• Geomechanics and Engineering
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• 제18권1호
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• pp.71-83
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• 2019

This investigation presented conventional triaxial and creep-permeability tests on sandstones considering thermally-induced damage (TID). The TID had no visible effects on rock surface color, effective porosity and permeability below $300^{\circ}C$ TID level. The permeability enlarged approximately two orders of magnitude as TID increased to $1000^{\circ}C$ level. TID of $700^{\circ}C$ level was a threshold where the influence of TID on the normalized mass and volume of the specimen can be divided into two linear phases. Moreover, no prominent variations in the deformation moduli and peak strength and strain appeared as TID< $500^{\circ}C$ level. It is interesting that the peak strength increased by 24.3% at $700^{\circ}C$ level but decreased by 11.5% at $1000^{\circ}C$ level. The time-related deformation and steady-state creep rate had positive correlations with creep loading and the TID level, whereas the instantaneous modulus showed the opposite. The strain rates under creep failure stresses raised 1-4 orders of magnitude than those at low-stress levels. The permeability was not only dependent on the TID level but also dependent on creep deformation. The TID resulted in large deformation and complexity of failure pattern for the sandstone.

• Journal of Korean Neurosurgical Society
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• 제37권1호
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• pp.44-47
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• 2005

Objective: The purpose of this study is to investigate the elevated blood glucose levels in the postoperative period are associated with an increased risk of deep wound infection in diabetic individuals undergoing lumbar spine surgery. Methods: Of 2896 patients who underwent lumbar spine operations by one surgeon between 1993 and 2002, 329(11.4%) were diabetics. The rate of deep wound infections in diabetic patients was 6.4%, versus 3.2% for nondiabetics. 152 patients had their operation before implementation of the protocol and 177 after implementation. Charts of the diabetic patients were reviewed. Mean blood glucose levels were calculated from documented results of finger-stick glucometer testing. Results: Twenty-one diabetic patients suffered deep wound infection. Infected diabetic patients had a higher mean blood glucose level through the first 2 postoperative days than noninfected patients($230{\pm}6.9$ versus $175{\pm}3.8mg/dL$; p<0.003) and had a long operation time($216{\pm}57.9$ versus $167.5{\pm}42.2$ minute; p<0.05). Multivariable logistic regression showed that mean blood glucose level for the first 2 postoperative days, long operation time, and use of the instrumentation(p<0.02) were all related predictiors of deep wound infection. Institution of a protocol of postoperative continuous intravenous insulin to maintain blood glucose level less than 200mg/dL was began in september 1997. This protocol resulted in a decrease in blood glucose levels for the first 2 postoperative days and a concomitant decrease in the proportion of patients with deep wound infection, from 8.3%(11/132) to 5.1%(10/195) (p<0.02). Conclusion: The incidence of deep wound infection in diabetic patients is reduced after implementation of a protocol to maintain mean blood glucose level less than 200mg/dL in the immediate postoperative period.

• 전기전자학회논문지
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• 제27권4호
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• pp.556-560
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• 2023

본 연구에서는 4H-SiC Epi Surface에 Nitrogen implantation 공정이 깊은준위결함과 lifetime에 미치는 영향을 비교분석하였다. Deep Level Transient Spectroscopy (DLTS)와 Time Resolved Photoluminescence (TR-PL)을 사용하여 깊은준위결함과 carrier lifetime을 측정하였다. As-grown SBD에서는 0.16 eV, 0.67 eV, 1.54 eV 에너지 준위와 implantation SBD의 경우 0.15 eV 준위에서의 결함을 측정되었으며, 이는 nitrogen implantation으로 불순물이 titanium 및 carbon vacancy를 대체됨으로 lifetime killer로 알려진 Z_1/2, EH_6/7 준위 결함은 감소하였다.

