• The Korean Publising Journal, Monthly
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• s.373
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• pp.114-115
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• 2006

• The Korean Publising Journal, Monthly
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• s.370
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• pp.112-113
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• 2006

• The Korean Publising Journal, Monthly
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• s.362
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• pp.120-121
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• 2006

• The Korean Publising Journal, Monthly
• /
• s.360
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• pp.120-121
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• 2005

• The Korean Publising Journal, Monthly
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• s.369
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• pp.112-113
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• 2006

• The Korean Publising Journal, Monthly
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• s.372
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• pp.116-117
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• 2006

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.858-866
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• 2013

In the DVB-S2, which is the technical specification of the second generation digital video broadcasting via satellite, APSK modulation scheme along with LDPC coding schemes are defined. APSK is a multi-lelvel PSK modulation scheme and decoding of LDPC coded signal requires soft decision information. Therefore, the APSK demodulator at the receiver should have capability of estimating soft information. In this paper, we introduce a method to estimate soft information by using simple distance estimation, and show that this method overestimates the soft information. Subsequently, this overestimated soft information leads to performance degradation. In order to overcome this problem, we propose a scaling method to improve the performance at the receiver In addition, we show that the proposed scaling scheme enables us to estimate the soft information with linear order complexity and produce the performance close to the maximum likelihood detection.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.24.1-24.1
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• 2011

CMP (Chemical Mechanical Planarization)는 고직접도의 다층구조의 소자를 형성하기 위한 표면연마 공정으로 사용되며, pattern 크기의 감소에 따른 공정 중요도는 증가하고 있다. 반도체 소자 제조 공정에서는 낮은 비용으로 초기재료를 만들 수 있고 우수한 성능의 전기 절연성질을 가지는 산화막을 만들 수 있는 단결정 실리콘 웨이퍼가 주 재료로 사용되고 있으며, 반도체 공정에서 실리콘 웨이퍼 표면의 거칠기는 후속공정에 매우 큰 영향을 미치므로 CMP 공정을 이용한 평탄화 공정이 필수적이다. 다결정 실리콘 박막은 현재 IC, RCAT (Recess Channel Array Transistor), 3차원 FinFET 제조 공정에서 사용되며 CMP공정을 이용한 표면 거칠기의 최소화에 대한 연구의 필요성이 요구되고 있다. 본 연구에서는 알칼리성 슬러리를 이용한 단결정 및 다결정 실리콘의 식각 및 연마거동에 대한 특성평가를 실시하였다. 화학적 기계적 연마공정에서 슬러리의 pH는 슬러리의 분산성, removal rate 등 결과에 큰 영향을 미치고 연마대상에 따라 pH의 최적조건이 달라지게 된다. 따라서 단결정 및 다결정 실리콘 연마공정의 최적 조건을 확립하기 위해 static etch rate, dynamic etch rate을 측정하였으며 연마공정상의 friction force 및 pad의 온도변화를 관찰한 후 removal rate을 계산하였다. 실험 결과, 단결정 실리콘은 다결정 실리콘보다 static/dynamic etch rate과 removal rate이 높은 것으로 나타났으며 슬러리의 pH에 따른 removal rate의 증가율은 다결정 실리콘이 더 높은 것으로 관찰되었다. 또한 다결정 실리콘 연마공정에서는 friction force 및 pad의 온도가 단결정 실리콘 연마공정에 비해 상대적으로 더 높은 것으로 나타났다. 결과적으로 단결정 실리콘의 연마 공정에서는 화학적 기계적인 거동이 복합적으로 작용하지만 다결정 실리콘의 경우 슬러리를 통한 화학적인 영향보다는 공정변수에 따른 기계적인 영향이 재료 연마율에 큰 영향을 미치는 것으로 확인되었으며, 이를 통한 최적화된 공정개발이 가능할 것으로 예상된다.

• Clean Technology
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• v.20 no.4
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• pp.339-348
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• 2014

Life cycle assessment (LCA) has become an important tool used to enhance the environmental performance of process systems and products. LCA is an essential element in design for environment (DfE) because LCA can be utilized to evaluate and analyze environmental impacts incurred in the life cycle and supply chain. This review presents methodologies that can be used to integrate LCA into DfE activities and reduce environmental impacts from process systems and products; and introduces case studies for water supply systems and cellular phones. LCA is first used to quantify environmental impacts and identify the principal contributor to high impacts. In the next step, environmental impacts from principal contributors can be reduced by using mathematical optimization tools as an engineering and technological approach and by utilizing the cooperation of professionals from a diverse range of fields. Because the methodologies and case studies can be applied and extended to other fields, this review paper can contribute to helping prevent environmental pollution and enhance the sustainability of our society.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2D
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• pp.255-266
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• 2011

In order to evaluate the environmental load occurring from the whole life cycle of a facility, LCA (Life Cycle Assessment) adopted by ISO is not only applied as an individual product but rather a complicated system involving buildings and/or infrastructure in a wide range of scope. The introducing of LCA to a wastewater reuse facility will assist to understand not only the treatment of water contaminants but also the overall system related to the interaction of involved, potential issues. This research implemented LCA for the establishment of the wastewater reuse facility. The results show that a fresh water aquatic Eco-toxicological Impact (88.3%) is the largest environment concern and the maintenance & operation phase has the most impact on the environment utilizing life cycle for the wastewater reuse facility. The civil works and chemical treatments in the maintenance & operation phase led to the biggest environmental impact. The results of this research can provide pertinent data of investigating opportunities for environmental improvement not limited to public officers regulating environmental policies, and could be used to make decisions for an environmentally sound and sustainable design in the initial phase of construction.