• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.289-293
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• 1993

A Nd:YLF laser pumped by a CW GaAlAs laser diode(LD) at 792 nm has been designed and fabricated. The output power was investigated as a function of LD spectrum and pump power. A folded laser resonator was desinged to compensate for the astigmatism produced at the Brewster surface of Nd:YLF rod. We obtained output power of CW 1.1 Watt when the pumping power was 2.8 Watt and the output wavelength of LD was temperature tuned to the peak absorption line of Nd:YLF. The overall efficiency was 39 % and slope efficiency was 41 %.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.131-133
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• 2014

Vibration exposure of the KTX and ITX-saemaeulho on the Gyung-Bu line was evaluated and compared in terms of human health based on ISO 2631. RMS value of KTX was calculated as much lower than ITX-saemaeulho in all travel sections. When VDV result of the two trains drived return travel from Seoul to Busan in single day is compared on the health guidance caution zone of ISO 2631, vibration exposure of KTX is safer than ITX-saemaeulho which is marginally under the caution line.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.508-512
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• 2007

하천유량자료는 이수, 치수, 수질관리 등의 목적으로 널리 사용되기 때문에 여러 가지 수문관측 자료 중 가장 중요하다고 할 수 있다. 그러나 우리나라의 유량자료는 여러 가지 한계를 가지고 있어서 수문자료로서 제대로 사용되지 못하고 있는 실정이다. 특히 홍수기 부자측정 방법에 의해 산정된 유량자료는 측정 여건, 방법, 기기 등의 한계로 인해 그 정확도가 더욱 낮다. 부자에 의한 유량측정은 일정거리를 유하하는 부자의 유하시간을 측정하여 평균유속을 구하고, 사전에 측량된 횡단면으로부터 유하한 개별 부자의 해당 단면적을 구하여 부분 단면적을 구한다. 구해진 개별 부자의 평균유속과 부분 단면적을 곱하여 부분유량을 산출한 후, 각 부분유량을 합하여 전체 유량을 계산한다. 이와같은 부자법은 유속-면적법이 가지고 있는 흐름 단면적 계산, 평균유속 계산의 불확실도 이외에 유하경로에 의한 불확실도, 부자 유하 시간의 불확실도, 유속 보정 계수의 불확실도 등을 포함한다. 기존 홍수 유량측정에 사용하고 있는 부자법은 육안에 의해 부자의 위치를 파악하고, 가상의 횡단선을 통과할 때 육안으로 관측하여 유하시간을 측정하는 방법이기 때문에 정확한 유량측정에 한계가 있다. 뿐만 아니라 측정에 다수의 인원이 필요하며, 홍수시 많은 비가 내리거나, 야간에 측정하는 경우에는 부자의 식별이 곤란하고 측정 여건이 불량하기 때문에 측정에 큰 애로가 있다. GPS를 이용한 전자부자는 자동으로 유속을 측정하기 위해 기존 홍수유량 측정에 사용하던 부자에 전자장치를 추가하는 것을 말한다. 본 연구에서는 GPS와 RF를 기존 봉부자에 추가하여 봉부자의 유속과 봉부자의 괘적을 측정할 수 있는 전자부자를 개발하였다. 개발한 전자부자는 기존 육안에 의한 방식보다 자동으로 정확한 유속 측정이 가능하며, 동시에 여러 개의 봉부자 사용이 가능하여 측정시간 절감이 가능하고, 비가 내리거나 야간에도 자동으로 측정이 가능한 특징을 지니고 있다. 본 연구에서 개발된 전자부자는 3개 주파수 대역을 이용할 수 있도록 개발하여, 총 15개의 부자를 동시에 투하할 수 있도록 개발하였다. 전자부자 시험결과 50m, 100m 구간 유속을 검증한 결과 50m의 경우 최대 평균 5.97%, 평균 2.38%의 상대오차를 나타냈으며, 100m의 경우 최대 5.43%, 평균 1.9%의 상대오차를 나타냈다. 자연하천 유량측정 결과 댐 방류량 대비 기존방법의 경우 약 8.2%의 상대오차를 지니고 있었으며, 전자부자의 경우 약 2.8% 상대오차를 지니고 있어, 기존 부자법에 비해 전자부자법이 5.4%의 상대오차 개선효과를 지니고 있었다. 이와같은 오차의 범위는 실제 하천에서 전자부자를 이용하여 유속측정이 가능함을 나타내는 결과이다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.4
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• pp.266-274
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• 2015

Vibration exposure of domestic high speed trains(KTX and ITX-saemaeulho) to passenger traveling on the Gyung-Bu line was measured to evaluate health effect which is based on ISO 2631-1. The vibration exposure was compared with the frequency weighted root mean square(r.m.s.) and vibration dose value(VDV) of the two trains’ vibration. It is concluded that vibration exposure of the two train during round trip of Busan-Seoul in single day is evaluated to be safe for the passenger’s health according to the health guidance caution defined on ISO 2631-1. Futhermore KTX’s vibration exposure is found to be significantly lower than ITX-saemaeulho thanks to lower vibration magnitude as well as shorter trip time.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.207-211
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• 2013

