• 방사선산업학회지
• /
• 제12권4호
• /
• pp.325-332
• /
• 2018

Carotid angiography covering the aortic arch includes contrast-enhanced magnetic resonance angiography (CEA), which is applied to a large region and usually employs contrast media. However, the use of contrast media can be dangerous in infants, pregnant women, and patients with chronic renal failure (CRF). Follow-up patients informed of a lesion may also want to avoid constant exposure to contrast media. We aimed to apply time-of-flight (TOF) angiography to a large region and compare its usefulness with that of CEA. Ten patients (mean age, 58 years; range, 45~75 years) who visited our hospital for magnetic resonance angiography (MRA) participated in this study. A 3.0 Tesla Achieva magnetic resonance imaging (MRI) system (Philips, Netherland) and the SENSE NeuroVascular 16-channel coil were employed for both methods. Both methods were applied simultaneously to the same patient. Three TOF stacks were connected to cover the aortic arch through the circle of Willis, and CEA was applied in the same manner. For the quantitative assessment, the acquired images were used to set the regions of interest (ROIs) in the common carotid artery (CCA) bifurcation, internal carotid artery, external carotid artery, middle cerebral artery, and vertebral artery, and to obtain the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) for the soft tissues. Three radiologists and one radiological resident performed the qualitative assessment on a 5-point scale - 1 point, "very bad"; 2 points, "bad"; 3 points, "average"; 4 points, "good"; and 5 points, "very good" - with regard to 4 items: (1) sharpness, (2) distortion, (3) vein contamination, and (4) expression of peripheral vessels. For the quantitative assessment, we estimated the mean SNR and CNR in each of the 5 ROIs. In general, the mean SNR was higher in TOF angiography (166.1, 205.2, 154.39, 172.23, and 161.95) than in CEA(92.05, 95.43, 84.76, 73.69, and 88.3). Both methods had a similar mean CNR: 67.62, 106.71, 55.9, 73.74, and 63.46 for TOF angiography, and 67.82, 71.19, 60.52, 49.45, and 64.07 for CEA. In all ROIs, the mean SNR was statistically significant (p<0.05), whereas the mean CNR was insignificant (p>0.05). The mean values of TOF angiography and CEA for each item in the qualitative assessment were 4.2 and 4.28, respectively for item 1; 2.93 and 4.55, respectively, for item 2; 4.6 and 3.13, respectively, for item 3; and 2.88 and 4.65, respectively, for item 4. Therefore, TOF angiography had a higher mean for item 3, and CEA had a higher mean for items 2 and 4; there was no significant difference between the two methods for item 1. The results for item 1 were statistically insignificant (p>0.05), whereas the results for items 2~4 were statistically significant (p<0.05). Both methods have advantages and disadvantages and they complement each other. However, CEA is usually applied to a large region covering the aortic arch. Time-of-flight angiography may be useful for people such as infants, pregnant women, CRF patients, and followup patients for whom the use of contrast media can be dangerous or unnecessary, depending on the circumstance.

• Journal of Acupuncture Research
• /
• 제27권6호
• /
• pp.1-10
• /
• 2010

Objectives : The aim of this systematic review was to assess the efficacy of acupuncture and its relevant modality on post-stroke muscle spasticity Methods : We included 7 randomized controlled trials(RCTs) and 1 crossover study on acupuncture on the post-stroke muscle spasticity. Articles searches were performed in various databases in October 2009. Eight studies from 38 articles met the inclusion criteria and were used to assess the quality of clinical trials by means of Jadad scale, STRICTA, CONSORT statement and cochrane-handbook for systematic reviews of interventions. Results : Electrical stimulation such as electroacupuncture and TENS on acupoints was used in five studies. Repeatition of electroacupuncture showed significant decrease of the post-stroke muscle spasticity and persistence of the effect. Only three studies were assessed high quality as the methodological assessment tool(Jadad scale) and none of the studies matched STRICTA recommendations. Conclusions : This systematic review shows that there is beneficial effects of electroacupuncture on the post-stroke muscle spasticity. Further study of large population with high methodological quality will be needed.

• 임상간호연구
• /
• 제25권2호
• /
• pp.142-150
• /
• 2019

Purpose: The aim of this study was to evaluate the efficiency of the Humpty Dumpty Falls Scale as one of the falls risk assessment tools, and also to evaluate risk factors as predictors of falls in pediatric patient populations. Methods: In a retrospective, case-control design with data from the electronic medical records of 13 pediatric patients who fell and 1,941 who did not fall before matching and 429 who did not fall after matching by gender, age, diagnosis, and length of stay. Results: All the variables showed no significant differences after matching. At the cutoff score of 13, sensitivity, specificity, negative and positive predictive values were 92.3%, 37.1%, 99.9%, and 0.01%, respectively. The area under the Receiver Operating Characteristics was 0.597. The results from the logistic regression showed that the pediatric inpatient population who had higher risk scores was significantly associated with falls. The odds ratios ranged from 1.31 to 4.71 with 90% confidence interval. Conclusion: The saturation impairments criterion as one of the diagnostic parameter was negatively associated with falls, but the relative risk score was higher than the other criteria. Therefore, it seems that the diagnostic parameter seems to be required to verify results through large sample studies.

