• 한국전기전자재료학회논문지
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• 제27권4호
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• pp.209-216
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• 2014

The screen printed technique is one of the electrode forming technologies for crystalline silicon solar cell. It has the advantage that can raise the production efficiency due to simple process. The electrode technology is the core process because the electrode feature is given a substantial factor (for solar cell efficiency). In this paper, we tried to change conditions such as squeegee angle $55{\sim}75^{\circ}$, snap off 0.5~1.75 mm, printing pressure 0.6~0.3 MPa and 1.6~2.0 mm finger spacing. As a result, the screen printing process showed an improved performance with an increased height higher finger height. Optimization of fabrication process has achieved 17.48% efficiency at screen mesh of 1.6 mm finger spacing.

• 한국전기전자재료학회논문지
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• 제27권5호
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• pp.269-275
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• 2014

In this study, chemical bath deposition method was used to grow Zinc sulfide(ZnS) thin films from $NH_3/SC(NH_2)_2/ZnSO_4$ solutions at $90^{\circ}C$. ZnS thin films have been prepared onto ITO glass. The concentrations of $ZnSO_4$ and $NH_3$ were varied while the concentration of Thiourea was fixed in 0.52 M. Structural, optical, electrical characteristic of ZnS thin films were measured. The physical and optical properties of different ZnS thin films were influenced severely by the concentration of the two reacting chemicals. The optimal concentration of $ZnSO_4$ and $NH_3$ was 0.085 M and 1.6 M, respectively.

• 한국전기전자재료학회논문지
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• 제26권2호
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• pp.140-143
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• 2013

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study, the wafers were first texturing by NaOH solution at $80^{\circ}C$ for 35 min. Then the wafers were texturing by $SF_6$ and $O_2$ plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.

• 한국전기전자재료학회논문지
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• 제26권5호
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• pp.410-414
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• 2013

Rapid thermal processing (RTP) abruptly decreases the time required to perform solar cell processes. RTP were used to form emitter of crystalline silicon solar cells. The emitter sheet resistance is studied as a function of time and temperature. The objective of this study is reduction of doping process time with same performance. Emitter difRapid thermal dfusion was carried out by using a spin on doping and a RTP. iffusion was performed in the temperature range of $700{\sim}750^{\circ}C$ for 1m 30s~15 m. Thermal budgets yielded a $50{\Omega}/sq$ emitter using a P509 source. To reduce process time and get high efficiency, rapid thermal diffusion by IR lamp was employed in air atmosphere at $700^{\circ}C$ for 15 m.

• 한국위험물학회지
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• 제6권2호
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• pp.68-76
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• 2018

This study aims to provide a methodological framework to estimate the travel demand of hazardous materials transporting vehicles by link and analyze daily traffic patterns on an expressway to develop safety roadway management strategies. Traffic volume of hazardous material vehicles is counted through the on-site investigation at twenty-five tollgates on the expressway, and their demands by a link are predicted through origin-destination flows estimation. The result shows that the number of the domestic hazardous materials vehicles is approximately 51,207 vehicles per day and it indicates that hazardous materials transport vehicles account for 1.5% of total daily traffic on the internal expressway and 6.2% of total cargo traffic volumes. This study roughly estimated how many hazardous materials vehicles pass through the expressway segment. Thus it is expected to be utilized for establishing a systematic highway management strategy in the future by calculating the traffic volume of the hazardous material vehicles traveling on the interstate expressway.

• 전기화학회지
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• 제22권4호
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• pp.172-176
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• 2019

The first commercialized cathode material, $LiCoO_2$, suffers from disadvantages such as high cost and toxicity and also possesses safety problems. The nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material, used as an alternative to $LiCoO_2$, has highly reversible capacity and high energy density. So, the nickel-rich $LiNi_{0.9}Mn_{0.1}O_2$ cathode material is widely used as an alternative to $LiCoO_2$ due to its highly reversible capacity and high energy density. However, $LiNi_{0.9}Mn_{0.1}O_2$ has several disadvantages as well, such as poor cycle performance and poor thermal instability. To address these problems, we synthesized a new material, $LiNi_{0.5}Mn_{0.5}O_2$, as a shell on the surface of a core to suppress the surface degradation. The new material showed high structural and thermal stabilities and could also maintain a high capacity. The capacity retention of the core-shell cathode (87.7%) was better than that of the core cathode (76.9%) after 50 cycles. Analysis using differential scanning calorimetry revealed that the heat generation in the core-shell cathode ($65.9Jg^{-1}$) was lower than that in the core cathode ($559.7Jg^{-1}$).

