• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.431-446
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• 2023

Samama wood (Anthocephalus macrophyllus (Roxb) Havil) is a fast-growing and lesser-utilized wood species that has inferior properties; therefore, its quality needs to be improved. This research aimed to determine the effect of citric acid impregnation at high curing temperatures on the dimensional stability and mechanical properties of wood. Citric acid solution with 10% concentration (w/w) was impregnated into wood samples by vacuum-pressure method (-0.5 cmHg, 30 min; 0.7 MPa, 3 h), followed by curing process at 140℃, 160℃, and 180℃ of temperature for 1 h. In comparison, the other wood samples were heat treated at the same temperatures and time. The results showed that the increase in curing and heat temperatures for both treatments were directly proportional to the dimensional stability, but inversely proportional to the mechanical properties. Citric acid impregnated had higher density, dimensional stability, and mechanical properties, except for modulus of rupture, than that of heat treatment. The optimum temperature is suggested at 160℃ in both treatments.

• Korean Journal of Radiology
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• 제22권5호
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• pp.751-758
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• 2021

Objective: Preoperative differentiation between inverted papilloma (IP) and its malignant transformation to squamous cell carcinoma (IP-SCC) is critical for patient management. We aimed to determine the diagnostic accuracy of conventional imaging features and histogram parameters obtained from whole tumor apparent diffusion coefficient (ADC) values to predict IP-SCC in patients with IP, using decision tree analysis. Materials and Methods: In this retrospective study, we analyzed data generated from the records of 180 consecutive patients with histopathologically diagnosed IP or IP-SCC who underwent head and neck magnetic resonance imaging, including diffusion-weighted imaging and 62 patients were included in the study. To obtain whole tumor ADC values, the region of interest was placed to cover the entire volume of the tumor. Classification and regression tree analyses were performed to determine the most significant predictors of IP-SCC among multiple covariates. The final tree was selected by cross-validation pruning based on minimal error. Results: Of 62 patients with IP, 21 (34%) had IP-SCC. The decision tree analysis revealed that the loss of convoluted cerebriform pattern and the 20th percentile cutoff of ADC were the most significant predictors of IP-SCC. With these decision trees, the sensitivity, specificity, accuracy, and C-statistics were 86% (18 out of 21; 95% confidence interval [CI], 65-95%), 100% (41 out of 41; 95% CI, 91-100%), 95% (59 out of 61; 95% CI, 87-98%), and 0.966 (95% CI, 0.912-1.000), respectively. Conclusion: Decision tree analysis using conventional imaging features and histogram analysis of whole volume ADC could predict IP-SCC in patients with IP with high diagnostic accuracy.

• 한국과학교육학회지
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• 제26권4호
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• pp.559-567
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• 2006

본 연구의 목적은 우리나라 초 중학생이 가진 과학 재능 및 흥미에 대한 학생, 학부모, 교사의 인식을 조사하여 비교해보고, 그 중에서 과학고 진학 희망 학생틀의 과학 재능 및 흥미에 대한 학생 본인, 학부모, 교사의 인식을 비교해보는 것이다. 본 연구의 대상은 한국의 한 개 광역시의 초 중학생 592명과 그들의 학부모 592명 및 그들의 지도교사들이었으며, 연구 방법은 질문지에 의한 조사 방법을 사용하였다. 본 연구의 결과는 다음과 같다. 첫째, 전체적으로 학생의 과학 재능 및 흥미에 대한 인식이 학생에 비해 교사나 학부모가 더 높은 것으로 나타났으며, 그 인식 정도는 세 집단 모두에서 학년이 높아질수록 낮아졌다. 둘째, 학생, 학부모의 경우는 남학생의 과학 재능과 흥미에 대한 인식이 여학생보다 높았던 반면, 교사의 경우는 성별에 따른 차이가 거의 없는 것으로 인식하였다. 셋째, 과학고등학교 진학에 대한 학생, 학부모, 교사의 의견의 일치도는 세 집단이 모두 일치하는 경우는 5%로 아주 적었고, 학생은 원하지만 학부모와 교사가 원하지 않는 경우와 학생은 원하지 않는데 학부모는 원하는 경우를 합하면 50% 정도로 의견의 불일치 정도가 상당히 컸다. 이상의 결과는 학생의 과학 분야의 진로 선택에서 학생의 의견과 적성이 우선적으로 반영될 수 있도록 학생, 학부모, 교사 간의 대화를 통한 의견 조율이 필요하며, 학생들이 현재로서는 과학 분야의 진로에 대해 부정적인 인식을 가지고 있는 경우라도 중학생 시기가 진로 탐색 시기임을 고려하여 학부모와 교사가 그 학생의 과학적 적성에 따라, 필요한 경우에는 과학 분야에 대해 흥미와 관심을 가질 수 있도록 적절한 진로 지도가 필요함을 시사해 준다.

