• 대한임베디드공학회논문지
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• 제8권4호
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• pp.185-194
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• 2013

Abstract- In distant-talking environments, speech recognition performance degrades significantly due to noise and reverberation. Recent work of Michael L. Selzer shows that in microphone array speech recognition, the word error rate can be significantly reduced by adapting the beamformer weights to generate a sequence of features which maximizes the likelihood of the correct hypothesis. In this approach, called Likelihood Maximizing Beamforming algorithm (Limabeam), one of the method to implement this Limabeam is an UnSupervised Limabeam(USL) that can improve recognition performance in any situation of environment. From our investigation for this USL, we could see that because the performance of optimization depends strongly on the transcription output of the first recognition step, the output become unstable and this may lead lower performance. In order to improve recognition performance of USL, some post-filter techniques can be employed to obtain more correct transcription output of the first step. In this work, as a post-filtering technique for first recognition step of USL, we propose to add a Wiener-Filter combined with Feature Weighted Malahanobis Distance to improve recognition performance. We also suggest an alternative way to implement Limabeam algorithm for Hidden Markov Network (HM-Net) speech recognizer for efficient implementation. Speech recognition experiments performed in real distant-talking environment confirm the efficacy of Limabeam algorithm in HM-Net speech recognition system and also confirm the improved performance by the proposed method.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1475-1482
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• 2006

Wet compression means the injection of water droplets into the compressor of gas turbines. This method decreases the compression work and increases the turbine output by decreasing the compressor exit temperature through the evaporation of water droplets inside the compressor. Researches on wet compression, up to now, have been focused on the thermodynamic analysis of wet compression where the decrease in exit flow temperature and compression work is demonstrated. This paper provides thermodynamic and aerodynamic analysis on wet compression in a centrifugal compressor for a microturbine. The meanline dry compression performance analysis of centrifugal compressor is coupled with the thermodynamic equation of wet compression to get the meanline performance of wet compression. The most influencing parameter in the analysis is the evaporative rate of water droplets. It is found that the impeller exit flow temperature and compression work decreases as the evaporative rate increases. And the exit flow angle decreases as the evaporative rate increases.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.169-171
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• 2012

Although work-efficiency of construction machinery is a critical factor for estimating its workable-quantity per unit time, the coefficient figure table presented in the Poom-Sam that is used for Construction Cost Estimation of public sectors in Korea is very subjective for practical usage. In order to suggest objective work-coefficient table for a Tub Grinder, domestic and overseas documentary records were investigated and on-going construction sites were also visited. The research found that the table can be revised by means of detailing down by several factors. The research will be the foundation for applying the rapid development of Construction Equipment and technology to the appropriate cost estimations and the ground work of related studies.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.181-193
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• 2014

The environment of supply chains is rapidly changed to global and eco-freindly work process. However, at current environment, it is not easy to grasp work flow and to analyze energy efficiency. Improving energy efficiency and visibility for goods flow can contribute to increases in customer attitudes and reductions in overall production costs Additionally, it can lead to increases in work efficiency and reductions in overall production costs. Until recently, efforts to improve energy performance focused on manufacturing industry. Those efforts have expanded to the supply chain. In this paper, we perform business process modeling about supply chain for visibility and sustainability - information and component flows - from assembly plants to logistics. This paper defines the work and information flows by modeling the underlying logical structures of the supply chain and the business processes that determine impact of visibility and sustainability. We model processes using the modeling methodology specified by UN/CEFACT. This methodology explains business process functionality and business transactions by UML diagram. The output of this paper would be useful in grasping work flow and capturing the used energy.

