• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.954-962
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• 1996

Four kind of polysilanes which had side chains of methyl, phenyl, and mixed structures, were synthesized and modified by doping with iodine. The structural, thermal, and electric characteristics of obtained polymers were systematically observed with iodine, The structural, thermal, and electric characteristics of obtained polymers were systematically observed with FT-IR, UV/VIS, TGA/DTG, DSC, and measurement of electric conductivity. From FT-IR spectra, it was confirmed that the synthesized polysilanes had side chains of methyl, phenyl, and mixed structures. The thermal stabilities of the polymers were found to increase with phenyl substituents. The polysilanes with phenyl side groups showed ${\sigma}-{\sigma}*$ transition absorption at wavelengths longer than 350 nm. The bathochromic shift of polysilanes with phenyl substituents relates probably to the narrowed band gap caused by delocalization of ${\pi}$-electron. The polymers doped with iodine showed multi-step pyrolysis behavior and higher residue compared with that of the undoped polymers. The electric conductivities of the undoped and doped polysilanes were $10^{-5}S/cm$ and $10^{-4}S/cm$, respectively.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.195-201
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• 2013

In atherosclerosis, blood vessels become sensitive to vessel-constricting agents leading to reduced control in the event of abrupt blood pressure changes. Mulberry trees (Morus alba L., MA) have been claimed to contain various bioactive principles that could possibly prevent atherosclerosis development caused by high cholesterol consumption. In order to examine whether MA feeding can prevent the sensitization of blood vessels, MA leaves were fed to rats for 8 weeks and pressor responses to vasoconstricting agents were assessed. Animals were pithed before blood pressure assessments to eliminate reflex compensation in vessel responses. Feeding diets containing high levels of cholesterol led to potentiated pressor responses to sympathetic nerve stimulation, or to injection of norepinephrine, phenylephrine, angiotensin II and vasopressin in pithed rats. These potentiated pressor responses were prevented in rats fed MA leaf-containing diets at 2 or 10% levels. It was also examined in anesthetized non-pithed rats whether similar cholestrol-related sensitization and MA prevention could be observed. However, high cholesterol-induced sensitization in pressor responses were not observed, suggesting that destruction of central cardiovascular control by pithing must have revealed the sensitization responses. It was concluded that MA leaves seem to be active in preventing abnormal blood vessel reactivity caused by hypercholesterolemia.

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.174-177
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• 1993

Ultara violet ray air cleaner to use as the sterilization and deodorization device in refrigerator was designed and made of UV lamp and carbon block as the main components. The intensity of the lamp was $2.38\;mW/cm^2$ and reflector was installed to increase the radation. After running the device for 12 hours, 80% of the population of airborn bacteria was sterilized both at 48 and 480 liter refrigerator chambers. Ozone production caused by UV-ray reached 0.082 ppm at holding section within a few second when the device was operated at $25^{\circ}C$ and it showed 0.06 pm at $3^{\circ}C$. Deodorization effect was 2.5 times greater than that of a device made of electrical are principle at $25^{\circ}C$. New device 2 times more effectivly decreased trimethylamine and methyl mercaptan content applied as odor indicator substance in chamber at $3^{\circ}C$ than electrical arc type.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.71-74
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• 1991

