• 대한간호학회지
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• 제35권7호
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• pp.1229-1237
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• 2005

Purpose: The purpose of this research was to address the working conditions of home health nurses through a nationwide home health agency survey conducted at hospitals. Method: The mail surveys were sent to 303 home health nurses nation wide and returned with a response rate of $71.8\%$. Result: (a) Seventy-five percent of home health agencies were established within the past5 years and half of home health nurses are over 40 years old. (b) Working conditions were considered as follows: Seventy-one percent of respondents were full-time employees, sixty-sixpercent of home health nurses had unscheduled visits on a regular day of duty and forty-eight percent were on vacation. Fifty-one percent of home health nurses have experienced traffic accidents and paid. penalties ($65.9\%$). Self-reported monthly income level per year was an average of 28,364,000 won. (c) Rates were significantly higher for shoulder pain ($61.5\%$), lower back pain ($54.1\%$), knee pain ($39.4\%$), and gastrointestinal problems ($33.0\%$). Conclusion: These baseline results show the importance of improving home health nursing working conditions, a comprehensive prevention system and safeguards from physical discomfort.

• 문화기술의 융합
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• 제6권1호
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• pp.495-500
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• 2020

자동차를 기반으로 하는 애드 혹 네트워크 중 하나인 Vehicular Ad Hoc Network(VANET)은 자율 주행차와 커넥티드 카 등의 기술 개발과 더불어 많은 연구가 진행 중인 주제 중 하나이다. VANET을 구현하는 경우 기존의 TCP/IP를 이용한 연구도 진행하고 있지만, Content Centric Networking (CCN)을 이용한 VANET over CCN (VCCN) 관련 연구도 다양한 장점으로 인해 높은 실현 가능성을 보여주고 있다. 본 논문은 CCN 노드들이 관리하는 전송관련 정보 테이블 중에서 Content Store(CS)에 할당된 공간이 모두 사용되어 새로운 항목을 추가할 경우 기존의 일부 항목을 교체하는 경우에 사용되는 다양한 교체 알고리즘의 성능을 평가하고 특정 네트워크 상황에서의 전송특성을 분석하였다. 모의실험 결과, LRU 교체 알고리즘의 성능이 다른 세 가지 교체 알고리즘 보다 우수하였다. 또한 CS 의 크기가 작더라도 전송 성능이 일정 수준을 유지하였으며, CS의 크기가 클수록 전송 성능은 그에 비례하여 상승하였다. 네트워크가 혼잡한 경우 또는 전송 노드 사이의 거리가 먼 경우 데이터 전송 성능도 감소하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제10권3호
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• pp.26-34
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• 2018

In this paper, we propose a scheduling scheme that can efficiently serve I/O requests having deadlines in flash storage. The I/O requests with deadlines, namely, real-time requests, are assumed to be issued for streaming services of continuous media. Since a Web-based streaming server commonly supports downloads of HTMLs or images, we also aim to quickly process non-real-time I/O requests, together with real-time ones. For this purpose, we adopt the well-known rate-reservation EDF (RR-EDF) algorithm for determining scheduling priorities among mixed I/O requests. In fact, for the use of an EDF-style algorithm, overhead of task's switching should be low and predictable, as with its application of CPU scheduling. In other words, the EDF algorithm is inherently unsuitable for scheduling I/O requests in HDD storage because of highly varying latency times of HDD. Unlike HDD, time for reading a block in flash storage is almost uniform with respect to its physical location. This is because flash storage has no mechanical component, differently from HDD. By capitalizing on this uniform block read time, we compute bandwidth utilization rates of real-time requests from streams. Then, the RR-EDF algorithm is applied for determining how much storage bandwidth can be assigned to non-real-time requests, while meeting deadlines of real-time requests. From this, we can improve the service times of non-real-time requests, which are issued for downloads of static files. Because the proposed scheme can expand flexibly the scheduling periods of streams, it can provide a full usage of slack times, thereby improving the overall throughput of flash storage significantly.

