• Title/Summary/Keyword: cross sectional study

Search Result 5,037, Processing Time 0.029 seconds

Heat Transfer Performance of the Duct with Various Cross Section in Heat Exchanger (단면형상 변화에 따른 전열교환기 열전달 특성변화에 대한 연구)

  • Kim, Eung-Bok;Han, Min-Sub;Kim, Nae-Hyun;Won, Tae-Yeon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.22 no.5
    • /
    • pp.322-327
    • /
    • 2010
  • It is a critical task to keep the ventilation system working in a proper and efficient manner in large multi-storey buildings, and the enthalpy exchanger is becoming an increasingly important part of the ventilation system by playing the function of channeling heat and moisture. We present a computational study on the heat transfer performance of the cross-flow enthalpy exchanger, which is in large use for residential buildings. The ducts are considered whose cross-sectional shapes resemble triangle and longitudinal centerline a cosine wave. It is shown that, as the cross-sectional shape departs from triangle, the heat transfer performance of the duct tends to deteriorate. Also, applying the wave-like shape to the longitudinal centerline of the duct increases the rate of heat transfer and the applied pressure-gradient at the same time. The origin of the performance variations in the cases considered are quantitatively analyzed and discussed.

Experimental Study on the Effect of the Area Ratio between Shaft and Tunnel and Heat Release Rate on the Plug-holing Phenomena in Shallow Underground Tunnels (저심도 도로터널에서 터널과 수직환기구의 단면적 비와 열방출률이 Plug-holing 현상에 미치는 영향에 관한 실험연구)

  • Hong, Kibea;Na, Junyoung;Ryou, Hong Sun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.20 no.4
    • /
    • pp.619-625
    • /
    • 2019
  • It is difficult to design because of the plug-holing phenomenon in which the amount of smoke discharged from the vertical vent is smaller than the designed amount of smoke. In this study, the effect of cross-sectional area ratio of tunnel and natural ventilation and heat release rate of fire source on plug-holing phenomenon occurring in natural ventilation system was experimentally analyzed. In the experiment model reduced to 1/20 size, the aspect ratio of the tunnel and the vertical vent was fixed, and the influence on the plug-holing phenomenon was confirmed by varying the sectional area ratio of the tunnel and the vertical vent. Experimental results show that the plug-holing phenomenon is caused by the comparison of the smoke boundary layer temperature with the temperature in the vertical vents, and the flow and temperature distribution characteristics under the vertical vents are changed as the cross-sectional area ratio of the tunnel and vertical vents increases. The plug-holing phenomenon is affected by the cross-sectional area ratio between the tunnel and the vertical ventilation. The greater the cross-sectional area ratio, the greater the probability of plug-holing.

The Effect of the Axial Plane on Measurement of Available Bone Height for Dental Implant in Computed Tomography of the Mandible (하악의 전산화 단층사진에서 횡단면이 임플랜트를 위한 가용골 높이의 결정에 미치는 영향)

  • Jhin, Min-Ju
    • Journal of Periodontal and Implant Science
    • /
    • v.32 no.2
    • /
    • pp.379-388
    • /
    • 2002
  • For the success of dental implant, accurate radiographic evaluation is prerequisite for planning the location of the osseointegrated implants and avoiding injury to vital structures. CT/MPR(computed tomography/multiplanar reformation) shows improved visualization of inferior alveolar canal. In order to obtain cross-sectional images parallel to the teeth, the occlusal plane is used to orientate for the axial plane. If the direction of axial plane is not parallel to the occlusal plane, the reformatted cross-sectional scans will be oblique to the planned fixture direction and will not show the actual dimension of the planned fixture's location. If the available bone height which measured in the cross-sectional view is much greater than the actual available bone height, penetration of canal may occur. The aim of this study is to assess the effect of the axial plane to measurement of available bone height for dental implant in computed tomography of the mandible. 40 patients who had made radiographic stents and had taken CT were selected. The sites that were included in the study were 45 molar regions. In the central panoramic scan, the length from alveolar crest to superior border of inferior alveolar canal(available bone height, ABH) was measured in direction of reformatted cross-sectional plane(uncorrected ABH). Then, length from alveolar crest to superior border of canal was measured in direction of stent(corrected ABH). The angle between uncorrected ABH and corrected ABH was measured. From each ABH, available fixture length was decided by $Br{{\aa}}nemark$ system. The results were following ; the difference between two ABHs was statistically significant in both first and second molar(p< 0.01). The percentage of difference more than 1 mm was 8.7% in first molar and 15.5% in second molar. The percentage of difference more than 2 mm was 2.0% in first molar and 6.6% in second molar. The maximum value of difference was 2.5 mm in first molar and 2.2 mm in second molar. The correlations between difference of 2 ABHs and angle was positive correlations in both first and second molar. The correlation coefficient was 0.534 in first molar and 0.728 in second molar. The second molar has a stronger positive correlation. The percentage of disagreement between 2 fixture lengths from two ABHs was 24.4% in first molar and 28.9% in second molar.

Systematic Review of Research into the Psychological Aspects of Prostate Cancer in Asia: What do we Know?