구조물의 진동특성을 파악하기 위한 실험적 모우드 해석법에서 기진력을 제 공하는 한 방법으로 힘 측정기가 부착된 해머를 이용한 충격시험기법이 널 리 사용되고 있다. 충격해머 시험의 유용성은 기진력의 에너지가 정현파 기 진력의 경우처럼 특정 주파수대에 산재해 있는 것이 아니라 가용 주파수 영 역내에 연속적으로 분포해 있다는 점이며 이러한 충격력은 가용 주파수 범 위내에 있는 모든 고유진동형을 여가시킬 수 있다는 장점이 있다. 충격헤머 가 가지고 있는 동적특성은 구조물을 가진시키는 선형충격량의 크기를 결정 하며, 이는 다시 충격력의 크기와 가용 주파수 범위를 결정하게 된다. 일반 적으로 가진주파수 범위는 해머의 질량에 반비례하고 충격해드의 경도에 비 례하는 것으로 알려져 있다. 해머의 질량 자체가 충격력의 크기를 좌우하기 도 하므로, 가진력의 크기를 고려하여 해머의 질량이 선택되며 충격헤드는 충격시간을 조절하기 위하여 적절히 선택된다. 충격해머에 장착된 힘측정기 의 감도는 해머질량과 충격헤드의 질량 변화에 영향을 받게 되는데, 충격 시 험시 측정되는 값은 해머에 부착되어 있는 힘측정기에 가해지는 힘인 반면 구조물에 가해지는 기진력은 충격해드와 구조물사이에 발생되는 힘이다. 이 두 힘의 비는 해머 및 충격해드의 질량효과에 따라 좌우된다. 주어진 충격시 험에서 충격해머의 질량효과를 정확히 조건에 따라 감도보정을 해 주어야 한다. 충격해머의 감도보정에 대해서는 문헌[2]에 잘 나타나 있다. 본 논문에 서는 전압감도에 미치는 영향을 파악하고자 질량 효과를 고려한 수학적 모 형을 제시하고 그 모형의 타당성을 실험을 통해 검정하고자 한다.방법 을 제시하였다. 이와 아울러 제어계의 환경변화에 따른 파라메타의 변화에 적응적으로 응답이 가능해야 하는 적응 소음제어 시스템에서, 음향궤환과 함 께 필히 고려해야 하는 부가적인 전달함수의 영향을 고려한 능동 소음제어 에 대해 연구하였다. 경량화 추세에 따라 지반이나 케이싱이 경량이거나 유연하여 회전축과 동적으로 연성된 경우 회전축-베어링-지반으로 이루어진 2중구조의 회전축 계 동특성을 해석할 수 있는 프로그램을 개발하므로서 회전 기계류의 진동 전반에 걸친 문제점에 대한 그 원인과 현상을 명확히 분석하여 국내의 전기 계류의 보다 신뢰성있는 설계 및 제작자료를 확보하는데 기여할 수 있게 하 였다.존의 small molecular Gd-chelate에 비해 매우 큼을 알 수 있었다. MnPC는 간세포에 흡수된 후 담도계로 배출되는 간특이성 조영제임을 확인하였다. 장비 내에서 반복 시행한 평균값의 차이는 대체적으로 유의한 차이가 없었으나, 다른 장비에서 반복 시행한 장비간의 사이에는 유의한 차이가 있는 경우가 더 많았다. 따라서 , MRS 검사를 소뇌나 뇌교의 어떤 절환에 적용하기 전에 각 장비 마다 정상 기준치를 반드시 얻은 후에 이상여부를 판 정하는 것이 필수적이라고 생각된다.EX> 이상이 적절한 진단기준으로 생각되었다. $0.4{\;}\textrm{cm}^3$ 이상의 좌우 부피차를 보이는 모든 증례에서 육안적으로도 해마위축이 뚜렷이 나타났다. 결론 : MR영상을 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다

• Journal of Soil and Groundwater Environment
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• v.14 no.1
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• pp.29-35
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• 2009

In this study, the effect of pH and temperature on the adsorption behavior of acid mine drainage (AMD) on coal mine drainage sludge (CMDS) has been investigated during the treatment of coal mine drainage (CMD) by electrical purification method. The pH$_{zero\;point\;charge}$ (pH$_{zpc}$) of CMDS was 5. The removal ratio of copper, zinc, cadmium, iron were increased according to the increase of pH value. The adsorption amount of copper showed 0.64 mg g$^{-1}$ sludge. It was independent of pH value. The adsorption amount of the other metals showed l.l times when pH was 3. The adsorption amount of chromium was a little bit increased at the pH value higher than 7 due to a small amount of the chromium was eluted as $Cr(OH)_6^{3-}$. The amount of metals' absorption were decreased according to temperature was increase at pH value was 3. The selectivity order was Cd>Fe > Zn > Cu. The amount of absorption showed q$_{max}$ Cu 2.747 mg g$^{-1}$ andZn 2.525 mg g$^{-1}$ when pH value higher than 5. It was independent of temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.203-209
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• 1983

