• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.417-419
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• 2011

태양전지 모듈은 back sheet, 후면 충진재, 태양전지 cell, 전면 충진재, 전면 보호유리의 구성으로 되어 있다. back sheet는 유리 또는 금속을 사용하는데 사용 재료에 따라 각각 유리봉입방식, 슈퍼스트레이트방식으로 구분된다[1]. 태양전지를 보호하기 위한 충진재는 빛의 투과율 저하가 적은 PVB(Poly Vinyl Butylo)나 내습성이 뛰어난 EVA(Ethylene Vinyl Acetate) 등이 주로 이용된다. 유리봉입방식과 슈퍼스트레이트 방식의 공통점은 모듈 전면에 투과율과 내?충격 강도가 좋은 강화 유리를 사용하는 것이다. 하지만 현재 모듈의 전면 유리는 평탄한 표면 때문에 태양고도가 낮을 때 상대적으로 반사율이 높은 단점을 가지고 있다[2]. 이러한 문제점을 해결하기 위한 방안으로 표면 유리에 요철(anti-glare) 구조를 형성하면 평면 구조의 표면에서 반사되는 태양광이 일부 태양전지 내부로 재입사가 일어나게 되어 표면 반사율이 낮아지게 되고, 이로 인하여 태양전지의 효율이 증가하게 된다. 특히 이러한 효과는 태양고도가 낮아졌을 때 요철(anti-glare) 구조에 의한 반사율의 감소가 증가하기 때문에 평면 구조보다 요철(anti-glare) 구조의 태양전지 모듈 효율이 향상될 것이다. 본 논문에서는 요철(anti-glare) 구조를 만들기 위해서 유리와 평면 구조의 유리에서의 반사율과 투과율을 측정하여 비교 분석하였고, 특히 태양고도의 고도가 변할 때를 비교하기 위하여 반사율 및 투과율을 측정 할 때 입사광의 각도를 변화시켰다. 그리고 태양전지 cell 위에 요철(anti-glare) 구조의 유리와 평명 구조의 유리를 각각 위치시킨 후 태양전지 cell의 효율변화를 확인하였다. 이때 태양전지 cell의 표면은 이방성 식각 용액을 이용하여 역피라미드 구조의 텍스쳐링 태양전지 cell과 평면 구조의 태양전지 cell을 각각 사용하여 비교하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.774-783
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• 2012

In this paper, a periodically corrugated transmission line is proposed. The proposed transmission line can reduce crosstalk between transmission lines. The corrugated transmission line can adjust the amount of inductive coupling and capacitive coupling equally. Thus, the crosstalk is effectively reduced because the inductive coupling and capacitive coupling cancel each other. The corrugated transmission line is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm. The simulated far-end crosstalks of conventional transmission line and corrugated transmission line with a period of A=1 mm have maximum values of -3.6 dB and -22 dB, respectively, up to 30 GHz. Measurement results showed that far-end crosstalks of the conventional and corrugated transmission line have maximum values of -6.3 dB and -20.5 dB, respectively, up to 30 GHz.

• Journal of the Korean Society of Radiology
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• v.6 no.3
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• pp.191-195
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• 2012

This research aims at examining the amount of scattered radiation generated during irradiation by adhering structures with different sizes of aluminum prominence and depression to the inside of a radiotherapy room. The irregular aluminum structures were stuck to the wall of a radiotherapy room, and the scattered radiation generated during irradiation was measured. The sizes of the aluminum prominence and depression were $1.5{\times}1.5$, $3{\times}3$, and $5{\times}5\;cm^2$ with the width of 60 cm and the height of 60 cm. The distance between TLD and the wall of the radiotherapy room to measure scattered radiation was 310 cm, and the used radiation energy was 6 MV and 15 MV generated from a linear accelerator. The research result showed that the irradiation amount at 6 MV was 100, and at 300 cGy the scattered radiation decreased by the installation of the structure with aluminum prominence and depression, but at 200 cGy, only the scattered radiation of the uneven structure of $5{\times}5\;cm^2$ decreased. At 15 MV, the irradiation amount was 200 cGy, and at 300 cGy, the scattered radiation was reduced when the rugged aluminum structure was set up, but at 100 cGy, similar result values were produced regardless of the uneven structure. Consequently, installation of an additional structure with aluminum prominence and depression in the present interior structure can decreased the stochastic effect of the scattered radiation generated from the wall of a radiotherapy room and patients.

• Proceedings of the Optical Society of Korea Conference
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• 1990.07a
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• pp.73-77
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• 1990

홀로그래피 간섭무늬로부터 변형의 요철방향을 구하기 위하여 위상변위방법을 응용하였다. 위상변위법에 의하여 물체파의 위상을 변화시켜 이에따른 홀로그래피 간섭무늬의 이동을 측정하였다. 간섭무늬가 일정지점을 중심으로 좌우로 이동하는 현상으로부터 변형의 요철방향을 파악하고 최대지점의 위치를 구할 수 있었다.