• Smart Structures and Systems
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• 제17권1호
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• pp.91-105
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• 2016

One of the most commonly used techniques to strengthen steel reinforced concrete structures is the application of externally bonded patches in the form of carbon fiber reinforced polymers (CFRP) or recently, textile reinforced cements (TRC). These external patches undertake the tensile stress of bending constraining concrete cracking. Development of full-field inspection methodologies for fracture monitoring are important since the reinforcing layers are not transparent, hindering visual observation of the material condition underneath. In the present study acoustic emission (AE) and digital image correlation (DIC) are applied during four-point bending tests of large beams to follow the damage accumulation. AE helps to determine the onset of fracture as well as the different damage mechanisms through the registered shifts in AE rate, location of active sources and change in waveform parameters. The effect of wave propagation distance, which in large components and in-situ can well mask the original information as emitted by the fracture incidents is also discussed. Simultaneously, crucial information is supplied by DIC concerning the moments of stress release of the patches due to debonding, benchmarking the trends monitored by AE. From the point of view of mechanics, conclusions on the reinforcing contribution of the different repair methodologies are also drawn.

• Macromolecular Research
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• 제11권5호
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• pp.368-374
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• 2003

Porous scaffolds composed of gelatin and polysaccharides such as hyaluronic acid and $\beta$-glucan were prepared by using the freeze-drying method after cross-linking with l-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The scaffold had an inter-connected pore structure with the sufficient pore size for use as a support for the growth of fibroblasts. Results for the contact angle and cell attachment confirmed that high gelatin content in a mixture was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures. However, the addition of polysaccharides aroused the synergistic effects of morphologic and mechanical property of gelatin-based scaffolds. To prepare the artificial dermis for the wound dressing to mimic the normal human dermal skin, fibroblasts were isolated from a child's foreskin, and cultured in gelatin-based scaffolds. An in vivo study showed that the artificial dermis containing the fibroblasts enhanced the wound healing rate and re-epithelialization of a full-thickness skin defect rather than the acellular scaffold after one week.

• 한국통신학회논문지
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• 제40권2호
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• pp.273-284
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• 2015

본 논문에서는 상향링크와 하향링크가 공존하는 역 듀플렉스 셀룰러 네트워크 상황에서 단방향 기지국 협력을 통한 단사 간섭 정렬 타당성에 대한 연구를 하였다. 일반적인 안테나 개수와 사용자수에 따른 단사 간섭 정렬의 필요조건과 충분조건을 제시하였고, 이어서 특정 조건을 만족하는 네트워크에서 간략화 된 충분조건을 제시하였다. 특히 대칭 네트워크 상황에서는 단사 간섭 정렬의 필요충분조건을 제시하였고, 각 셀 당 두 명의 사용자가 존재하는 대칭 네트워크 상황에서는 닫힌 형태의 필요충분조건을 규명하였다. 제안한 단방향 기지국협력을 통해 합 자유도를 크게 증가시킬 수 있으며, 모의실험을 통해 상용 신호 대 잡음비 영역에서 합 전송률을 획기적으로 개선 할 수 있음을 확인 하였다.

• 한국IT서비스학회지
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• 제14권3호
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• pp.183-196
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• 2015

The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. A common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. The IEEE 802.3az Energy Efficient Ethernet (EEE) standard is one of such efforts. EEE introduces a low power mode for the most common Ethernet physical layer standards and is expected to provide large energy savings. However, it has been shown that EEE may not achieve good energy efficiency because mode transition overheads can be significant, leading to almost full energy consumption even at low utilization levels. Coalescing techniques such as packet coalescing and interrupt coalescing were proposed to improve energy efficiency of EEE, but their implementations typically adopt a simple policy that employs a few fixed values for coalescing parameters, thus it is difficult to achieve optimal energy efficiency. The paper proposes adaptive interrupt coalescing (AIC) that adopts an optimal policy that could not only improve energy efficiency but support performance. AIC has been implemented at the sender side with the Intel 82579 network interface card (NIC) and e1000e Linux device driver. The experiments were performed at 100 M bps transfer rate and show that energy efficiency of AIC is improved in most cases despite performance consideration and in the best case can be improved up to 37% compared to that of conventional interrupt coalescing techniques.