• Korean Chemical Engineering Research
• /
• 제55권5호
• /
• pp.609-617
• /
• 2017

목질계 바이오매스는 바이오 연료 및 바이오 화학제품 생산을 위한 재생 가능 자원이다. 푸르푸랄(furfural, FF)은 목질계 바이오매스의 헤미셀룰로스로부터 화학적 촉매전환으로 유도되는 주요한 플랫폼 케미칼이다. 테트라히드로푸르푸릴 알코올(Tetrahydrofurfuryl alcohol, THFA)은 FF의 유도체로 열적 화학적 안정성을 지닌 친환경 용매로 이용 가능하다. FF를 THFA로 전환하는 실험적 연구가 다수 존재함에도 불구하고, FF로부터 THFA의 대량생산에 관한 경제적 실현가능성에 관한 연구는 거의 수행되지 않았다. 개발된 전환기술의 상용화 단계에서 기술적 병목점 확인과 스케일업 문제의 해결을 위한 정보를 얻기 위해 실증플랜트 규모의 연구가 필요하다. 본 연구에서는 FF의 THFA로의 화학적 촉매전환에 대해 공정 시뮬레이션 및 기술경제성 평가가 수행되며, 3가지 단계(통합 공정 디자인, 열 통합, 경제성 평가)를 거친다. 실험연구 결과를 기반으로 전환공정과 분리공정을 포함하는 실증플랜트 규모의 통합공정이 설계된다. FF 처리량은 일일 255톤이며, FF로부터 THFA로의 수율은 63.2~67.9 mol%이다. 통합공정에 대해 열 통합을 수행하여 가열요구량을 최초 대비 14.4~16.4% 감소시킬 수 있었다. 최종적으로 경제성 평가를 통해 전체 공정의 주요 비용원을 분석하고 THFA의 최소판매가격을 결정하였다. 개발된 공정에서 생산되는 THFA의 최소판매가격은 1톤당 2,120~2,340 달러로, 현재 THFA의 시장 가격에 근접한다.

• Environmental Engineering Research
• /
• 제15권2호
• /
• pp.123-126
• /
• 2010

Modeling non-point pollution across multiple scales has become an important environmental issue. As a more representative and practical approach in quantifying and qualifying surface water, a modular neural network (MNN) was implemented in this study. Two different site-scales ($1.5\;{\times}\;10^5$ and $1.62\;{\times}\;10^6\;m^2$) with the same plants, soils, and paddy field management practices, were selected. Hydrologic data (rainfall, irrigation and surface discharge) and water quality data (time-series nutrient loadings) were continuously monitored and then used for the verification of MNN performance. Correlation coefficients (R) for the results predicted from the networks versus measured values were within the range of 0.41 to 0.95. The small block could be extrapolated to the large field for the rainfall-surface drainage process. Nutrient prediction produced less favorable results due to the complex phenomena of nutrients in the drainage water. However, the feasibility of using MNN to generate improved prediction accuracy was demonstrated if more hydrologic and environmental data are provided. The study findings confirmed the estimation accuracy of the upscaling from a small-segment block to large-scale paddy field, thereby contributing to the establishment of water quality management for sustainable agriculture.

• 한국물환경학회지
• /
• 제38권4호
• /
• pp.177-189
• /
• 2022

Nature-based Solutions (NbS) are defined as practical and technical approaches to restoring functioning ecosystems and biodiversity as a means to address socio-environmental challenges and provide human-nature co-benefits. This study reviews NbS-related literature to identify its key characteristics, techniques, and challenges for its application in climate-adaptive water management. The review finds that NbS has been commonly used as an umbrella term incorporating a wide range of existing ecosystem-based approaches such as low-impact development (LID), best management practices (BMP), forest landscape restoration (FLR), and blue-green infrastructure (BGI), rather than being a uniquely-situated practice. Its technical form and operation can vary significantly depending on the spatial scale (small versus large), objective (mitigation, adaptation, naturalization), and problem (water supply, quality, flooding). Commonly cited techniques include green spaces, permeable surfaces, wetlands, infiltration ponds, and riparian buffers in urban sites, while afforestation, floodplain restoration, and reed beds appear common in non- and less-urban settings. There is a greater lack of operational clarity for large-scale NbS than for small-scale NbS in urban areas. NbS can be a powerful tool that enables an integrated and coordinated action embracing not only water management, but also microclimate moderation, ecosystem conservation, and emissions reduction. This study points out the importance of developing decision-making guidelines that can inform practitioners of the selection, operation, and evaluation of NbS for specific sites. The absence of this framework is one of the obstacles to mainstreaming NbS for water management. More case studies are needed for empirical assessment of NbS.