The occurrence and regional distribution of low temperature and drought during rice cropping period in Korea were studied to characterize the climatic impacts. The long term changes in rice yield, air temperature and precipitation were analyzed, and regional distributions were characterized. The significant climatic impacts on rice yield were heavy rain or flood, drought and low temperature. Since 1910, the occurrence of drought was 29 times, that of flood was 24 times and that of low temperature was 9 times; however, the drought and flood damages were decreased due to expansion of irrigation system since 1970 but low temperature damage was remarkedly increased. The long term changes in air temperature since 1908 in Suweon showed that the 5-year moving average from July to August decreased while that from May to June increased. The occurrence probability of the long term and early term low temperature types were the greatest in Korea and were in order of Suweon, Daegu and Kwangiu. The long term changes in 10-year moving average precipitation from April to June showed a 15 year cycle and recent years were in low precipitation period. The drought frequencies were the highest in Daegu and Pohang area. According to the precipitation from April to June and resevtoir storage at late June, the severest dry area were the Youngnam inland and the southwest coastal area.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.169-181
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• 2002

Basic~intermediate dike swarms are pervasively developed in the east of the Ulsan Fault, SE Korea. Most of them intruded initially along the NS-trending extensional fractures which developed under EW extension during the East Sea opening in the Early Miocene (before about 17 Ma). The mean-strikes of the basic dikes intruding into the granites are more clockwise rotated in farther eastern side, i. e.$ N06^{\circ}$E, $Nl5^{\circ}$E, and $N37^{\circ}$E in the western side, in the just vicinities, and in the eastern side of the YBonil Tectonic Line (YTL), respectively. And the mean-strike of the basic dikes nearby shoreline is also most clockwise rotated ($N75^{\circ}$E in the Guryongpo Peninsula). The spatial variance indicates that the dikes, located only in the east of the YTL, experienced horizontal-clockwise rotation, and that the dikes in farther east from the YTL experienced more clockwise rotation. It is, thus, supported that the NNW dextral shear stress, generated by the spreading of the East Sea, was propagated toward inland from eastern continental margin of the Korean Peninsula, and that the YTL is an westernmost limit of the clockwise crustal rotations which are pervasively observed in the vicinities of the Miocene basins, SE Korea.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.907-915
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• 2013

Tire Pressure Monitoring System (TPMS) is an auxiliary safety system for recognizing the condition of tires based on the pressure and temperature data transmitted from the sensor unit installed on a tire of the vehicle. Using TPMS, a driver can frequently check the state of tires and it aids to maintain the optimum running condition of the vehicle. Since TPMS must utilize the wireless communication technique to transmit data from a sensor unit to a signal processing unit installed in the vehicle, it suffers from interference signals caused by various external electrical or electronic devices. In order to suppress high-power interference signals, we employ beamforming techniques based on the uniform linear antenna array. As the number of the antennas is increased, the performance of the interference suppression is improved. However, there is the limit of the number of antennas, installed in the center of a vehicle, because of its size. In this paper, we compare and analyze the performance of the beamformer, when reducing the interelement spacing of antennas, to increase the number of the receiving antennas. For the performance analysis of the beamformers, we consider the switching beamformer and minimum-variance distortionless-response (MVDR) beamformer for TPMS, recently proposed.

• 월간산업보건
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• s.356
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• pp.16-25
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• 2017

Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidationreduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 ; 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 ; 89.9) at 1 hour and 81.0% (78.3 ; 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 ; 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.69-74
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• 2018

Large industrial motors require a large area because of the high risk of shutdown accidents and large industrial accidents due to the lowering of the dielectric strength of the armature windings and overheating problems. Therefore, there is a demand for a large-capacity motor that has small size, light weight, and excellent dielectric strength compared with conventional motors. Superconducting motors have advantages of high efficiency and output power, low size, low weight, and improved stability. This results from greatly increasing the magnetic field generation by using superconductive field coils in rotating machines such as generators and motors. It is very important to design and analyze the cooling system to lower the critical temperature of the wires to achieve superconducting performance. In this study, a field loss analysis and low-temperature heat transfer analysis of the cooling system were performed through the conceptual design of a 100-HP high-temperature superconducting synchronous motor. The field loss analysis shows that a uniform pore magnetic flux density appears when high-temperature superconducting wire is used. The low-temperature heat transfer analysis for gaseous neon and liquid neon showed that a flow rate of 1 kg/min of liquid neon is suitable for maintaining low-temperature stability of the high-temperature superconducting wire.