• Journal of Korean Neurosurgical Society
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• 제67권1호
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• pp.94-102
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• 2024

Objective : The spontaneous intracerebral hemorrhage (ICH) remains a significant cause of mortality and morbidity throughout the world. The purpose of this retrospective study is to develop multiple models for predicting ICH outcomes using machine learning (ML). Methods : Between January 2014 and October 2021, we included ICH patients identified by computed tomography or magnetic resonance imaging and treated with surgery. At the 6-month check-up, outcomes were assessed using the modified Rankin Scale. In this study, four ML models, including Support Vector Machine (SVM), Decision Tree C5.0, Artificial Neural Network, Logistic Regression were used to build ICH prediction models. In order to evaluate the reliability and the ML models, we calculated the area under the receiver operating characteristic curve (AUC), specificity, sensitivity, accuracy, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR). Results : We identified 71 patients who had favorable outcomes and 156 who had unfavorable outcomes. The results showed that the SVM model achieved the best comprehensive prediction efficiency. For the SVM model, the AUC, accuracy, specificity, sensitivity, PLR, NLR, and DOR were 0.91, 0.92, 0.92, 0.93, 11.63, 0.076, and 153.03, respectively. For the SVM model, we found the importance value of time to operating room (TOR) was higher significantly than other variables. Conclusion : The analysis of clinical reliability showed that the SVM model achieved the best comprehensive prediction efficiency and the importance value of TOR was higher significantly than other variables.

• Korean Journal of Radiology
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• 제21권9호
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• pp.1104-1113
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• 2020

Objective: To assess the regional ventilation in patients with asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) using xenon-ventilation dual-energy CT (DECT), and to compare it to that in patients with COPD. Materials and Methods: Twenty-one patients with ACOS and 46 patients with COPD underwent xenon-ventilation DECT. The ventilation abnormalities were visually determined to be 1) peripheral wedge/diffuse defect, 2) diffuse heterogeneous defect, 3) lobar/segmental/subsegmental defect, and 4) no defect on xenon-ventilation maps. Emphysema index (EI), airway wall thickness (Pi10), and mean ventilation values in the whole lung, peripheral lung, and central lung areas were quantified and compared between the two groups using the Student's t test. Results: Most patients with ACOS showed the peripheral wedge/diffuse defect (n = 14, 66.7%), whereas patients with COPD commonly showed the diffuse heterogeneous defect and lobar/segmental/subsegmental defect (n = 21, 45.7% and n = 20, 43.5%, respectively). The prevalence of ventilation defect patterns showed significant intergroup differences (p < 0.001). The quantified ventilation values in the peripheral lung areas were significantly lower in patients with ACOS than in patients with COPD (p = 0.045). The quantified Pi10 was significantly higher in patients with ACOS than in patients with COPD (p = 0.041); however, EI was not significantly different between the two groups. Conclusion: The ventilation abnormalities on the visual and quantitative assessments of xenon-ventilation DECT differed between patients with ACOS and patients with COPD. Xenon-ventilation DECT may demonstrate the different physiologic changes of pulmonary ventilation in patients with ACOS and COPD.