• 한국통신학회논문지
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• 제22권8호
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• pp.1774-1781
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• 1997

본 논문은 잔류 측대파(vestigial sideband; VSB) 변조를 이용한 CATV 및 HDTV에서 주파수 및 위상 동기 루프 (frequency & phase lock loop; FPLL)의 완전 디지털 구현을 위한 알고리듬과 하드웨어 구조를 제안한다. 미국의 대연합(Grand-Alliance)에서 제안된 VSB 변조를 위한 CATV 및 HDTV 수신기는 아날로그 신호처리를 통하여 반송파 복구를 수행한다. 그러므로 향후 단열 칩 ASIC 개발에 상당한 부담을 주는 구조이다. 본 논문에서는 VSB 변조 방식의 이러한 문제점을 해결하기 위하여 수신된 신호를 기저 대역 근처의 IF 신호로 떨어뜨린 후 아날로그-디지털(AD) 변환을 통하여 모든 신호처리를 디지털 영역에서 할 수 있는 FPLL 구조를 제안한다. 제안된 시스템은 주파수 풀-인(pull-in) 영역이 -200KHz- +250KHz 정도의 우수한 성능을 보여준다. 그리고 위상 잡음의 영향을 최소화 하면서 빠른 포착 성능을 유지하기 위하여 루프 필터의 대역폭을 적응적으로 가변하는 특징을 가진다.

• 한국지역지리학회지
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• 제7권2호
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• pp.1-16
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• 2001

이 글의 목적은 독일이 당면하고 있는 실업문제와 그 구조적 특성을 살펴보고, 실업이 공간적으로 어떻게 전개되고 있으며 그 원인이 무엇인가를 논의하는데 있다. 독일은 1950년 말이래 안정된 고용체계를 확립하고 완전고용을 성취하였으나, 1970대 중반에 들어서면서 대량실업 사태에 직면하게 되었다. 특히 1990년대에 들어 통일과 함께 구 동독에서 실업률이 높아지면서 불안정한 노동시장이 구조화되고 있으며, 일부 인구집단이 고용체계로의 진입 및 퇴출 과정에서 선별작용을 현저히 겪고 있다. 독일의 실업은 공간적으로 독특한 발전패턴을 보여주고 있는데, 전통적인 남북격차에 동서격차가 겹치는 다중적 양상과 아울러 지리적 권역에 따른 차별적 상황이 부각되고 있다. 특히 전반적인 고실업은 노동시장상의 정책기조의 변화와 통일이라는 시대적 변혁이 맞물려 만성화 내지 장기화되고 있으며, 그 지역적 편차는 노동력 수급에 있어 불균등을 반영하고 있다.

• 한국환경복원기술학회지
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• 제15권1호
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• pp.133-140
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• 2012

The study of Arundinaria munsuensis Y. Lee to this day was limited to the field of morphological species classification since its first discovery at Jiri mountain in the late 1990s. This native plants, one of Korean endemic species found in Jiri Mt. necessitates further studies about its use as revegetation plants or groundcover plants in urban areas. This study was launched from this need followed by summaries of results below related to its usage. This targeted species is a native Korean species which its natural distribution on the subalpine zone has merit for the wide range of climatic adaptation. Also, the coverage rate reached 78.3% in three years mostly by rhizome growth with an expectation of full coverage in four years providing less maintenance needs after planting. The net price for the construction of pot seedling methods of this plants is relatively economical than other normal revegetation construction methods. For these reasons, drilling for the plants on cut and fill soil slopes driven from pot seedling adapts Arundinaria munsuensis Y. Lee as efficient revegetation plant. Total construction cost for pot seedling work($30cm{\times}30cm$) of Arundinaria munsuensis was approximately 21,000won which is in reasonable price range when compared to other revegetation construction methods of disturbed slopes. As a native Korean plant, Arundinaria munsuensis has wide range of climatic adaptation with less maintenance requirement after planting. This study may suggest a strong possibility of Arundinaria munsuensis as a pot planting material in sloped area.