• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.809-814
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• 2011

A method based on the TMS derivatives and acidic hydrolysis was developed for the simultaneous determination of free and conjugated steroidal hormones in surface water. A silylation of five natural and two synthetic steroidal hormones was achieved with N-methyl-N-(trimethylsilyl) trifluoroacetamide/$NH_4I$ (1000:3) under catalysis of dithioerythritol for 60 min at $80^{\circ}C$. TMS derivatives of the steroid hormones containing multifunctional groups offer a single derivative product under this condition. The accuracy of the analytes was in the range of 87 to 110% at a concentration of 20 and 50 ng/L with relative standard deviations of less than 10%. The method detection limit was in the range of 0.01 to 0.02 ng/L for surface water. Natural steroidal hormones were detected in a concentration range of 0 to 1.03 ng/L in free form and 0 to 14.6 ng/L in conjugated form, respectively. We found that most of the natural hormonal steroids exist in conjugate forms (43 to 100%) in river water.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.284-292
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• 2005

Because all of the short-circuit testing laboratories have the limitation of test facilities, the synthetic making test methods have been used to estimate the short-circuit making performance of the ultra high-voltage circuit breaker as the alternative to direct test methods. So, KERI(Korea Eelctrotechnology Research institute) has completed the construction of the synthetic making test facilities using the low capacity step-up transformer method which fulfill the requirements specified in newly revised IEC 62271-100 Edition 1.1(2003) and have the testing capability up to 550kV, 63kA full-pole circuit breaker. The test facilities using the low capacity step-up transformer method presented in this paper are made up of the unit equipments such as HCS(High-speed Closing Switch), ITMC(Initial Transient Making Current) circuit and UP TR(low capacity step-up transformer) and have the operating range of 17.6$^{\circ}$ $\~$ 145.1$^{\circ}$ for testing the circuit breaker rated on up to 50kA and 43.1$^{\circ}$ $\~$ 119.6$^{\circ}$ for more than 50kA.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권4호
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• pp.145-151
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• 2005

The synthetic breaking test method was developed to evaluate the breaking performance of ultra high-voltage circuit breaker and made up of two independent circuits; current source circuit and voltage source circuit. In application of this test method, it is necessary to extend the arc of the test breaker. So, the new re-ignition system using VTGS (Vacuum Triggered Gap-Switch) was constructed to improve the efficiency and reliability of this test. In this re-ignition system, VTGS operates in high vacuum state of $5{\time}10^{17}$torr and control system consists of the triggering device and the air M-G (Motor-Generator). This re-ignition system showed the operating characteristics, such as delay time ($t_d$) and jitter time ($t_j$ not exceeding 5us and 1us respectively, and had the operating voltage of $25\~150kVdc$ at the gap distance of 24mm.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.183.3-184
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• 2002

• 대한전기학회:학술대회논문집
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• 대한전기학회 1983년도 하계학술회의강연.논문초록집
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• pp.98-100
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• 1983

• Bulletin of the Korean Chemical Society
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• 제19권1호
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• pp.132-134
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• 1998

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.759-760
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• 2000

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1216-1218
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• 1997

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.778-783
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• 2012

The synthetic short-circuit making test to adequately stress the circuit breaker has been specified as the mandatory test duty in the IEC 62271-100. The purpose of this test is to give the maximum pre-arcing energy during making operation. And this requires the making operation with symmetrical short-circuit current that is established when the breakdown between contact gap occurs near the crest of the applied voltage. Also, if the interrupting chamber of circuit breakers is designed as the type of common enclosure or the operation is made by the gang operated mechanism that three-phase contacts are operated by one common mechanism, three-phase synthetic making test is basically required. Therefore, several testing laboratories have developed and proposed their own test circuits to properly evaluate the breaker performance. With these technical backgrounds, we have developed the new alternative three-phase making circuit.

• 조명전기설비학회논문지
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• 제25권7호
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• pp.105-113
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• 2011

The study about three-phase synthetic making test using DC power has been performed in order to increase the making test capacity on Vacuum Circuit Breaker. And, it made possible to solve the limitations that short-circuit testing facilities can not fulfill the testing requirements of VCB exceeding three-phase 36[kV] 31.5[kA]. By using DC power and high speed spark-gap switch, this method made the equivalence with the pre-arc that occurred during the making process under the fault condition of power system. As results, KERI(Korea Electrotechnology Research Institute) could have capacity to carry out type test for VCB under three-phase 52[kV] 40[kV], which satisfies the IEC Standard.