• Journal of Animal Science and Technology
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• 제66권2호
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• pp.353-365
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• 2024

Rumen cannulation is a surgical technique used to collect rumen contents from ruminants. However, rumen cannulation surgery may potentially impact the composition of the rumen microbiota. This study aimed to examine the longitudinal alterations in the rumen microbiota composition of Hanwoo steers after cannulation surgery. In this study, eight Hanwoo steers were used; four steers underwent rumen cannulation surgery (cannulation group), while the remaining four were left intact (control group). Rumen samples were collected from all eight steers using the stomach tubing method on the day before surgery (day 0) and on postoperative days 1, 4, 7, 10, 14, 17, 21, 24, and 28, resulting in 80 samples (10 timepoints × 8 animals). The microbiota of all 80 samples were analyzed using 16S rRNA gene amplicon sequencing with Quantitative Insights into Microbial Ecology version 2 (QIIME2). There were no significant differences (p > 0.05) in all major phyla and most major genera representing at least 0.5% of total sequences across all 80 samples between the control and cannulation groups on the preoperative and postoperative days. However, while the alpha diversity indices did not differ (p > 0.05) between the two groups on the preoperative day, they significantly differed (p < 0.05) between the two groups on the postoperative days. Further, the overall microbial distribution based on both unweighted and weighted principal coordinate analysis plots significantly differed (p < 0.05) between the two groups on both the preoperative and postoperative days. Orthogonal polynomial contrasts indicated that major genera and microbial diversity in the cannulation group decreased following surgery but returned to their initial states by postoperative day 28. In conclusion, this study demonstrates that rumen cannulation surgery affects some major taxa and microbial diversity, suggesting that the rumen cannulation method can alter the composition of rumen microbiota in Hanwoo steers.

• 한국간담췌외과학회지
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• 제28권2호
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• pp.134-143
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• 2024

Backgrounds/Aims: The hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) is classified as the advanced stage (BCLC stage C) with extremely poor prognosis, and in current guidelines is recommended for systemic therapy. This study aimed to evaluate the surgical outcomes and long-term prognosis after hepatic resection (HR) for patients who have HCC combined with PVTT. Methods: We retrospectively analyzed 332 patients who underwent HR for HCC with PVTT at ten tertiary referral hospitals in South Korea. Results: The median overall and recurrence-free survival after HR were 32.4 and 8.6 months, while the 1-, 3-, and 5-year overall survival rates were 75%, 48%, and 39%, respectively. In multivariate analysis, tumor number, tumor size, AFP, PIVKA-II, neutrophil-to-lymphocyte ratio, and albumin-bilirubin (ALBI) grade were significant prognostic factors. The risk scoring was developed using these seven factors-tumor, inflammation and hepatic function (TIF), to predict patient prognosis. The prognosis of the patients was well stratified according to the scores (log-rank test, p < 0.001). Conclusions: HR for patients who have HCC combined with PVTT provided favorable survival outcomes. The risk scoring was useful in predicting prognosis, and determining the appropriate treatment strategy for those patients who have HCC with PVTT.

• 농업과학연구
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• 제50권3호
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• 한국작물학회지
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• 제69권2호
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• pp.78-87
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• 2024

중간물떼기 기간연장에 따른 벼 생육반응 변화를 분석한 결과는 다음과 같다. 1. 관행 2주간 중간물떼기 대비 중간물떼기 기간이 3주로 연장되었을 경우 수량 및 수량구성요소는 유의한 차이가 없다. 2. 중간물떼기 기간이 4주로 연장되었을 경우 임실률과 영화수, 수량이 급격하게 감소하였다. 3. 중간물떼기가 4주 이상 지속될 경우 NDVI, PRI, CWSI 값이 유의하게 변화하였다. 4. 중간물떼기 기간 연장에 따른 식생지수별 생육지표와의 관계를 분석한 결과 NDVI 대비 CWSI가 약 4일 정도 더 빠르게 한발 스트레스를 감지하였으며 가역적 스트레스 또한 용이하게 확인할 수 있었다.

• 헤리티지:역사와 과학
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• 제41권2호
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• pp.43-59
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• 2008

