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Thermal Diffusivity of PEEK/SiC and PEEK/CF Composites (PEEK/SiC와 PEEK/CF 복합재료의 열확산도에 대한 연구)

  • Kim, Sung-Ryong;Yim, Seung-Won;Kim, Dae-Hoon;Lee, Sang-Hyup;Park, Joung-Man
    • Journal of Adhesion and Interface
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    • v.9 no.3
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    • pp.7-13
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    • 2008
  • The particulate type silicon carbide (SiC) and fiber type carbon fiber (CF) filler, of similar thermal conductivities, were mixed with polyetheretherketone (PEEK) to investigate the filler effects on the thermal diffusivity. The SiC and CF fillers had a good and uniform dispersion in PEEK matrix. Thermal diffusivities of PEEK composites were measured from ambient temperature up to 200C by laser flash method. The diffusivities were decreased as increasing temperature due to the phonon scattering between PEEK-filler and filler-filler interfaces. Thermal diffusivity of PEEK composites was increased with increasing filler content and the thermal conductivities of two-phase system were compared to the experimental results and it gave ideas on the filler dispersion, orientation, aspect ratio, and filler-filler interactions. Nielson equation gave a good prediction to the experimental results of PEEK/SiC. The easy network formation by CF was found to be substantially more effective than SiC and it gave a higher thermal diffusivities of PEEK/CF than PEEK/SiC.

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Optimum Treatment Parameters for Photodynamic Antimicrobial Chemotherapy on Streptococcus mutans Biofilms (Streptococcus mutans biofilm에 대한 광역동 치료의 최적조건에 관한 연구)

  • Choi, Seojung;Park, Howon;Lee, Juhyun;Seo, Hyunwoo;Lee, Siyoung
    • Journal of the korean academy of Pediatric Dentistry
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    • v.42 no.2
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    • pp.151-157
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    • 2015
  • The purpose of this study was to evaluate the effects of Photochemotherapy using a combination of erythrosine and standard halogen dental curing lights on the viability of Streptococcus mutans in the biofilm phase. To investigate the optimum treatment parameters, the researchers controlled the concentration of erythrosine, light irradiation time and the treatment time of erythrosine. The higher concentration of erythrosine (0, 10, 20, 40, 80 M) in the presence of light irradiation created greater effects in reducing the viability of S. mutans. The results showed a statistically significant difference among the antimicrobial effects in 20, 40, 80 M erythrosine. The higher irradiation time of light (0, 5, 15, 30, 60, 75s) in the presence of erythrosine showed greater effects in reducing the viability of S. mutans. There was statistically significant difference in 30, 60, 75 seconds. The higher treatment time of erythrosine (0, 1, 2.5, 5min) in the presence of erythrosine created greater effects on reduction of S. mutans viability. Statistically significant differences were found between 2.5 and 5 minutes of erythrosine treatment time. The results of this study showed that the photochemotherapy on S. mutans using erythrosine and the halogen dental curing lights conventionally used in dental clinics is effective in the condition of 20-40 M erythrosine concentration, irradiation time over 30 seconds, and erythrosine treatment time over 2.5 minutes.

A Study on Applicability of API-581 and Methodology for Consequence Analysis in High-Pressure Toxic Gas Facilities (고압 독성가스시설에서 API-581 적용성 및 사고결과 분석방법에 관한 연구)

  • Jang, Seo-Il;Kim, Youngran;Park, Kyoshik;Shin, Dongil;Kim, Tae-Ok
    • Journal of the Korean Institute of Gas
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    • v.18 no.4
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    • pp.76-85
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    • 2014
  • To establish the necessary safety technology in high-pressure toxic gas facilities, especially for the corrosion, which is the main causes of toxic gas accident, this study adopts and investigates the API-581 procedures developed by the American Petroleum Institute (API). And the applicability of the 8-step analytical procedures of consequence analysis in API-581 is discussed, and a method for consequence analysis in high-pressure toxic gas facilities is suggested. Based on the discussion and results, the analytical procedure is simplified as the 6 steps in total for the effective application to high-pressure toxic gas facilities: Step 1 (determination of representative material), Step 5 (determination of release type), Step 6 (determination of phase of fluid), and Step 8 (estimation of damage range) are not applied: Step 3 (estimation of total amount of release) is applied only for the inventory group concept; Step 4 (estimation of release rate) only for the gas release rate; and all of Step 2 (selection of release hole size) and Step 7 (evaluation of post-release response) are applied. In the proposed method, the generally applicable method of CCPS is adopted as alternative method for Steps 5 and 8.

