. Using the analysis result of this study, the design of the frame model, which can be applied to the safe working environment of the system is believed to be possible.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.10-18
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• 2018

The primary purposes of this study are to understand a fundamental aspect of current uniformity around a reinforcing bar (rebar) in cement mortar, and to develop an accurate monitoring method in a wet-dry cycling process with the alternative current (AC) impedance method. Three cement mortar specimens with two embedded rebars were prepared in the laboratory. As a main variable, the distance between two rebars was designed to be 10, 20 and 30 mm with the same thickness of 20 mm. To simulate the corrosion of rebars in concrete structures in a marine environment, three cement mortar specimens were exposed to 15 wet-drying cycles (24-hour-immersion in seawater and 48-hour-drying in a room temperature) in the laboratory. It was observed that the potential level shifted to a noble value during corrosion potential monitoring, which is attributed to acceleration of dissolved oxygen diffusion at the drying process. AC impedance was measured in a frequency range from 100 kHz to 1 mHz on a wet-drying process. A theoretical model was proposed to explain the interface condition between the rebars and cement mortar by using the equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE (constant phase element). It was observed that the diffusion impedance appeared in a low frequency range as corrosion of rebars progresses. At the drying stage of the wet-drying cycles, the currents line for monitoring tended to be non-uniform at the interface of rebar/mortar, being phase shift, ${\theta}$, close to $-45^{\circ}$.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.961-966
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• 2003

A Multi-Layer Ceramic (MLC) chip type Band-Pass Filter (BPF) using BiNb$\_$0.975/Sb$\_$0.025/ $O_4$ LTCC (Low Temperature Co-fired Ceramics) and MLC processing is presented. The MLC chip BPF has the benefits of low cost and small size. The BPF consists of coupled stripline resonators and coupling capacitors. The BPF is designed to have an attenuation pole at below the passband for a receiver band of IMT-2000 handset. The computer-aided design technology is applied for analysis of the BPF frequency characteristics. The attenuation pole depends on the coupling between resonators and the coupling capacitance. An equivalent circuit and structure of MLC chip BPF are proposed. The frequency characteristics of the manufactured BPF is well acceptable for IMT-2000 application.