• 한국건축시공학회지
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• 제15권4호
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• pp.397-404
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• 2015

국내 공공건설사업의 건설기계경비 손료 선정 시 사용되는 건설기계가격표는 급변하는 현실을 제대로 반영하지 못하고 있다. 본 연구에서는 현실이 반영된 기계경비 산정을 위해 "기계장비 시가표준액표"를 활용하여 표준품셈의 건설기계가격이 지속적으로 제 개정될 수 있는 체계화되고 선진화된 상시관리시스템의 방안을 개발하여 제시하고, 대표적인 장비에 이를 적용하여 건설기계가격의 변화가 정부예산에 미치는 영향을 분석하였다. 본 연구의 결과는 투명하고 공정한 공사비 산정기준을 정립하는 데 도움이 될 것으로 기대한다.

• 한국건설관리학회논문집
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• 제10권5호
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• pp.85-94
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• 2009

최근 국내의 건설회사는 건설경기 침체와 국제금융시장의 연이은 악재로 인해 많은 어려움을 호소하고 있어, 보다 더 세계화되고 국제 경쟁력을 갖춘 건설생산체계를 요구하고 있는 실정이다. 과거 우리나라 건설산업의 선진화 도구로 건설사업관리(CM) 제도가 도입되었다. 하지만, 전 방위적인 노력에도 불구하고 용역형 건설사업관리(CM for Fee)에 국한된 모습을 보이고 있다. 이에 따라 발주방식의 다양성이 요구되고 책임형 건설사업관리(CM at Risk) 발주방식의 도입 필요성이 제기되고 있다. 따라서 본 연구에서는 책임형 건설사업관리 발주방식의 수행 가능성이 높은 대형건설회사를 대상으로 경험과 지식수준, 건설사업관리 세부업무의 중요도 및 현재 역량과 미래 요구 역량수준을 각각 건축분야와 토목분야로 나누어 분석하였고, 이에 따른 역량 강화를 위한 항목을 도출하였다.

• Transactions on Electrical and Electronic Materials
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• 제6권2호
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• pp.73-77
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• 2005

In this study, we investigated response characteristics of liquid crystal display (LCD) with different operating mode of nematic liquid crystals (NLCs) such as 45 $^{circ} twisted nematic (TN), 67.3 $^{circ} TN and electrical controlled birefringence (ECB) on the rubbed polyimide (PI) surface with side chains. The pretilt angles generated on polyimide surfaces of the three kinds of LCD operating modes were about 12 $^{circ} that was higher than those of conventional TN-LCOs. Also, the Electro-optical (EO) performance of these LCOs showed stable condition. Low transmittance of the 45 $^{circ} TN and 67.3 $^{circ} TN cell on the rubbed PI surface were measured by using low cell gap d. The fast response time in ECB cell among the three kinds of LCD operating modes was achieved. Also, thermal ability of fast 90 $^{circ} TN-LCD was investigated. The threshold voltage and the response time of thermal stressed TN-LCOs showed the same performances on no thermal stressed TN-LCOs. There was little change of value in these TN cells. However, the transmittances of TN-LCOs on the rubbed PI surface decreased while increasing thermal stress time. Therefore, the thermal stability of TN-LCD was decreased by the high thermal stress for the long duration.

• 디자인학연구
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• 제17권4호
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• pp.51-60
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• 2004

대표적인 고부가가치 산업의 하나인 의료기기 산업은 선진국과의 기술격차를 최소화하여 해외수출시장의 진입이 매우 용이한 분야임에도 불구하고 그동안 일반인에게는 생소한 분야로 인식되어 각종 제도와 정책적인 지원 등에서 소외받아왔다. 특히 효율적인 진료와 환자의 심리적 안정을 위해 의료기기의 제품디자인은 매우 중요한 요소임에도 불구하고 디자인에 대한 무관심과 인식부족으로 투자와 지원이 부족했었던 대표적인 분야이다. 따라서 본 연구는 국내 의료기기 산업의 현황과 국내외 시장환경에 대한 일반적인 고찰과 함께 현 단계에서의 디자인문제점을 제시하고 이를 해결할 하나의 대안으로 대표적 고부가가치 장비인 이동형 영상진단장비에 대한 디자인개발 프로세스를 진행하여 결과물을 도출하였으며 이를 통한 디자인경쟁력의 중요성을 부각시키고 의료기기산업의 후발 디자인추진업체에 하나의 기초자료와 모델을 제시하고 지속적인 디자인투자의욕을 고취시키는 역할을 하고자 한다.

• Transactions on Electrical and Electronic Materials
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• 제5권1호
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• pp.1-6
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• 2004

Zinc sulfide is a semiconductor with wide band gap and high refractive index and hence promising material to be used as ARC on commercial silicon solar cells. Uniform deposition of zinc sulfide (ZnS) by using chemical bath deposition (CBD) method over a large area of silicon surface is an emerging field of research because ZnS film can be used as a low cost antireflection coating (ARC). The main problem of the CBD bath process is the huge amount of precipitation that occurs during heterogeneous reaction leading to hamper the rate of deposition as well as uniformity and chemical stoichiometry of deposited film. Molar concentration of thiorea plays an important role in varying the percentage of reflectance and refractive index of as-deposited CBD ZnS film. Desirable rate of film deposition (19.6 ${\AA}$ / min), film uniformity (Std. dev. < 1.8), high value of refractive index (2.35), low reflectance (0.655) have been achieved with proper optimization of ZnS bath. Decrease in refractive index of CBD ZnS film due to high temperature treatment in air ambiance has been pointed out in this paper. Solar cells of conversion efficiency 13.8 ％ have been successfully achieved with a large area (103 mm ${\times}$ 103 mm) mono-crystalline silicon wafers by using CBD ZnS antireflection coating in this modified approach.