• 대한공업교육학회지
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• v.34 no.2
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• pp.331-345
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• 2009

In this research Sagnac interferometer three different types of mandrel are suggested and this fiber optic sensor is using in monitoring of electric transformer. Vibration characteristics of those mandrels were analyzed and finally more sensitivity mandrel are suggested. Three different mandrels using in fiber optic sensor are hollow cylinder with outer bump, pure hollow cylinder, hollow cylinder with inner bump. Natural frequencies and mode shapes are investigated using finite element method. Mode shape are considered at the frequency range from 2 kHz to 20 kHz. Fundamental dimensions of the hollow cylinder type's mandrel are 30 mm in outer diameter, 50 mm in length, 1 mm in cylinder thickness, $2mm{\times}2mm$ in bump size. Based on the finite element results, when the outer acoustic frequency is near 11 kHz outer bump type and hollow cylinder can get higher sensitivity. Near 17 kHz outer bump and inner bump mandrel can get higher sensitivity. Near 20 kHz hollow cylinder and inner bump mandrel is useful. This results can be applied to design of fiber optic sensor using in monitoring the electrical transformer. Several MHz of outer acoustic frequency can be easily detected using more sensitive mandrel in pursuing expand this technique.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.177-186
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• 2009

Rumble strip was introduced in highway pavement for driver's safety in Korea on 2000. With proving its effectiveness, total length of highway with rumble strip has increased. This research team suggested a modified form of the existing rumble strip, which was placed on new concrete pavement during construction. The modified construction equipment was applied on test section at PyungTeak-Eumsung highway with some performance experiments. Through the equation of stopping sight distance proposed AASHTO, the modified form is safer than the existing one due to 0.65m of extra width. The indoor noise test showed that the modified form $3.5{\sim}9dB(A)$ noisier than the main pavement, which wasn't applied by rumble method. Therefore, it was one of alternatives to prevent sleeping. The modified form made the frequency effected on man's eye. There were no differences of the noise and vibration between modified form and existing one. However, that driver who participated on operating test on that section felt that the former was safer than the latter. It can be concluded that modified form can be applied to the new concrete pavement, that will decrease traffic accident.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.502-502
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• 2013

유기태양전지는 간단한 제작 공정과 저비용 제작이 가능하고 플렉서블 소자를 제작할 수 있는 장점을 가지고 있어서 많은 연구자들이 관심을 가지고 있다. 하지만 현재 유기태양전지의 효율은 낮기 때문에 실리콘 기반이나 화합물 기반의 태양전지에 비해서 효율이 낮은 단점을 가지고 있다. 유기태양전지의 효율을 높이기 위한 다양한 연구들이 활발하게 진행되고 있다. 특히 나노구조를 가지는 광활성층을 사용하여 제작된 고효율 유기태양전지에 대한 연구가 이루어지고 있다. 나노구조를 가지는 유기태양전지는 생성된 엑시톤을 분리시킬 수 있는 계면이 넓어지기 때문에 전하 분리 효율을 높아지게 되고, 고효율의 유기태양전지를 제작할 수 있게 된다. 또한, 넓은 광흡수 스펙트럼을 가지는 양자점을 활용하는 연구도 함께 진행되고 있다. 양자점을 사용하여 유기태양전지의 효율을 높이는 실험이 진행되고 있지만, 실제 효율을 높이는데 많은 어려움을 가지고 있다. 본 연구에서는 고분자점과 양자점이 결합한 나노복합체를 사용하여 요철 구조를 가진 광활성층을 사용한 유기태양전지를 제작하였다. 고분자점과 양자점이 결합한 나노복합체는 물질에 비해서 넓은 광흡수 영역을 가져서 생성된 엑시톤의 양을 늘리는 역할을 한다. 고분자점과 양자점이 결합한 나노복합체로 만든 요철 구조는 평면구조로 제작한 요철 구조에 비해서 계면에서 균일한 적층이 가능한 나노구조가 제작되기 때문에, 계면에서 일어나는 전하 손실을 줄일 수 있다. 고분자점과 양자점이 결합한 나노복합체로 제작된 요철 구조를 사용한 유기태양전지가 기본 소자에 비해서 상당한 효율 향상을 확인하였다. 양자점을 포함한 나노복합체로 제작된 유기 태양전지의 효율증진 메커니즘을 논한다.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.315-323
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• 2010

It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, it measured bending stress of rail according to the rail surface irregularity in the concrete track on the Seoul Metro. In addition, the relationship between rail surface irregularity and bending stress in concrete track is analyzed by results of the field test. Finally, this study clarified the relationship among bending stress(Y) of rail, train speed(U), rail surface irregularity(v, w) in concrete track. The result of this study is able to use the basis data to establishing the periodic replacements criterion of CWR.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.424-432
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• 2018

We herein analyze and study the shielding effectiveness characteristic of an open conveyor-belt-type microwave dryer that is widely used in industry. In particular, the electromagnetic wave leakage problem of the open-type conveyor belt dryer using a general-purpose 2.45-GHz magnetron was improved by applying the corrugated rectangular waveguide. We conducted the electromagnetic simulation of the optimal shielding effectiveness characteristic with regard to the proposed waveguide structure to analyze the attenuation characteristics of the corrugated rectangular waveguide. To verify the shielding effectiveness characteristic of the fabricated corrugated rectangular waveguide by IEEE standard 299, we achieved the shielding effectiveness of more than 30 dB in the practical microwave dryer with the proposed corrugated rectangular waveguide.

• Journal of Conservation Science
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• v.31 no.3
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• pp.267-278
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• 2015

In this study, the elastomer cover, a new contact material, was developed to establish the customized ultrasonic measurement considering surface irregularities of stone cultural heritages. The cover exhibits high elastic force and wear resistance because it has tensile strength of 17MPa and elongation of 625%. In addition, as a result of comparative experiments for the seven types according to transducers and contact materials including the elastomer cover, rock surface irregularities significantly affect attenuation of ultrasonic velocity. The phenomenon was more noticeable in the chiseling finish and indirect transmission measurement rather than the dabbed finish and direct transmission measurement. However, the Type F using the exponential transducer and elastomer cover showed stable P-wave velocity and high amplitude regardless of the surface irregularities. This because the elastomer cover sufficiently sticks to surface irregularities and removes pores between a transducer and a rock specimen. Therefore, the Type F should be used for the ultrasonic measurement of stone cultural heritages with surface irregularities.