• 한국수자원학회논문집
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• 제54권spc1호
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• pp.1061-1069
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• 2021

최근 이상 기후로 인해 극한 호우 및 국지성 호우의 규모 및 빈도가 증가하여 하천 주변의 홍수 피해가 증가하고 있다. 이에 따라 하천 또는 유역 내 수문학적 시스템의 비선형성이 증가하고 있으며, 기존의 물리적 기반의 수문 모형을 활용하여 홍수위를 예측하기에는 선행시간이 부족한 한계점이 존재한다. 본 연구에서는 Deep Neural Network (DNN) 및 Long Short-Term Memory (LSTM)기반의 딥러닝 기법을 적용하여 울산시(태화교) 지점의 수위를 0, 1, 2, 3, 6, 12시간에 대해 선행 예측을 수행하였고 예측 정확도를 비교 분석하였다. 그 결과 sliding window 개념을 적용한 DNN 모형이 선행시간 12시간까지 상관계수 0.97, RMSE 0.82 m로 가장 높은 정확도를 보이고 있음을 확인하였다. 향후 DNN 모형을 활용하여 딥러닝 기반의 수위 예측을 수행한다면 기존의 물리적 모형을 통한 홍수위 예측보다 향상된 예측 정확도와 충분한 선행시간을 확보할 수 있을 것으로 판단된다.

• 한국식품위생안전성학회지
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• 제10권3호
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• pp.155-161
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• 1995

In the study, attempts were made to investigate the safety of the deep-fried instant noodles. A total of 50 deep-fried instant noodles were puchased from a local supermarket. Acid value , peroxide value, preservatives, heavy metals and pesticide residues were determined. Acid value(AV) and peroxide value(POV) of deep-fried instant noodles were lower than the Food Law in force. Any preservatives were not detected in all deep-fried instant noodles. The level of all heavy metals and pesticide residues found in deep-fried instant noodles were fairly low, and pesticide residues in deep-fried instant noodles was almost removed after cooking. It was conclued from these results that deep-fried instant noodles may be no harmful in oxidative stability(AV, POV) and sanitary safety(preservatives, heavy metals and pesticides).

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.147-147
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• 2018

In this article, we use an open source software library: TensorFlow, developed for the purposes of conducting very complex machine learning and deep neural network applications. However, the system is general enough to be applicable in a wide variety of other domains as well. The proposed model based on a deep neural network model, LSTM (Long Short-Term Memory) to predict the river water level at Okcheon Station of the Guem River without utilization of rainfall - forecast information. For LSTM modeling, the input data is hourly water level data for 15 years from 2002 to 2016 at 4 stations includes 3 upstream stations (Sutong, Hotan, and Songcheon) and the forecasting-target station (Okcheon). The data are subdivided into three purposes: a training data set, a testing data set and a validation data set. The model was formulated to predict Okcheon Station water level for many cases from 3 hours to 12 hours of lead time. Although the model does not require many input data such as climate, geography, land-use for rainfall-runoff simulation, the prediction is very stable and reliable up to 9 hours of lead time with the Nash - Sutcliffe efficiency (NSE) is higher than 0.90 and the root mean square error (RMSE) is lower than 12cm. The result indicated that the method is able to produce the river water level time series and be applicable to the practical flood forecasting instead of hydrologic modeling approaches.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.723-730
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• 2019

Acquiring instrumentation signals generated from nuclear power plants (NPPs) is essential to maintain nuclear reactor integrity or to mitigate an abnormal state under normal operating conditions or severe accident circumstances. However, various safety-critical instrumentation signals from NPPs cannot be accurately measured on account of instrument degradation or failure under severe accident circumstances. Reactor vessel (RV) water level, which is an accident monitoring variable directly related to reactor cooling and prevention of core exposure, was predicted by applying a few signals to deep neural networks (DNNs) during severe accidents in NPPs. Signal data were obtained by simulating the postulated loss-of-coolant accidents at hot- and cold-legs, and steam generator tube rupture using modular accident analysis program code as actual NPP accidents rarely happen. To optimize the DNN model for RV water level prediction, a genetic algorithm was used to select the numbers of hidden layers and nodes. The proposed DNN model had a small root mean square error for RV water level prediction, and performed better than the cascaded fuzzy neural network model of the previous study. Consequently, the DNN model is considered to perform well enough to provide supporting information on the RV water level to operators.