In this research, the pH sensor was developed using CNT nanosheet with Nafion coating for the advanced medical sensor such as a blood gas analyzer. The CNT nanosheet was formed by dielectrophoresis and water-meniscus between cantilever-type electrodes. Then, the process of the heat annealing and the Nafion coating was conducted for reducing contact resistance and giving proton selectivity respectively. We measured the response of the pH sensor as the electrolyte-gated CNT-nanosheet field effect transistor. The sensor showed a linear current ratio in a similar range of the normal blood pH. A calibration method for decreasing of the response variation among sensors has also been introduced. Coefficient of variance of the pH sensor was decreased by applying the calibration method. A linear relation between the calibrated response of the sensors and pH variance was also obtained. Finally, the pH sensor with a high resolution was fabricated and we verify the feasibility of the sensor by applying the calibration method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.145-148
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• 2008

Recently, most of the international design code for concrete structures are trying to develope performance-based design specification with the limit state concept. To accomplish this object, it is necessary to define required performance and to measure the performance level of structure. The reliability index is one of the most attractive indexes to express the level of performance. In this paper, prestressed concrete beam is designed following member resistance factor and material resistance factor format and the reliability indexes are obtained and compared for different sets of resistance factors. Compatible sets of safety factors could be calibrated for given level of target reliability index applying the similar method presented in this paper.

• Journal of Energy Engineering
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• v.16 no.4
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• pp.155-163
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• 2007

To insure nuclear reactor safety, the reactivity of control rods should be calculated by measuring the criticality of reactor core and it is regularly performed during the annual physics test period. Also, the core criticality should be monitored during the start-up operation to avoid reactivity induced accidents. Many research works on control rod reactivity measurement and subcriticality measurement have been accomplished throughout the world for decades and recently a new method named "Modified Neutron Source Multiplication Method (MNSM)" was proposed in Japan which is known to be improved overcoming limitations of traditional Neutron Source Multiplication Method (NSM). In this study, MNSM was tested in calculation of subcriticalities and in evaluation of application validity using the educational reactor in Kyung Hee University, AGN-201. For this study, a revised nuclear data library and a neutron transport code system TRANSX - PARTISN were established. Correction factors for various control rod positions were produced using the k-effective values and the corresponding flux distributions and adjoint flux distributions. Experimental values of the core criticality were obtained using the neutron count rates of the BF3 proportional counters. The results showed that the expected reactivity worth of control rods by MNSM agreed well with the theoretical values and the correction factors contributed much for this purpose.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.85-94
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• 1998

Due to relatively high permittivity of water in soils, we placed the soil condenser into soils to measure the soil moisture content. The soil condenser was made with two insulated iron sticks. The capacitance of the soil condenser was determined by the pulse period from RC type oscillation circuit and the highest voltage output accepting 10MHz pulse. After zero point adjustment, the measured relative capacitance percentage (RCS) to the standard condenser obtained by the oscillation circuit almost linearly correlated with the end depth of the sensor submerged in water. The RC type oscillation was disturbed by many sensor installed in a close distance in one place, presumably resulting in that the sensor sticks played as a interfering antennas generating or accepting electron waves from them. The temperature dependance of the output from the sensors could be corrected through experimentally determined revision function. Although lineal correlation was found between soil moisture and RCS, users should derive their own correlation function for every sensor to measure soil moisture, because the outputs were influenced by the installation depth and layout in the soil. The voltage type sensor responded inversely with soil moisture content and so was not suitable to the accurate measurement of soil moisture, but allows high economic benefit in various application such as simplified measurement of soil moisture and irrigation line control because of its low component count. The voltage type moisture sensor could be reinforced by relay controlling circuit to open and to close the solenoid valves respectively at optimal limits of the least and the most soil moisture according to user's adjustment.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.74-78
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• 2003

Multi-channel images of 11-MUA and 11-MUOH self-assembled monolayers were obtained by using two-dimensional surface plasmon resonance (SPR) absorption. Patterning process was simplified by exploiting direct photo-oxidation of thiol bonding (photolysis) instead of conventional photolithography. Sharper images were resolved by using a white light source in combination with a narrow bandpass filter in the visible region, minimizing the diffraction patterns on the images. The line profile calibration of the image contrast caused by different resonance conditions at each points on the sensor surface (at a fixed incident angle) enables us to discriminate the monolayer thickness in sub-nanometer scale. Furthermore, there is no signal degradation such as photo bleaching or quenching which are common in the detection methods based on the fluorescence.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.190-199
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• 2001

In this paper, we have researched the depth of focus (DOF) and cutoff intensity of the $0.1{\mu}m$rule dense line'||'&'||'space pattern according to the various off-axis illumination (OAl) conditions in the optical system of 0.65 NA using ArF excimer laser (193 nm). We have also studied the variation of the DOF and cutoff intensity according to the sub-resolution pattern (hammer head type) size for optical proximity correction (OPC) applied to the capacitor pattern and the various OAl conditions in the same optical system. As a result, it is revealed that the cross type quadrupole or annular illumination is preferred to the conventional X type quadrupole for printing the $0.1{\mu}m$ rule dense pattern. Also, we can investigate the optimal illumination condition and the size of ope sub-resolution pattern to keep a consistent DGF and cutoff intensity trends.