• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.04a
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• pp.45-47
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• 2001

Due to pressure from threatened legislation in Europe, consumer and governmental pressure in Japan, and glob머 market considerations in the US, there is a rapidly growing interest in lead-free solderinger, Although the move to lead free soldering seems inevitable, many problems will arise in production assembly. It is generally acknowledged that the lead-free solders available offer a much s smaller process window than lead/tin, related mainly to the higher soldering temperatures which naturally result from increases of liquidus temperatures of at least 300 C. However, raising reflow temperatures from the current 220-2300 C to 250 2600 C will lead to problems with the boards and components as well as i increasing oxidation effects. There is a need to keep reflow temperatures low without reducing solderablity. Some results on benefits of inert atmospheres are discussed in this paper. For example, testing in a nitrogen atmosphere, with 300 ppm oxygen, by the N National Physical Laboratory (NPU has revealed clear benefits for ine$\pi$mg lead-free alloys, by restoring the solderability to lead/tin levels, by enabling lower soldering temperatures. However, there has been little testing over a range of oxygen levels in nitrogen and this is an important issue in determining n nitrogen supply and oven costs. Some results are reported here from work by NPL conducted for BOC in w which solderability was evaluated for tin기ead and tin/silver/copper eutectic a alloys in a wetting balance over a range of oxygen levels form 10 ppm to 21% ( (air). The studies confirm that acceptable wetting times occur in inert atmospheres a at soldering temperatures 20 to 300 C lower than are possible in air.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.175-185
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• 1998

In this paper, we studied some design methodologies of typical FIR filters based on the peak-error constrained least square criterion which was first introducedd by Adams in 1991. This method is a mixed type of the classical least squared error method(LSM) and the so-called min-max error method (MMM). And by considering both the least squared error as well as the maximum error, the solution, i.e. the impulse response of the filter, can be found only when the restrictions on maximum gain, transition bandwidth, and the squared error are satisfied simultaneously under some trade-off conditions. We used the multiple exchange algorithms for optimization procedure and applied the design methodology to the cases of the multiband filter, the differentiator, and the Hilbert transformer by taking the balance of two design criteria into account. The results show that the peak-error constrained least weighted square error design method(PLEM) is superior in performance to the existing LSM and MMM from both the squared error and the maximum error standpoints. And it is verified that PLEM can be applied to not only the case of simple low pass filter, but also to various types of FIR filters.

• International Journal of Railway
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• v.2 no.3
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.13-20
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• 2014

The natural convection heat transfers of a helical coil in a duct were measured experimentally varying the inclination. To achieve high Rayleigh number, mass transfer experiments instead of heat transfer experiments were performed based upon the analogy. The $Ra_D$ was fixed to $4.55{\times}10^6$. The turn numbers were 1~10. the pitch to diameter ratio were 1.3~5, and the inclination of the helical coil $0^{\circ}{\sim}90^{\circ}$. The measured $Nu_D$ for a single turn of the helical coil was very close to that from McAdams heat transfer correlation for a horizontal cylinder. The heat transfers of the helical coil were varied by the pith, number of turns, and duct height in a complex manner showing the velocity, chimney, and pre-heating effects. The results of the study contributes to the phenomenological analyses of the natural convection heat transfer of a compact heat exchanger.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.193-200
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• 2009

This paper investigated the drop characteristics of oleo pneumatic type landing gear for small aircraft and the effects of cavitations in modeling the landing gear system. The landing gear system employed a simple oleo pneumatic type damper without a metering pin. In general, oleo-pneumatic type landing gears are light-weighted because of it's simplicity, yet they offer excellent impact absorption characteristics. In this study, the landing gear system was modeled using MSC ADAMS, which offers a drop simulation module. After modeling the system, a series of testing was conducted, using a prototype landing gear system, to validate the analysis model and simulation results. The effect of cavitation was considered in the simulation model to obtain a better correlation between the test and simulation results. The results show that adding the cavitation effect in the simulation model significantly improved the simulation model and better captured the dynamic behaviors of the landing system. Using the 'cavitation' model, dynamics characteristics of the landing gear were further evaluated for other landing conditions, such as landing in various angles of slopes.

• Journal of Preventive Medicine and Public Health
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• v.46 no.sup1
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• pp.28-34
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• 2013

Physical activity (PA) professionals and participants recognize enhanced quality of life (QoL) as a benefit of and motivator for PA. However, QoL measures are often problematic and rarely consider the participants' perspective. This paper focuses on recent findings from a larger project on the role of QoL in PA and health promotion. More specifically, we focus on the views of participants and potential participants to better understand the relationship of PA and QoL. In earlier stages of the project we began with a conceptual model of QoL and developed a survey. We now focus on participants' views and ask two questions: 1) what is QoL? and 2) how does PA relate to QoL? We first asked those questions of a large sample of university students and community participants as open-ended survey items, and then asked focus groups of community participants. Overall, participants' responses reflected the multidimensional, integrative QoL model, but the responses and patterns provided information that may not be picked up with typical survey measures. Findings suggest that PA contributes to multiple aspects of QoL, that social and emotional benefits are primary motivators and outcomes for participants, and that the meaning of QoL and PA benefits is subjective and contextualized, varying across individuals and settings. Programs that directly target and highlight the multiple dimensions and integrative QoL, while considering the individual participants and contexts, may enhance both PA motivation and participants' health and QoL.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.94-101
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• 2019