• 한국전기전자재료학회논문지
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• 제29권6호
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• pp.337-341
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• 2016

In this study, $ Ni_{0.79}(Mn_{2.21-x}Cu_x)O_4$ (x=0~0.25) specimens were prepared by using a conventional mixed oxide method. All specimens were sintered in air at $1,200^{\circ}C$ for 12 h and cooled at a rate of $2^{\circ}C/min$ to $800^{\circ}C$, subsequently quenching to room temperature. We investigated the structural and electrical properties of $ Ni_{0.79}(Mn_{2.21-x}Cu_x)O_4$ specimens with variation of CuO amount for the application of NTC thermistors. As results of X-ray diffraction patterns, all specimens showed the formation of a complete solid solution with cubic spinel phase. The relationship between ln ${\rho}$ and the reciprocal of absolute temperature(1/T) for the NTC thermistors was shown linearity, which exhibited the typical NTC thermistor properties. With increasing the amount of CuO, resistivity at room temperature, B-value, and temperature coefficient resistance decreased.

• 한국전기전자재료학회논문지
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• 제31권6호
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• pp.403-407
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• 2018

In this study, double layer KTN/STO thin films were fabricated on $Pt/Ti/SiO_2/Si$ substrate, their structural and electrical properties were measured according with the number of STO coatings, and their applicability to microwave materials was investigated. The average grain size was about 80~90 nm, the average thickness of the 6-coated KTN thin film was about 320 nm, and the average thickness of the STO thin film coated once was about 45~50 nm. The dielectric constant decreased with increasing frequency, and as the number of STO coatings increased, the rate of change of the dielectric constant with the applied electric field decreased. The tunability of the KTN thin film showed a maximum value of 19.8% at 3 V. The figure of merit of the KTN/1STO thin film was 9.8 at 3 V.

• 한국건축시공학회지
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• 제3권2호
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• pp.129-134
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• 2003

In this research, we used fly-ash and blast-furnace slag as substitute material of cement and fine aggregate, and we, through experiments, researched and analyzed the features of high-flowable concrete added high efficiency AE water reduction agent. The results are below. 1. Liquefaction generally presented high-slump flow value; on the other hand, partial segregation was observed in case of mixing proportion with 65 cm slump flow and above. This segregation was partially improved in accordance with mixing admixture. 2. Compressive strength according to mixing admixture and increasing mixing ratio of fly-ash were subject to be declined when it was initially cast-in, but its gap was improved when time was fully passed. 3. After mixing blast-furnace slag and fly-ash as substitute material, the result showed that the modulus of elasticity against freezing & melting was improved according to mixing blast-furnace slag and also increased in accordance with increasing pulverulent-body volume. 4. According to increasing the mixing volume of fly-ash, the durability factor was deteriorated because compressive strength became lower as well as air content was decreased when it was initially case-in. 5. The minimum air content to secure durability was 3.7%, for that reason, we had better secure admixture such as air entraining agent when cast-in high-flowable concrete.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.789-801
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• 1995

Canals with artificially made internal resorption were filled with 4 techniques(Lateral condensation, Ultrafil, Obtura II, Thermafil) to compare the efficacy of canal filling according to the filling techniques. After canal filling, radiographic examination, dye penetration through the apical portion and percentage of G-P filled area on the internal resorption area were evaluated. To examine the degree of crystal-like structure and the interface between filled G-P and canal wall, SM and SEM images were taken too. The results were as follows : 1. There was no statistically significant difference in apical microleakage among the 4 root canal filling techniques. 2. As a result of radiographic examination, Ultrafil was the best and Obtura II was acceptable but Lateral condensation and Thermafil showed unfavorable canal filling pattern similarly. 3. Ultrafil filled most of artificially made internal resorption area and Obtura II, Lateral condensation, Thermafil in that order filled unfavorably. 4. Degree of crystal like structure was the highest in the group filled with Ultrafil and those of Obtura II and Thermafil were similar and that of gutta percha used in Lateral condensation showed the lowest value. 5. Penetration of gutta percha into the dentinal tubules couldn't be seen in all groups. In the contact surface between the filled G-P and the canal wall, Lateral condensation showed relatively close sealing, Obtura II and Thermafil had irregular contact surface and Ultrafil showed regular filling pattern. 6. Contact surface between the core of Thermafil and the gutta percha showed close relationship without gap formation.

• 전기학회논문지
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• 제60권4호
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• pp.801-804
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• 2011

Electrical properties and microstructure were investigated on the effects of $MnO_2$ and the lead-free $(Na_{0.44}K_{0.52}Li_{0.04})(Nb_{0.83}Sb_{0.07}Ta_{0.1})O_3$ ceramics with the addition of $MnO_2$ were fabricated by a conventional mixed oxide method. A gradual change in the crystal and microstructure was observed with the increase of $MnO_2$ addition. For the NKN-LST-xmol%$MnO_2$ sintered at $1100^{\circ}C$, bulk density increased with the addition of $MnO_2$ and showed maximum value at addition 1.0mol% of $MnO_2$. Curie temperature of the NKN-LST ceramics slightly decreased with adding $MnO_2$. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased below 0.25mol% of $MnO_2$ addition, which might be due to the increase in density. The high piezoelectric properties = 145 pC/N, electromechanical coupling factor = 0.421 and dielectric constant = 2883 were obtained for the NKN-LST-0.25mol%$MnO_2$ sintered at $1100^{\circ}C$ for 4h.