  • Chambers, Suzanne Kathleen;Hyde, Melissa Karen;Ip, David Fu-Keung;Dunn, Jeffrey Charles;Gardiner, Robert Alexander
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.14 no.4
    • /
    • pp.2621-2626
    • /
    • 2013
  • Background: To review the peer reviewed literature on the psychological aspects of the prostate cancer experience of men in Asia. Materials and Methods: Medline and PsycINFO, CINAHL, ProQuest, and Web of Science (1999 - November Week 4, 2012) were searched. Inclusion criteria were: included men with prostate cancer and/or their partners or caregivers who identify as Asian recruited in an Asian country; and assessed health-related quality of life, psychological and social adjustment relating to prostate cancer and published in English after $1^{st}$ January 1999 and prior to $30^{th}$ November, 2012. Study aims; design; quality; level of evidence, and key results were assessed. Results: 43 articles met all inclusion criteria and were retained for initial review. Of these most focussed on health-related QOL with only five evidence Level IV studies from Japan and Taiwan including a specific psychological focus. Of these, one was a cross-sectional case control study; three were cross-sectional descriptive quantitative designs; one was a cross-sectional descriptive qualitative study. From the data available, a substantive sub group of men with prostate cancer (approximately one third) in these countries experience clinically high psychological distress and decision regret. Conclusions: Research on the psychological needs of men with the increasingly prevalent condition of prostate cancer in Asian countries is scant with only a small number of low level evidence descriptive studies identified. Future research to underpin the development and evaluation of effective and culturally relevant psychological and supportive care interventions for such men is urgently needed.

Comparison of the Cross-Sectional Area of Longus Colli and Muscle Activity of Sternocleidomastoid in Subjects With Forward Head Posture on the Two Craniocervical Flexion Methods

  • Son, Min-chan;Hwang, Ui-jae;Jung, Sung-hoon;Ahn, Sun-hee;Kim, Hyun-a;Kwon, Oh-yun
    • Physical Therapy Korea
    • /
    • v.25 no.2
    • /
    • pp.62-70
    • /
    • 2018
  • Background: The craniocervical flexion (CCF) exercise is one of the effective exercise in correcting forward head posture (FHP). However, some people with FHP achieve CCF with compensatory movements, for example, low cervical flexion using superficial neck flexors such as the sternocleidomastoid (SCM) muscle. No study has yet investigated whether a dual­pres ure biofeedback unit (D-PBU) method to prevent low cervical flexion would be helpful in performing pure CCF movement. Objects: The purpose of this study was to compare the effects of the CCF using D-PBU method and the traditional CCF method on the cross-sectional area (CSA) of the longus colli muscle (LCM) and the activity of SCM muscle in subjects with FHP. Methods: Twenty­four FHP subjects (male: 16, female: 8) were recruited for this study. All subjects performed CCF using two different methods: the traditional CCF method and the CCF using D-PBU method. The CSA of the LCM was measured via ultrasound, and surface electromyography was used to measure SCM muscle activity. Results: The change in CSA of the LCM was significantly larger during the CCF using D-PBU method ($1.28{\pm}.09$) compared with the traditional CCF method ($1.19{\pm}.08$) (p<.05). The SCM muscle activity using the CCF using D-PBU method ($2.01{\pm}1.97$ %MVIC) was significantly lower than when using the traditional CCF method ($2.79{\pm}2.32$ %MVIC) (p<.05). Conclusion: The CCF using D-PBU method can be recommended for increasing LCM activation and decreasing SCM muscle activity during CCF movement in subjects with FHP.

Analysis of Reports on Observational Studies Published in the Korean Journal of Women Health Nursing based on the STROBE Guideline (여성건강간호학회지에 게재된 조사연구 보고 분석: STROBE 지침에 근거하여)

  • Kim, Sue;Oh, Hyun-Ei;Song, Ju-Eun;Kim, Myounghee;Ahn, Sukhee;Lee, Eun-Joo;Jun, Eun-Mi;Cheon, Sukhee
    • Women's Health Nursing
    • /
    • v.20 no.4
    • /
    • pp.287-296
    • /
    • 2014
  • Purpose: The purpose of this study was to analyze the quality of reports on observational studies published in the Korean Journal of Women Health Nursing (KJWHN). Methods: Forty-six studies using cross-sectional designs published in KJWHN from January 2011 to June 2013 were selected for analysis. Selected articles were reviewed and evaluated by three reviewers using the 22 items of the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement. As some of 22 items had more than one check point, further broken down, 34 checklist items were used for analysis. Results: Overall, the reviewed studies provided sufficient descriptions for many STROBE items. Seven of the 34 items were found to be not applicable, and 15 of the remaining 27 items (55.5%) were evaluated as 'sufficient' in reporting. Only one study included a flow diagram illustrating participation and this lack of flow diagram was the weakest area of reporting in this review. Conclusion: Clearer reporting of cross-sectional studies can be attained by attention to vulnerable areas of reporting, such as including a flow diagram of participants, descriptions of sources of bias and reason for non-participation, and describing limitations of the study. Issues regarding the application of STROBE statement items should be actively discussed in order to aid future revision and clarification of items included in STROBE statement.