The Short-term Effects of Soil Brought and Subsoil Inversion on Growth and Tissue Nutrient Concentrations of Fraxinus rhynchophylla, Pinus densiflora, and Pinus koraiensis Seedlings in a Nursery (객토와 심토뒤집기 처리가 물푸레나무, 소나무, 잣나무 묘목의 초기 생장과 양분함량에 미치는 영향)

  • An, Ji Young;Park, Byung Bae;Byun, Jae Kyung;Cho, Min Seok;Kim, Yong Suk;Han, Si Ho;Kim, Se Bin
    • Journal of Korean Society of Forest Science
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    • v.104 no.1
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    • pp.43-49
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    • 2015
  • The production of high quality seedlings is a very important phase in silvicultural systems for successful reforestation or restoration. The purpose of this study was to quantitatively measure both growth performances and nutrient responses of Fraxinus rhynchophylla, Pinus densiflora, and Pinus koraiensis seedlings, which are commercially planted in Korea, according to the different types of soil improvement treatments. We applied soil brought (hereafter 'brought'), subsoil inversion (hereafter 'subsoil'), and mixture of brought soil with soil on nursery bed (hereafter 'mixing') in a permanent national nursery. Silt and clay contents were the highest at the subsoil treatment and organic material, soil nitrogen and phosphorus concentrations were the lowest at the brought treatment. The growth of F. rhynchophylla was the lowest at the subsoil treatment, but there were no significant differences among treatments. There were significant differences in only root nutrient concentrations of F. rhynchophylla among treatments: nitrogen, phosphorus, and potassium concentrations were the lowest at the subsoil or brought treatment. Mixing treatment increased N contents with deduction of N concentrations ('dilution') because of more dry weight increase compared with the amount of N uptake. This study suggested mix of brought soil with soil on a nursery bed in a permanently used nursery can economically be an effective technique to improve soil quality.

Generation of Ionospheric Delay in Time Comparison for a Specific GEO Satellite by Using Bernese Software

  • Jeong, Kwang Seob;Lee, Young Kyu;Yang, Sung Hoon;Hwang, Sang-wook;Kim, Sanhae;Song, Kyu-Ha;Lee, Wonjin;Ko, Jae Heon
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.3
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    • pp.125-133
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    • 2017
  • Time comparison is necessary for the verification and synchronization of the clock. Two-way satellite time and frequency (TWSTFT) is a method for time comparison over long distances. This method includes errors such as atmospheric effects, satellite motion, and environmental conditions. Ionospheric delay is one of the significant time comparison error in case of the carrier-phase TWSTFT (TWCP). Global Ionosphere Map (GIM) from Center for Orbit Determination in Europe (CODE) is used to compare with Bernese. Thin shell model of the ionosphere is used for the calculation of the Ionosphere Pierce Point (IPP) between stations and a GEO satellite. Korea Research Institute of Standards and Science (KRISS) and Koganei (KGNI) stations are used, and the analysis is conducted at 29 January 2017. Vertical Total Electron Content (VTEC) which is generated by Bernese at the latitude and longitude of the receiver by processing a Receiver Independent Exchange (RINEX) observation file that is generated from the receiver has demonstrated adequacy by showing similar variation trends with the CODE GIM. Bernese also has showed the capability to produce high resolution IONosphere map EXchange (IONEX) data compared to the CODE GIM. At each station IPP, VTEC difference in two stations showed absolute maximum 3.3 and 2.3 Total Electron Content Unit (TECU) in Bernese and GIM, respectively. The ionospheric delay of the TWCP has showed maximum 5.69 and 2.54 ps from Bernese and CODE GIM, respectively. Bernese could correct up to 6.29 ps in ionospheric delay rather than using CODE GIM. The peak-to-peak value of the ionospheric delay for TWCP in Bernese is about 10 ps, and this has to be eliminated to get high precision TWCP results. The 1016 level uncertainty of atomic clock corresponds to 10 ps for 1 day averaging time, so time synchronization performance needs less than 10 ps. Current time synchronization of a satellite and ground station is about 2 ns level, but the smaller required performance, like less than 1 ns, the better. In this perspective, since the ionospheric delay could exceed over 100 ps in a long baseline different from this short baseline case, the elimination of the ionospheric delay is thought to be important for more high precision time synchronization of a satellite and ground station. This paper showed detailed method how to eliminate ionospheric delay for TWCP, and a specific case is applied by using this technique. Anyone could apply this method to establish high precision TWCP capability, and it is possible to use other software such as GIPSYOASIS and GPSTk. This TWCP could be applied in the high precision atomic clocks and used in the ground stations of the future domestic satellite navigation system.