The dynamic characteristics of the composite reflector panels are numerically and experimentally investigated. A dynamics model of the panel is analytically developed based on a deployment mechanism of the antenna. The deployment is passively activated using elastic energy of a spring with two rotational degrees of freedom. Using the flexible multi-body dynamic analysis ADAMS, dynamic behavior of the panels such as velocities, deformations, as well as reaction forces during the deployment, are investigated in the gravity and zero-gravity cases. The reflector panel is manufactured using carbon fiber reinforced plastics (CFRPs) and its deployment characteristics are experimentally observed using a zero-gravity deployment test. The impact response and vibration problems that occur during deployment of the antenna panel have been identified and reliably deployed using dampers.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.2
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• pp.135-143
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• 2016

In this study, an embedded system composed of equipment setting, block importing, scenario setting and output reporting is developed in multi-body dynamics program, ADAMS, for conducting dynamic structural analysis of block lifting process. First, equipment used for block lifting process is set in the simulation environment and the shapes and functions of two lifting beams, and six block loaders are provided as the equipment. Second, the modal analysis result of the lifting block is imported from the static structural analysis system, NASTRAN. Third, the lifting scenarios, such as hoisting, waiting, trolley moving, and wire connecting, are set in the system. Finally, output results in the forms of plots, texts and tables, are reported after the dynamic structural analysis. The test examples conducted in a shipyard are applied into the developed system in various condition and scenarios. The loads at the lug points, the stress contours, and the hot spot tables of the developed system are compared with the result of the static analysis system.

• PNF and Movement
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• v.1 no.1
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• pp.43-57
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• 2003

목적: 병원치료가 필요하지 않을 만큼의 경부통증/증상과 관절가동범위, 경흉추의 다각적 면에서 관계를 조사하기 위해서이다. 방법: 연령은 19세에서 42세(평균연령 28세로 실험에 참여하기를 원하는 건강한 성인 40명을 대상으로 하였다. 경흉추의 척추 자세, 경추 능동 관절 가동범위, 경부 분절 길이 등의 다각적인 면을 측정하였다. 모든 측정들은 동일시에 각 대상자에게 서로 다른 측정자에 의해 두 번 실시되었다. 경부 근 지구력은 수정된 Biering-Sorensen 검사법에 의해 측정되었다. 마지막으로 대상자들에게 경부 통증/증상의 재발에 대한 질문을 하였다. 결과: 14명의 대상자들은 경미한 재발성 경부 통증/증상을 보고하였다. 경부 근 지구력 시간(F(1,38)=6.75, p=0.01)과 좌측 회전 가동 범위(F(1,38)=4.56, p=0.04)가 경부 통증을 가진 대상자들에서 유의하게 감소하였다. 신전 가동범위가 재 측정에서 특정군 변화 즉, 정상군 증가, 경부 통증/증상군 감소(F(1,38)=4.67, p=0.04)가 보였다. 경부 통증/증상군은 정상군과 비교 시 후인 가동 범위의 증가하였다(F(1,38) =4.56, p=0.04). 통증 유무에 관계없이 모든 대상자들에서 우측 회전보다 좌측 회전에서 가동범위가 더 크게 나타났고(F(1,38) =4.34, p=0.04), 반복 측정에서 좌측 측방굴곡 (F(1,38) =5.10, p=0.03)과 우측 측방 굴곡(F(1,38) = 5.27, p=0.03)의 감소가 나타났다. 결론: 경미한 증상의 경부통증 대상자군과 정상적인 대상자군을 비교할 때 그룹 간 차이는 경부 근 지구력 시간의 감소, 좌측 회전 가동 범위 감소와 특히, 두 번 째 측정에서 신전범위 감소가 나타났으나 후인의 가동범위는 증가로 관찰되었다. 이러한 결과들은 경부 통증의 발생과 관련된 초기 가동범위 변화를 제안한다.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.508-519
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• 2021

The purpose of this study was to develop an ICT education program using films to understand and expand of the Interpersonal Caring Theory (ICT). The study was conducted from February 2020 to October 2020. The films were selected by analyzing 10 elements of ICT and the program was developed according to Kolb's Experience Learning Model. 11 experienced nurses participated in the pilot operation of the program and evaluated the validity of the films as experts. The films selected for the ICT education program included The Blind Side (Noticing), Babette's Feast (Participation), Good Will Hunting (Sharing), The King's Speech (Active-listening), The Cure (Companioning), Mr. Holland's Opus (Complimenting), Patch Adams (Comforting), The Shawshank Redemption (Hoping), Mission (Forgiving), The Throne (Accepting). The program consisted of a total of 12 sessions, and each session included discussion questions for the steps of the Experimental Learning Model. After the program was piloted, it was found that the selected films were considered appropriate (I-CVI=0.98) as a result of evaluating the feasibility of films selection according to ICT elements. The developed ICT education program using films can be used to enhance caring competencies of nurses and nursing college students.