• 제목/요약/키워드: JOA

검색결과 267건 처리시간 0.025초

무선 센서 네트워크에서 효율적인 이미지 전송을 위한 웨이블릿 압축 기법 (Wavelet Compression Technique for Efficient Image Transmission in Wireless Sensor Networks)

  • 권영완;박총명;이좌형;정인범
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2008년도 추계학술발표대회
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    • pp.946-949
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    • 2008
  • 저가형 이미지 센서와 무선 센서 네트워크의 하드웨어 성능 향상으로 인해 WMSN(Wireless Multimedia Sensor Networks) 기술이 주목받고 있다. WMSN은 기존의 무선 센서 네트워크 기술에 멀티미디어 정보를 센싱하고 처리하는 기반기술을 포함한다. 멀티미디어 컨텐츠는 많은 데이터양을 가지므로 이를 처리하기 위해서는 많은 계산량과 데이터 전송량을 필요로 하게 된다. 저사양의 센서 노드에서 이를 수용하기 위해서는 에너지 소모를 고려한 압축 기법 및 효율적인 전송에 대한 연구가 필요하다. 본 논문에서는 무선 센서 네트워크에서 이미지를 효율적으로 압축하고 전송하기 위하여 웨이블릿의 Resolution Scalability 특성을 이용한 4가지 움직임 보상/예측 기법을 제안하고, 압축 성능과 발생 패킷 수, 에너지 소모량을 비교하였다.

센서네트워크에서 노드중심의 다중 이동 노드 위치 인식 기법 (Localization of Multiple Mobile Nodes based on Node Centric Method in Sensor Network)

  • 이좌형;임화정;차영환
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2007년도 추계학술발표대회
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    • pp.1050-1053
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    • 2007
  • 여러 이동노드들이 한 지역에서 동시에 위치인식 작업을 수행하는 경우에 비콘 노드들이 발생시키는 비콘이나 초음파 등이 충돌을 일으킬 수 있다. 본 논문에서는 이동 노드들이 위치확인 작업을 수행하고자 하는 경우에 RTS메시지와 CTS메시지를 이용하여 충돌을 회피하도록 하는 MNC기법을 제안한다. MNC에서는 다른 노드가 위치확인 작업을 수행하는 경우에는 NTS를 전송하여 노드 간에 작업이 충돌되지 않도록 한다. 이동노드가 비콘노드들에 작업순서를 결정하여 STS메시지로 통보하여 비콘노드간에 충돌을 방지한다.

인프라 기반 다중 이동 노드 위치 인식 기법 (Localization of Multiple Mobile Nodes based on Infra Centric Method)

  • 임화정;이좌형;차영환
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2007년도 추계학술발표대회
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    • pp.1054-1057
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    • 2007
  • 여러 이동노드들이 한 지역에서 동시에 위치인식 작업을 수행하는 경우에 노드들이 발생시키는 비콘이나 초음파 등이 충돌을 일으킬 수 있다. 본 논문에서는 이동 노드들이 위치확인 작업을 수행하고자하는 경우에 RTS메시지와 CTS메시지를 이용하여 충돌을 회피하도록 하는 MIC기법을 제안한다. 다른 노드가 위치확인 작업을 수행하는 경우에는 NTS를 전송하여 노드 간에 작업이 충돌되지 않도록 한다.

Can the Zero-Profile Implant Be Used for Anterior Cervical Discectomy and Fusion in Traumatic Subaxial Disc Injury? A Preliminary, Retrospective Study

  • Kim, Tae Hun;Kim, Dae Hyun;Kim, Ki Hong;Kwak, Young Seok;Kwak, Sang Gyu;Choi, Man Kyu
    • Journal of Korean Neurosurgical Society
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    • 제61권5호
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    • pp.574-581
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    • 2018
  • Objective : The zero-profile implant (Zero-P) is accepted for use in anterior cervical fusion for the treatment of degenerative cervical disease. However, evidence pertaining to its efficiency and safety in traumatic cervical injury is largely insufficient. This study aimed to compare the overall outcomes of patients who underwent Zero-P for traumatic cervical disc injury. Methods : Data from a total of 53 consecutive patients who underwent surgery for traumatic or degenerative cervical disc disease using the Zero-P were reviewed. Seventeen patients (group A) had traumatic cervical disc injury and the remaining 36 (group B) had degenerative cervical disc herniation. The fusion and subsidence rates and Cobb angle were measured retrospectively from plain radiographs. The patients' clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score and Odom's criteria. Results : The C2-7 Cobb and operative segmental angles increased by $3.45{\pm}7.61$ and $2.94{\pm}4.59$ in group A; and $2.46{\pm}7.31$ and $2.88{\pm}5.49$ in group B over 12 postoperative months, respectively. The subsidence and fusion rate was 35.0% and 95.0% in group A; and 36.6% and 95.1% in group B, respectively. None of the parameters differed significantly between groups. The clinical outcomes were similar in both groups in terms of increasing the JOA score and producing a grade higher than "good" using Odom's criteria. Conclusion : The application of Zero-P in patients with traumatic cervical disc injury was found to be acceptable when compared with the clinical and radiological outcomes of degenerative cervical spondylosis.