• 한국정밀공학회지
• /
• 제31권5호
• /
• pp.403-409
• /
• 2014

For ground-based telescope application, the performance assessment of tip-tilt actuator is important because the optical quality of telescope depends upon the windshake compensation ability of the fast steering secondary mirror. But it is difficult to measure the performance characteristics of the actuators due to the large size mirror and test facilities including the vacuum support and structural frame. In this paper, the full-scale tip-tilt test bed for the large size secondary mirror with diameter of 1m is built and the several tests are performed including the range, resolution and frequency response function. From the measurement results, it is shown that the tip-tilt actuator can successfully compensate the windshake with frequency of maximum 12 Hz and be a candidate for the Giant Magellan Telescope.

• Journal of Welding and Joining
• /
• 제28권3호
• /
• pp.65-72
• /
• 2010

Some structural members of large-scale marine vessels such as large-scale offshore structures and very large container ships are assembled by very thick plates of which thickness exceeds 60mm. Also, high-tensile steels have been selected to meet the required structural strength and fatigue strength. Generally, multi-pass welding method such as FCA(Flux-Core Arc) welding has been used to join the thick plates. Considering the welding residual stresses, fatigue strength of the welded joints of thick plates should be assured since the residual stress influences the fatigue strength. This paper presents a numerical procedure to investigate the residual stress of structure joined by multi-pass FCA welding so that it can be incorporated into the fatigue strength assessment considering the effect of welding residual stress. The residual stress distribution is also measured by X-Ray diffraction method. The residual stress obtained by the computational model also has been compared with that of experiment. The results of FEA are in very good agreement with the experimental measurements.

• 한국측량학회지
• /
• 제19권2호
• /
• pp.173-181
• /
• 2001

수치지도 일반화 과정을 통해 생성된 수치지도의 공간데이터에 관한 품질을 평가하는 것은 매우 중요하다. 본 연구에서는, 공간데이터 품질유지 측면에서, 변환된 수치지도 데이터가 해당 축척의 수치지도 규정 및 정확도에 위배되지 않도록 하기 위해 이론적 기대정확도의 허용범위를 살펴보고 공간데이터의 품질 평가 기준을 정립하였다. 그리고, 대축척 수치지도를 소축척 수치지도로 변환할 때, 단순화, 완만화, 정리 등과 같은 처리과정을 통해 복잡성을 감소시키게 되면 공간적인 위치변화는 항상 발생하게 될 것이다. 따라서, 각 지점의 변환된 위치에 관한 공간정확도를 분석하는 것은 매우 힘든 일이기 때문에 평가방법으로서 버퍼링기법을 이용하였다. 비록 축척 1/1,000 및 l/5,000에 대한 일반적인 위치오차의 허용범위는 관련법규를 기준으로 결정되었다 하더라도, 각 처리요소에 적용된 알고리즘들은 서로 다른 특성을 가지고 있기 때문에, 알고리즘에 따라 적절한 매개변수와 허용오차를 결정하지 않는다면, 일반화 처리후의 허용범위를 만족할 수 없을 것이다. 허용범위에 근거를 둔 각 알고리즘의 변수에 관한 본 연구에서의 실험결과는 단순화 및 위치오차의 매개변수가 각각 0.2617 m, 0.4617 m를 나타내고 있었다.

• 한국산업보건학회지
• /
• 제8권2호
• /
• pp.264-271
• /
• 1998

A pilot study was undertaken to examine the possible health effects of electromagnetic fields(EMFs). The purpose of this study was to investigate of the EMFs exposures of personal environment, 60Hz magnetic fields. An experimental study was performed for six weeks of January-February 1998 to compare changes in melatonin levels in urine of 20 subjects during their normal sleeping hours and each 20 subjects in occupational and non-occupational group measured personal 24-h continual exposure, using EMDEX II (for 40-800Hz, Enertech Consultant, Inc.). An urine samples were collected 3 times a day(before sleep or around 24:00 ; immediately after wake-up ; around noon) for an week from each subjects and analyzed by radioimmunoassay. This study did not significant difference for the subjective average melatonin levels between occupational and nonoccupational groups exposed to electromagnetic fields. The mean personal exposure levels of occupational group were $0.215{\mu}T$, whereas non-occupational group were $0.18{\mu}T$. Occupational group were exposed more highly while at work. Finally, this study would provide significant data for furture study of exposure assessment of magnetic fields. A large scale study concerning more detailed exposure assessment should provide important information on health risk assessment of MFs. Further study should provide information on the contribution of various sources and the relationship between melatonin and immune system activity.