삽(?)은 유교 예법에 따른 상장례(喪葬禮) 도구로 나무로 틀을 만들고 그 위에 백포(白布)나 두꺼운 종이를 붙여 그림을 그린 후, 자루를 달아 들 수 있도록 한 것이다. "례기(禮記)"에 따르면 삽은 주대(周代)부터 사용되었던 것으로 기록되어 있는데, 우리나라의 "조선왕조실록(朝鮮王朝實錄)"이나 "국조오례의(國朝五禮儀)", "사례편람(四禮便覽)"에 나타난 삽의 용례와 크게 차이가 나지 않는다. 본고에서는 현존하는 조선시대 사대부가의 회격 회곽묘에서 발견되는 삽의 발굴 사례 및 문헌 기록을 통해 그 용례와 제작방식, 시기에 따른 유물의 특징에 대해 고찰하고자 한다. 삽은 신분에 따라 사용하는 개수와 그리는 문양이 다른데, 사대부가에서는 주로 '아(亞)'형의 불삽 1쌍과 구름 문양을 그린 화삽 1쌍을 사용하였다. 삽의 크기는 너비가 2자[척(尺)], 높이 2자[척(尺] 4치[촌(寸)]로 만들었는데 초주지나, 저주지로 두 번 싸고, 세 번째는 연창지로 쌌다. 그리고 나서 백저포, 마포, 무명, 공단 등으로 덮었다. 그 양면에 보불을 그리고 구름 변아(邊兒)에 운기를 그리는데 대개 주사 또는 진사를 사용하였다. 사대부가 회격 회곽묘에서 출토되는 삽은 광중에 부장된 것으로, 삽자루와 분리된 형태이다. 즉, 출토되는 삽은 발인행렬시 삽을 매달았던 5자 길이의 삽자루는 태워 없애고, 관의 좌우에 세워 넣은 것이다. 출토 유물의 검토를 통해서도 제작과정을 유추할 수 있다. 출토된 유물은 각(角)의 개수에 따라 각이 3개 달린 것과 2개 달린 것으로 대별된다. 먼저 각이 3개 달린 것(유형 I) 중에는 나무 통판을 사용하거나 대나무를 납작하게 갈라, 바구니처럼 엮은 것도 있다. 각이 3개인 삽은 비교적 조선 전기에 집중되어 있으며, 전체적인 형태에 비해 그 제작방식이 다양한 편으로 생각된다. 반면 각이 2개 달린 삽의 경우에는 비교적 정형화된 제작방식이 보인다. 직사각형이나 역사다리꼴로 몸통부분을 만든 후, 2개의 각이 달린 삽의 윗부분을 연결한 형태이다. 다만 상단면을 곡선(유형 II) 또는 직선(유형 III)으로 처리하는 것이 다르다. 이러한 제작방식은 각이 3개 달린 것에 비해 간단하며, 제작기법 상의 차이는 크지 않다. 특히 상단면을 직선으로 처리하는 방식은 오늘날까지도 사용되고 있다. 분석에 사용된 30건 중 묘주의 몰년, 즉 삽의 제작 연대가 명확한 것만 선택하여 분석한 결과, 유형 I은 16세기 전반에 집중되어 있음을 알 수 있다. 이어 유형 II는 16세기 후반부터 17세기 후반, 유형 III은 17세기 전반부터 18세기 전반까지 고르게 분포하고 있다. 요컨대 삽의 형태는 유형 I에서 유형 II로, 다시 유형 II에서 유형 III으로 변화하고 있는 것으로 생각된다. 17세기는 변화의 시기로 유형 II III이 혼재되어 있다. 유형을 크게 3가지로 구분하였으나 유형 II III은 각이 2개인 측면에서 그 형태가 유사하다고 볼 때 주목할 만한 전환기는 16세기 중반이라고 볼 수 있다. 아마도 유형 I은 유형 II III에 비해 제작 과정상 공이 더 많이 들어갈 것으로 생각되며, 후대로 내려올수록 경제성의 원리에 따라 삽의 형태 및 제작방법도 간소해진 것으로 보인다. 상장례의 간소화 경향은 "선조실록(宣祖實錄)"에 예장(禮葬)이 몇 차례 중지되는 사건들을 통해 임진왜란 이후에 가속화된 변화로 볼 수 있다. 삽의 경우 이미 16세기 후반부터 간소화되고 있었으며, 심지어 18세기에는 삽을 따로 제작하지 않고 구의(柩衣) 및 관(棺)에 직접 그리는 현상까지 초래하였다. 그러나 형태적으로 단순화 되는 과정에도 "례기(禮記)"의 삽 사용 규정은 지켜지고 있어, 그 의례의 형식은 합리적으로 간소화되었음을 알 수 있다.