• 대한인간공학회지
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• 제30권3호
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• pp.427-435
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• 2011

Objective: The objective of this study was to evaluate a work of building cleaners using the ergonomic methods. Background: Previous studies about cleaning worker describe typical physical demands of this work. They found that the most significant risk factors associated with the physical work of cleaners are static loads and repetitive movements and high output of force. Method: A head of ergonomics estimation was work analysis(define of combined task, work tool, work time and frequency of combined task) and posture analysis of worker. Results: The results showed that combined task of building cleaners was classification sweeping, mopping(wet), mopping(oil), moving barrels/carts, dumping trash bags, scrubbing, arrangement of cleaning tool, arrangement of circumferential, moving of cleaning tool, and waiting. The work time of combined task such as mopping(wet) and scrubbing indicated high ratio. The posture analysis of building cleaners indicated high value in bending of the head, lower arm, and hands. Conclusion: The findings appear to indicate that building cleaner were related to high risk of work-related musculoskeletal disorders. So, building cleaner would be required an interventional strategy, improvement of cleaning tools and working environment. Application: If ergonomics rule can be integrated into existing cleaning tools and work environments, the risk of occupational injuries will be reduced.

• 한국건설관리학회논문집
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• 제10권4호
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• pp.14-25
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• 2009

공동주택 개발사업은 대규모의 자원과 인력이 투입되는 중장기 복합공정 사업으로 사업 내 외적 영향요인이 복합적으로 관계되는 바, 사업추진 시 현장여건을 비롯한 정치 경제 사회 분야의 내 외부 불확실성 요소로 인한 많은 사업 리스크가 발생하게 된다. 이러한 리스크는 사업의 성패를 결정짓는 중요한 인자로서 작용하게 되며, 종국에 기업의 수익 및 재무구조를 변화시키는 중점 관리요인으로 그 중요성이 크게 대두되고 있어 이에 따른 리스크 저감을 위한 방안 및 효율적인 대책이 필요하다. 이와 같은 관점에서 본 연구에서는 건설프로젝트 중 공동주택 개발사업을 대상으로, VE기반 리스크 관리모델 및 절차를 수립하고 이에 따른 사업 추진 시 기획 및 설계, 시공, 유지관리에 이르는 전 단계에서의 발생 가능한 리스크 요인을 총 3단계 10분류 81개 항목으로 도출, 분석하고, 각각의 리스크 항목별 중요도를 가치공학(VE)을 기반으로 하여 평가 제시함으로써 궁극적으로 개발사업의 성공적인 추진과 이에 따른 공공 및 민간 건설 산업의 경쟁력을 확보할 수 있는 기초자료를 제시하였다.

• 한국건설관리학회논문집
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• 제13권1호
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• pp.44-52
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• 2012

합리적인 방법에 의해 결정된 건설 공사비를 포함하여 계약을 체결하는 것은 공공 건설공사의 사업비 관리 측면에서 매우 중요하다. 국내에서는 건설 공사비를 산정하는 기준으로 표준품셈이 사용되고 있지만, 표준품셈에서 제시하는 품의 적정성에 대해서 문제가 제기되고 있으며, 현장의 자원 투입량과 품셈에서 제시하는 자원 투입량의 차이로 합리적이고 효율적인 공사비를 산정하는데 어려움이 있다. 본 연구에서는 건설 공사비를 합리적으로 산정하기 위하여, 공동주택 거푸집 공사의 생산성 분석을 통한 작업조 기반의 Cost Data Prototype을 제시하였다. 특히, CYCLONE 모델은 민감도 분석을 통해 최적의 작업인원을 제시하는 모델이므로, 거푸집 공사의 다양한 작업공간과 작업인원을 대상으로 생산성을 분석할 수 있는 도구로 활용이 가능하다. 그리고 개발된 회귀식은 거푸집 공사의 작업인원을 독립변수로 하여, 필요한 작업량을 종속변수로 예측하는데 활용이 가능할 것이다.

