• 한국자동차공학회논문집
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• 제20권4호
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• pp.52-59
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• 2012

The subframe has been generally manufactured by using stamped steel material. Recently, automotive designers are considering aluminum as lightweight material. This paper describes the development process of an aluminum subframe which is made by high level vacuum die casting process, which is beneficial for minimizing gas contents and material properties. The weight of manufactured subframe is reduced by 4kg with the comparison of steel subframe. The aluminum subframe is packaged for the current vehicle layout and the imposed requirement is to attain a better structural performance that is evaluated in terms of mounting stiffness, noise and vibration, and endurance performance. The NVH evaluation results show that sound level is decreased by 8dB with the help of high roll-rod mounting stiffness as well as high structural modes.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.275-280
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• 2009

Femtocells are viewed as a promising option for mobile operators to improve coverage and provide high-data-rate services in a cost-effective manner Femtocells can be used to serve indoor users, resulting in a powerful solution for ubiquitous indoor and outdoor coverage. TThe frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) forapplications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. The IEEE 1588 specification provides a low-cost means for clock synchronisation over a broadband Internet connection. The Time of Packet (ToP) specified in IEEE 1588 is able to synchronize distributed clocks with an accuracy of less than one microsecond in packet networks. However, the timing synchronization over packet switched networks is a difficult task because packet networks introduce large and highly variable packet delays. This paper proposes an enhanced filter algorithm to reduce ths packet delay variation effects and maintain ToP slave clock synchronization performance. The results are presented to demonstrate in the intra-networks and show the improved performance case when the efficient ToP filter algorithm is applied.

• 한국전산유체공학회지
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• 제22권1호
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• pp.103-109
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• 2017

The aerodynamic noise reduction of railway traction motor is required to satisfy new enhanced Korean noise regulations for a train. This paper is the study result on a noise reduction of a railway traction motor using Lattice Boltzmann Method(LBM). To verify the reliability of numerical analysis, the noise performance of the base model evaluated using LBM, and calculated result was compared with the experimental data. In addition, main noise sources were selected to design parameters through analyzing the flow field of the base model. Based on the noise sources analysis result, a design improvement model of traction motor for this study was derived to reduce the noise. The performance of a design improvement model was evaluated by applying a validated numerical scheme. As a result, it was confirmed that the noise was reduced due to the suppression of the internal turbulent flow components.

• 한국전산유체공학회지
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• 제18권4호
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• pp.41-46
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• 2013

The selection of the optimal position of the flap was performed in order to improve the aerodynamic performance during the take-off and landing processes of aircraft. For this, the existing airfoils of the main wing and flap are selected as the baseline model and the lift coefficients (cl) according to angle of attacks (AOA) were calculated with the change of the position of flap airfoil. The objective function was defined as the consideration of the maximum cl, lift to drag ratio and cl at certain AOA. Then, at 121 experimental points within $20mm{\times}20mm$ domain, two dimensional flow simulations with Spalart-Allmaras turbulence model were performed concerning the AOA from 0 to 15 degree. If the optimal position was located at the domain boundary, the domain moved to the optimal position. These processes were iterated until the position was included in the inside of the domain. From these processes, the flow separation at low AOA was removed and cl increased linearly comparing with that of the baseline model.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.843-845
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• 2009

A polymeric host for triplet emitters composed of N-alkylcarbazole and tetramethylbenzene units was successfully synthesized. Efficient energy transfer was observed between this polymeric host and green phosphorescent dyes. The device fabricated using 5 wt% green 1 in the polymeric host as the emitting layer showed the best performance. Thin films of this host-guest system, exhibiting clear stripe patterns could be prepared through the LITI process. The patterned films were then used to fabricate electrophosphorescent devices, which show performance characteristics similar to those of spin-coated devices. The new host material is a good candidate to be used in polymer-based full-color electrophosphorescent light-emitting displays.

• 한국응급구조학회지
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• 제23권2호
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• pp.61-73
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• 2019

Purpose: This study aimed to introduce active learning methods, including flipped, case-based, and team-based learning in an electrocardiography (ECG) course and to investigate outcomes and satisfaction with these methods. Methods: To identify the learning effect of active learning, pre-and post-academic self-efficacy was compared between the experimental and control groups. In the experimental group, pre-and post-knowledge and clinical performance regarding ECG were also assessed. In addition, class satisfaction was investigated after application of active learning methods in the experimental group. Data were collected from 84 paramedic students and analyzed using SPSS 22.0 (IBM, Armonk, NY, USA). Results: The experimental group showed significant improvement in post-academic self-efficacy and knowledge. The experimental group also showed high clinical performance (9.83 out of 10 in ECG checking ability and 9.63 out of 10 in ECG reading ability). The mean satisfaction score was 4.23 out of 5 (responses based on a Likert scale) in the experimental group. Conclusion: Active learning in an ECG course was found to be highly effective and satisfactory. Furthermore, paramedic students can enhance their accountability and judgement with team-based learning through free engagement in discussion.