EFFECT OF PATIENT'S BREATHING PATTERN ON THE STRESS CHANGES IN THIRD MOLAR EXTRACTION (제 3 대구치 발치시 환자의 호흡 패턴이 스트레스 변화 양상에 미치는 영향)

  • Rhee, Sang-Myung;Kim, Hyung-Wook;Park, Yang-Ho;Kim, Jin-Cheol;Park, Jun-Woo;Rhee, Sung-Jun;Nyamdorj, Selenge;Ahn, Jae-Mok
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.33 no.5
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    • pp.485-493
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    • 2007
  • Purpose: Heart rate variability(HRV) is the clinical consequence of various influences of the autonomic nervous system(ANS) on heart beat. HRV can estimate the potential physiologic rhythm from the interval between consecutive beats(RR interval or HRV data). It is known as RSA which represents respiration-related HR rhythmic oscillation. Previous studies demonstrated a specific breathing pattern(0.1Hz, 6breaths/min) to improve a physiological body condition related to the stress. In this paper, the level of stress would be evaluated in terms of three phases of the dental treatment, combined with 6breaths/min. Methods: These phases include before, during and after tooth extraction or anesthesia or something.36 patients' stresses were assessed using HRV stress analyzer in each phase in Kangdong Sacred Heart Hospital, and Chuncheon Sacred Heart Hospital, Hallym University Medical Center from Jun. to Sept. of 2007. HRV 5-min data collected were analyzed in time-domain and frequency-domain to evaluate the activity of autonomic nervous system(ANS) which represents the level of stress. Results: All HRV parameters including HF(high frequency), LF(low frequency) and LF/HF ratio showned a significant change affecting the ANS balance. There was a 6.4% difference between R(LF/HF)s on general breathing pattern for balance of Autonomic nervous system, but on controlled breathing pattern, 0.1Hz, was made narrow till 1.4%. The activity of ANS has increased by 1.4% on general breathing pattern, and by 2.9% on controlled breathing pattern, 0.1Hz. Conclusion: After analysis of preoperative stress changes and effect of breathing pattern of 0.1 Hz on the stress in 36 patients who have undergone third molar extraction, following was concluded. In the preoperative stage, the sympathetic change was the greatest?after the?anesthetic injection, and stress was relieved by controlling the breathing pattern to a frequency of 0.1Hz.

Design and Implementation of High Efficiency Transceiver Module for Active Phased Arrays System of IMT-Advanced (IMT-Advanced 능동위상배열 시스템용 고효율 송수신 모듈 설계 및 구현)

  • Lee, Suk-Hui;Jang, Hong-Ju
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.7
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    • pp.26-36
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    • 2014
  • The needs of active phased arrays antenna system is getting more increased for IMT-Advanced system efficiency. The active phased array structure consists of lots of small transceivers and radiation elements to increase system efficiency. The minimized module of high efficiency transceiver is key for system implementation. The power amplifier of transmitter decides efficiency of base-station. In this paper, we design and implement minimized module of high efficiency transceiver for IMT-Advanced active phased array system. The temperature compensation circuit of transceiver reduces gain error and the analog pre-distorter of linearizer reduces implemented size. For minimal size and high efficiency, the implented power amplifier consist of GaN MMIC Doherty structure. The size of implemented module is 40mm×90mm×50mm and output power is 47.65 dBm at LTE band 7. The efficiency of power amplifier is 40.7% efficiency and ACLR compensation of linearizer is above 12dB at operating power level, 37dBm. The noise figure of transceiver is under 1.28 dB and amplitude error and phase error on 6 bit control is 0.38 dB and 2.77 degree respectively.