• 산업융합연구
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• 제21권9호
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• pp.11-21
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• 2023

그동안 CG제작공정의 효율성을 향상시키기 위한 많은 연구가 있었지만, 작업 중간에 결과물의 확인이 어렵고 렌더링 타임에 많은 시간이 소요된다는 문제점을 극복하기는 쉽지 않았다. 그러나 최근 실시간으로 결과물의 확인이 가능한 언리얼 라이브 링크의 활용 가능성이 커지면서 제작공정의 효율성 향상에 대한 기대감이 높아지고 있다. 이에 이 연구에서는 언리얼 라이브 링크를 이용한 3D 애니메이션 제작공정의 효율성을 분석하였다. 이를 위해 마야로 모델링, 리깅, 애니메이션, 레이아웃 작업을 하고 언리얼 라이브 링크를 통해 언리얼 엔진에서 최종 아웃풋 이미지 시퀀스를 도출하는 방식으로 3D 애니메이션을 제작하였다. 그리고 3D 소프트웨어 자체에서 최종 아웃풋 이미지 시퀀스를 을 도출하는 기존의 제작공정과 본 제작공정의 차이점을 비교 분석하였다. 분석 결과 전통적인 3D 애니메이션의 제작공정과 달리 높은 퀄리티의 최종결과물을 보여주는 뷰포트 화면을 통해 작업을 진행함으로써 실시간으로 최종 작업 결과물을 확인하는 것이 가능하였으며, 실시간 화면 캡쳐를 통해 최종결과물을 도출함으로써 작업의 효율성이 극대화되는 것을 알 수 있었다. 최근 3D 애니메이션과 영화 산업현장에서 게임 엔진을 활용하는 사례가 점차 늘고 있는데, 언리얼 라이브 링크를 활용할 경우 작업의 효율성이 매우 극대화될 것으로 예상된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.397-397
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• 2016

Triboelectric nanogenerators (TENG) can produce power from ambient mechanical sources and have strong points of high output performance, light weight, low cost, and easy manufacturing process. It is expected that TENG can be utilized in the fields of wireless electronics and self-powered devices in the world which pays attention to healthcare and the IoT. In this work, we focus on scavenging ambient rotational energy by using a durably designed TENG. In previous studies regarding harvesting rotation mode energy, the devices were based on sliding mechanism and durability was not considered as a major issue. However friction by rotation causes reliability problems due to wear and tear. Therefore, in this study, we convert rotary motion to linear motion utilizing a cam by which we can then utilize contact-mode TENG and improve device reliability. In order to increase output performance, bumper springs were used below the TENG and the optimum value for the bumper spring constant was analyzed theoretically. Furthermore, the inserting a soft substrate was proposed and its effect on high output was determined to be due to an increase in the contact area. By increasing the number of cam noses, the output frequency was shown to increase linearly. For the purpose of maximum power transfer, the input impedance of the device was determined. Finally, to demonstrate the use of the C-TENG as a direct power source, it was installed on a commercial bicycle wheel and connected to 180 LEDs. In conclusion we present a rotational motion TENG energy scavenger system designed for enhanced durability and optimized output by appropriate choice of spring constants and substrate.

• Journal of Biosystems Engineering
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• 제39권4호
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• pp.274-282
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• 2014

Purpose: In this study, a hybrid power system was developed for agricultural machines with a 20-KW output capacity, and it was attached to a multi-purpose cultivator to improve the performance of the cultivator, which was evaluated using output tests. Methods: The hybrid system combined heterogeneous sources: an internal-combustion engine and an electric power motor. In addition, a power splitter was developed to simplify the power transmission structure. The cultivator using the hybrid system was designed to have increased fuel efficiency and output power and reduced exhaust gas emissions, while maintaining the functions of existing cultivators. Results: The fuel consumption for driving the cultivator in the hybrid engine vehicle (HEV) mode was 341 g/KWh, which was 36% less than the consumption in the engine (ENG) mode for the same load. The maximum power take off output of the hybrid power system was 12.7 KW, which was 38% more than the output of the internal-combustion engine. In the HEV mode, harmful exhaust gas emissions were reduced; i.e., CO emissions were reduced by 36~41% and NOx emissions were reduced by 27~51% compared to the corresponding emissions in the ENG mode. Conclusions: The hybrid power system improved the fuel efficiency and reduced exhaust gas emissions in agricultural machinery. Lower exhaust gas emissions of the hybrid system have considerable advantages in closed work environments such as crop production facilities; therefore, agricultural machinery with less exhaust gas emissions should be commercialized. However, the high manufacturing cost and complexity of the proposed system are challenges which need to be solved in the future.