• 한국추진공학회지
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• 제25권4호
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• pp.19-27
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• 2021

한국형발사체용 연소기 성능 고도화를 위한 핵심기술을 검증하기 위해 고압 축소형 연소기를 개발하였다. 성능 고도화를 위한 핵심기술은 고압 연소기용 분사기 설계, 적층제조기법을 적용한 연소안정화 장치 개발, 고압 축소형 연소기 헤드 및 재생냉각 연소실 설계/제작 등이다. 고압 축소형 연소기 개발을 통해 핵심기술을 검증하였고, 이 기술들은 향후 대형 액체로켓엔진 연소기 개발에 활용될 예정이다.

• 융합정보논문지
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• 제8권2호
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• pp.105-112
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• 2018

본 연구는 중소기업의 팀 리더십행동이 팀워크와 직무만족 간의 관계규명을 검증하는데 목적이 있다. 본 연구를 위해 수도권에 위치한 중소기업 종업원 158명을 대상으로 설문조사한 자료를 구조방정식모형으로 분석하였다. 연구결과는 다음과 같다. 팀 리더십행동은 팀워크에 유의한 영향을 미치는 것으로 나타났다. 팀워크는 직무만족에 긍정적인 영향을 미치는 것으로 확인되었다. 팀워크는 팀 리더십행동과 직무만족 간의 관계를 유의하게 매개효과가 있는 것으로 나타났다. 따라서 본 연구는 중소기업의 전략에 맞게 팀 리더십행동 및 팀워크 역량을 함양함으로써 경쟁력을 강화하고, 팀 리더십행동을 활성화하기 위한 방안을 규명하였다. 또한 중소기업에서 성과를 향상하기 위한 팀 리더십 역량의 개발과 전략 수립 및 운영에 기여할 수 있다.

• Journal of Information Technology Applications and Management
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• 제28권3호
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• pp.31-48
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• 2021

Knowledge is a key resource for organizations to gain and maintain competitive advantage. Therefore, it is important for organizations to motivate employees to share knowledge with each other in order to achieve optimal performance of knowledge resources. Despite the efforts of organizations to share knowledge, knowledge hiding is still prevalent among employees. In this paper, we want to analyze the factors that may cause more general and pervasive knowledge-hiding behavior in organizations through empirical analysis. The results of this study show that, first, the relationship between team cohesion and knowledge hiding has been verified differently depending on the sub-behavior of knowledge hiding : playing dumb, evasive hiding, and rationalized hiding. Team cohesion has been shown to significantly reduce the playing dumb and evasive hiding. On the other hand, it was shown that team cohesion did not have a significant causal relationship with rationalized hiding. Second, the moderating effect of ethical leadership has been statistically significant in terms of team cohesion and relationships with playing dumb and evasive hiding. In other words, the higher the ethical leadership, the stronger the negative relationship between team cohesion and knowledge hiding. Finally, the theoretical and practical implications of this paper and future research directions are discussed.

• 기술혁신학회지
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• 제15권2호
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• pp.421-442
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• 2012

프로젝트 성과에 중요한 영향을 미치는 관리방식과 프로젝트 성과간의 관계에 대해서는 지금까지 지속적으로 연구가 진행되고 있다. 최근의 연구들은 프로젝트의 특성에 따라 프로젝트 관리 방식이 달라져야 하며, 프로젝트 관리방식과 프로젝트 성과간의 관계도 프로젝트 특성에 따라 상이할 수 있음을 주장한다. 그럼에도 불구하고 프로젝트 특성이 프로젝트 관리방식과 프로젝트 성과간의 관계에 어떠한 영향을 미치는가에 대한 연구는 부족한 편이다. 본 연구에서는 프로젝트 관리방식들(팀 자율성, 내부/외부 커뮤니케이션, 개인주의 지향성)이 프로젝트 특성인 프로젝트의 신규성 정도에 따라 프로젝트 성과에 미치는 효과를 분석하였다. 실증분석은 과학기술계 정부출연연구소에 속한 78개 R&D 프로젝트팀을 대상으로 하였다. 분석결과 프로젝트의 신규성 정도가 높을수록 팀 자율성은 프로젝트 성과에 더욱 긍정적인 관계를 보였다. 또한 프로젝트의 신규성 정도가 높을수록 내부 커뮤니케이션은 성과에 더욱 긍정적이지만 외부 커뮤니케이션은 더욱 부정적으로 나타났다.