• 대한산업공학회지
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• 제34권3호
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• pp.296-307
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• 2008

A semiconductor production system has sophisticated manufacturing operations and needs high capital investment for its expensive equipment, which warrants efficient real-time flow control for wafers. In the bay, we consider material handling equipment that can handle multiple carriers of wafers. The dispatching logic first determines the transportation time of each carrier to its destination by each unit of transportation equipment and uses this information to determine the destination machine and target carrier. When there is no available buffer space at the machine tool, the logic allows carriers to stay at the buffer of a machine tool and determine the delay time, which is used to determine the destination of carriers in URL. A simulation study shows this dispatching logic performs better than the procedure currently in use to reduce the mean flow time and average WIP of wafers and increase efficiency of material handling equipment.

• 한국건설관리학회논문집
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• 제4권4호
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• pp.182-191
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• 2003

초고층$\cdot$대형 현장은 일반 현장관리 방법과는 달리 경험에 의한 의사결정에는 한계가 있다. 특히 도심지 고층 공사의 경우 대지의 여유 공간이 협소하여, 자재적치와 수평 동선을 위한 공간의 확보가 용이하지 않다. 이러한 초대형 프로젝트를 수행하기 위해서는 기존 경험에 의존하는 양중 및 조달 관리의 한계성을 인식하고 새로운 양중 및 조달 관리 방법의 모색이 필요하게 되었다. 따라서 JIT의 개념을 도입하는 것이 필수적이라 하겠다 현장 내 즉, 반입 이후의 단계는 물리적인 자재의 흐름보다는 정보의 흐름과 의사소통이 중요시되는 단계로 본 연구에서는 현장 내 물류흐름의 문제점을 분석하여, 자재별 속성을 고려한 양중계획수립, 작업일정과 양중일정의 통합관리, 자재의 위치현황 및 작업의 설치현황 가시화를 통한 정보의 공유, 계획대비 실적의 평가의 부분을 시스템개발 방향으로 설정하여. 커뮤니케이션 도구로서의 역할과 계획 대비 실적 평가를 통한 계획의 신뢰도 확보 등을 주요 기능으로 하는 양중관리시스템을 개발하였다.

• 대한화학회지
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• 제59권2호
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• pp.142-147
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• 2015

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.

• 한국농공학회논문집
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• 제61권1호
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• pp.85-93
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• 2019

The objective of this study is to assess the environmental effect of the reclaimed land drainage method using oyster shell through the Life cycle $CO_2$ assessment, and to evaluate the applicability in South Korea. In this Study, the life cycle $CO_2$ emissions of oyster shell (OS) and crushed stone (CS, as avoided product) were assessed and compared. The Life Cycle Assessment method was used for quantitative evaluation of direct or indirect environmental effects of OS recycling. $CO_2$ was selected as the evaluation target material, and the scope of assessment includes the acquisition of materials, processing, transportation, construction phases. Compared to using CS, 77.0% of $CO_2$ emissions in acquisition and processing, 47.0% in transportation and 6.5% in construction phase were reduced, respectively by using of OS. The maximum transportation distance of OS was estimated according to transportation distance of CS. OS has environmental advantages than CS within about 26 - 101 km from the source. OS was found to be applicable to reclaimed lands up to 810 ha, 3,910 ha from Tongyeong and Yeosu, respectively. In addition, the amount of OS that could be used as drainage material for reclaimed land was much higher than annual OS production of South Korea. Therefore, it is considered that OS is sufficient to be used as drainage material for reclaimed land in South Korea.