The Effect of Pre and Intra-Operative Warming Therapy on Tympanic Temperature Changes during Perioperative Phase in Receiving Patients with Total Hip Replacement (수술전과 수술중 피부가온요법 적응이 고관절 전치환술 환자의 수술 주기 고막체온 변화에 미치는 영향)

  • Kwon Young-Sook;Kim Eun-Hee
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.7 no.1
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    • pp.86-96
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    • 2000
  • The purpose of the study was to investigate the effects of Warming Therapy used with patients consistantly before and during surgery to on changes in their body temperatures. The data were collected from patients in a university hospital in Taegu between December 1, 1998 and May 31, 1999. The subjects were selected from patients who were hospitalized for total hip replacement surgery. Thirty participants were assigned to two groups : experimental(Warming Therapy) group and control group. Each group consisted of 15 patients. The research design was a repeated measurement design, using a nonequivalent control group. The Warming Therapy, using a forced-air warming blanket, that is a, 'Bair Hugger' was applied to subjects in the experimental group. The subjects in the group were treated with the 'Bair Hugger' to warm up the whole body for 40 minutes before surgery and upper body and face during the operation. The core temperature was measured using a tympanic thermometer. The body temperature of the patients was measured 13 times every 15 minutes during the surgery. After the operation the body temperature of the patients was measured 4 times every 15 minutes, from the time of arrivial in the recovery room to the time of leaving the recovery room. The SPSS Win 9.0 program was used for data analysis. Specific methods tested were done using χ2test, t-test, repeated measures ANOVA. The findings of the study are as follows. 1. The first hypothesis, 'The level of tympanic temperature for the experimental group which received Warming Therapy will be higher than that of the control group during the operation', was supported (F=32.16, p=.000). 2. The second hypothesis, 'The level of tympanic temperature for the experimental group which received Warming Therapy will be higher than that of the control group after the operation', was supported.(F=33.36, p=.000) 3. During recovery, shivering was observed one patient in the experimental group and seven patients in the control group. In summary, the findings of the study suggest that the 'Warming Therapy' applied before and during the surgery was a very effective treatment for surgical patients in maintaining the core temperature during surgery

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Electron Paramagnetic Resonance Study of impurity Fe3+ ion in LiTaO3 single crystal (Fe3+ 불순물이 첨가된 LiTaO3 단결정에서의 전자 상자성 공명 연구)

  • Min, S.G.;Yeon, T.H.;Lee, S.H.;Lee, M.K.;Shin, H.K.;Yu, Y.M.;Kim, T.H.;Yu, S.C.
    • Journal of the Korean Magnetics Society
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    • v.13 no.4
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    • pp.171-175
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    • 2003
  • Electron paramagnetic resonance (EPR) of Fe3+ in LiTaO3 single crystal, grown by Czochralski method, has been studied by employing an X-band spectrometer. Resonance spectra of Fe3+ ion on the crystallographic principal axes were obtained with 9.447 ㎓ at room temperature. The spectroscopic splitting parameter g and zero-field splitting (ZFS) parameter D (= 3 B2sup 0/) are calculated with effective spin Hamiltonian. Fe3+ center in stoichometric single crystal turns out to be different with that in congruent single crystal reported previously. From the analysis of temperature dependence of resonance fields for Fe3+ ion, there is no any phase transition at the temperature range (from -160 C to 20 C).

Radionuclide Diffusion in Compacted Domestic Bentonite (압축 국산 벤토나이트 내에서 방사성 핵종의 확산이동)

  • Choi, Jong-Won;Lee, Byung-Hun
    • Journal of Radiation Protection and Research
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    • v.16 no.2
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    • pp.27-39
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    • 1991
  • The diffusion of Sr-85, Cs-137, Co-60 and Am-241 in compacted domestic bentonite was studied, using a diffusion cell unit in which diffusion took place axially from the center of cylindrical bentonite sample body. The effects of compaction density and heat-treated bentonite on diffusion were analysed. And the diffusion mechanism of radionuclide was also analysed by evaluating the measured diffusivity of anion Cl-36. The apparent diffusivities obtained for Sr-85, Cs-137, Co-60 and Am-241 were l.07×1011,6.705×1013,l.226×1013andl.310×1014m2/sec, respectively. When the as-pressed density of bentonite increased from 1.8to2.0g/cm3, the apparent diffusivity of Cs-137 decreased by quarter. In the case of bentonite heat-treated to 150C, no significant change in diffusivity was observed, which showed the possibility that the domestic bentonite could be used as a chemical barrier to retard the radionuclide migration at below 150C. From the calculated pore and surface diffusivity, the surface diffusion due to the concentration gradient of radionuclide sorbed on the solid phase was found to dominate greatly in total transport process.

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