• 대한물리의학회지
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• 제6권4호
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• pp.497-504
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• 2011

Purpose : Chronic cervical pain is a common source of disability in society. There has been no research regarding the amount of pressure for the deep cervical flexors during cranio-cervical flexion exercise (CCFE). The purpose of this study is to determine optimal pressure levels to facilitate deep cervical muscles (longus colli & longus capitis) during cranio-cervical flexion exercise, using ultrasound measurement of the muscles. Methods : Using a cross-sectional design, the study was performed in an experimental group of 19 subjects (7 men, 12 women) with no cervical pain. Participants were instructed to perform the CCFE, and during the five incremental stages of the test, changes in thickness, as compared to resting baseline values, were measured using ultrasonography for sternocleidomastoid muscle (SCM) and deep cervical muscles (DCF). Results : Both DCF and SCM muscles demonstrated an increase in recruitment with each progressive phase of the test. In comparing the different pressure increments, the most significant changes found in DCF thickness were between phase 2 and phase 3 (p<.05). However no differences were found between pressure increments for SCM thickness (p>.05). Conclusion : The results suggest 26 mm Hg as the optimal pressure level during cranio-cervical flexion exercise for facilitation of deep cervical flexor.

• 생명과학회지
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• 제19권7호
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• pp.923-927
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• 2009

STZ(Streptozotocin)를 이용하여 제 1형 당뇨를 유발시킨 생쥐에게 해양심층수를 음용시켜, 혈당치의 변화 및 파괴된 췌도에 미치는 영향에 대하여 연구하였다. 그 결과 수돗물을 음용시킨 생쥐에 비해서 해양심층수를 음용시킨 생쥐의 혈당이 낮아지고, 파괴되었던 췌도의 면적이 넓어졌으며, 췌도 내에 정상적인 $\beta$-세포의 수도 많아진 점으로부터, 해양심층수의 음용이 당뇨병의 증상완화에 효과가 있음이 밝혀졌다. 이러한 효과는 해양심층수에 포함된 $Mg^{2+}$의 효과인 것으로 생각되었다.

• 수산해양기술연구
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• 제23권4호
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• pp.163-168
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• 1987

1984, 85, 87년에 걸쳐 7~8월에 부산402호(380GT, 850PS)를 이용하여 한국동해안 주요항구 입구와 외해에서 해중소음과 선박기관소음의 해중음압 분포와 그 음의 스펙트럼 특성을 해황별로 환경소음과 선박기관진동소음으로서 비교.검토한 결과를 요약하면 다음과 같다. 1. 풍속 0~2m/sec일 때 깊이 5m층에서의 환경소음의 음압준위는 부산 동항에서는 108dB, 부산 남항에서는 106dB, 구룡포항에서는 101dB로서 항내에 소음원이 많을 때는 높고, 그렇지 않을 때는 낮았다. 한반도와 울릉도 중간의 외해에서는 다같이 100dB로서 항구 부근보다 낮았다. 또 외해에 있어서 깊이에 따른 음압의 분포는 깊이 20m, 70m 층에서는 5m층에서 보다 1~2dB 낮고, 100m층 이하에서는 100dB로 거의 일정했다. 2. 풍속 10~15m/sec일 때, 외해에서의 환경소음의 음압준위는 5m층에서 108dB이고 그 후 점차 낮아져 70m 층에서 100dB이며, 그 이하에서는 100dB로 모두 같았다. 선박기관진동소음의 음압준위는 깊이 5, 50, 100, 150, 200m층에서 각각 146, 125, 112, 110, 104dB로서 깊어짐에 따라 점차 낮아졌다. 3. 풍속 10~15m/sec일 때 외해의 깊이 5m층에서 10Hz, 100Hz, 1KHz, 10KHz의 주파수대에 있어서의 스펙트럼 레벨은 해중소음이 각각 86, 75, 61, 32dB, 선박진동소음이 각각 105, 95, 86, 55dB로서 후자가 전자보다 20dB 정도 높았다. 200m층에 있어서는 전자가 80, 68, 47, 26dB, 후자가 82, 70, 59, 31dB로서 후자가 전자보다 4dB 정도 높았다.