실내환경에서 무선 센서 네트워크구축을 위한 패킷 전송성능평가 (Analysis of Packet Transmission Performance for Construction of Wireless Sensor Networks in Indoor Environment)

  • 이좌형;정인범
    • 한국정보통신학회논문지
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    • 제13권9호
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    • pp.1941-1946
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    • 2009
  • 무선 센서 네트워크는 사람을 대신해 다양한 환경에서 감시와 정보수집 역할을 수행한다. 센서네트워크는 제한된 하드웨어 자원과 낮은 무선 네트워크 대역폭을 사용한다. 이러한 특성은 통신 중 높은 에러율을 발생시키며 데이터 신뢰도 향상을 위한 오류정정 기법의 필요성이 높다. 센서노드의 환경에 따른 CRC 에러와 패턴에 대한 연구는 오류정정 기법의 적절한 기법 선택을 위한 자료가 된다. 본 논문에서는 실내환경에서 시스템 구성시 데이터 전송률에 영향을 미치는 전송주기와 센서 노드간의 거리, 전송 패킷의 크기, RF의 크기에 대한 실험을 실시한다. 실험한 결과를 바탕으로 시스템 구성에서 고려해야 하는 요소를 알아본다.

SS400-STS304 이재용접부의 외력작용시 용접잔류응력 특성 (Influence of Welding Residual Stress on the Mechanical Behavior of Externally Loaded Dissimilar SS400-STS304 Steel Weldment)

  • 방희선;방한서;김유철;주성민;좌순원;노찬승
    • Journal of Welding and Joining
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    • 제27권5호
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    • pp.34-41
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    • 2009
  • Thermal and mechanical characteristics in dissimilar SS400-STS304 steel weldment have been investigated by 3D thermal elastic-plastic analysis. Moreover, the influence of welding residual stresses on the mechanical behaviour of this welded joint, by applying superimposed external load (tension load) was determined. The residual stresses obtained by numerical simulation were compared with the experimentally measured results. The FE results were in good agreement with the measured values. The mechanical test (hardness, tensile test) and metallurgical analysis was carried out to ensure the weld integrity. Hence, possibility of applying SS400-STS304 dissimilar steels in industries has been established.

An NMR Study on Internal Rotation of $CH_3$ Group in 1,1,1-Trichloroethane

  • Hyung Namgoong;Kim, Joa-Jin;Lee, Jo-Woong
    • 한국자기공명학회논문지
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    • 제4권1호
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    • pp.29-40
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    • 2000
  • Coupled carbon-13 relaxation study of 1,1,1-trichloroethane dissolved in DMSO has been performed to gain some crucial insight into the dynamics of methyl group in this compound. For this purpose the relaxation behaviors of several observable magnetization modes for CH3 spin system generated by various perturbing pulse sequences have been carefully investigated and various dipolar spectral densities were estimated by nonlinear numerical fittings of the observed data with the relaxation curves, which were then employed to determine the three principal values for the diffusion tensor for end-over-end molecular rotation as well as internal rotational parameters of methyl group. In this process we could uniquely determine two correlation times $\tau$int(1) and $\tau$int(2) which give valuable information on internal rotor dynamics and thus obtained data were interpreted on the basis of various proposed models for internal rotation. compound undergoes three-fold jumps at 25$^{\circ}$. The fact that the ratio $\tau$int(1) / $\tau$int(2) is close to 1.0 may be interpreted as indicating that methyl group in this C.

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25노트급 활주형 어선의 기본선형 개발에 관한 연구 (A Study on the Hull Form Development of the 25 Knots Class Planing Hull Form Fishing Boat)

  • 이귀주;좌순원;박명규;신영균
    • 한국해양공학회지
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    • 제17권5호
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    • pp.88-94
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    • 2003
  • A series of tests of 5 model ships, selected from a data survey of 10 Gross Tonnage actual fishing boats, were performed in two circulating water channels (Chosun University in Korea and WJFEL in Japan), in order to develop the basic hull form of a 25 knots-class fishing boat. Resistance tests, trim and sinkage measurements and wave pattern observations etc., were included in each I1wdel test, and the model test results were compared and analyzed. The result was as follows: P-4 hull form ship changed into Deep V type bow is the best hull form with good performance, especially with regard to ship's resistance efficiency.

In Vitro Sugar Accumulation in Juice Sacs of 'Shiranuhi' Mandarin

  • Moon, Doo-Gyung;Han, Sung-Gap;Joa, Jae-Ho;Kim, Chun-Hwan;Seong, Ki-Cheol
    • 원예과학기술지
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    • 제31권3호
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    • pp.269-274
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    • 2013
  • To further our understanding of sugar accumulation in 'Shiranuhi' mandarin [(C. unshiu ${\times}$ C. sinensis) ${\times}$ C. reticulate], we investigated the patterns of sugar uptake in juice sacs exposed to different concentrations of sucrose, fructose and glucose in vitro. Data was also collected on the change in weight and shape of the in vitro juice sacs over time. Soluble solids content, sugar content and acidity content were highest at 20% sucrose, fructose and glucose solution content; while fructose content was highest at 5% sucrose concentration. Furthermore, the juice sac's fresh weight was highest at 5% sucrose and lowest at 20% fructose content. The shape of the juice sacs also differed in different sugar concentration and type. Overall, sucrose, fructose and glucose content in juice sacs increased with the sugar concentration. These results suggest that sugar translocation into juice sacs is actively induced by high sugar concentration in the medium. Thus, it can be concluded that sugar and acid accumulation in juice sacs increased with sugar concentration in vitro culture.