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임업용 트랙터의 단위거리당 집재비(원/㎥/100m)산출을 위한 이론적 고찰
梁松鉉 동국대학교 생명자원과학대학 연습림 1995 연습림논문집 Vol.- No.4
Skidding cost can be divided into fix and variable contents normally. Fix cost stays constant under the same operation conditions. But variable cost has a proportional relationship with skidding distance. in the case of opening-up, the first step in the planning stage is to optimize the forest road density. The optimum forest road density satisfies the minimum skidding cost with minimum forest road density(construction cost of forest road). Therfore the variable cost in skidding operation takes a definite role in caculating optimum forest road density. In this paper, the theoretical examine was carried out, to establish the method of calculating variable cost per unit in skidding operations.
機械化 集材作業에 따른 適定 林道密度 算出에 關한 考察
梁松鉉 동국대학교 생명자원과학대학 연습림 1993 연습림논문집 Vol.- No.3
The objective of this study is to investigate the optimum forest road density under the actual circumstance of forestry in Korea. In order to analyze the optimum forest road density, this study made use of the method “minimizing the total cost”. In this analysis, only monetary aspect were taken into account. They are: cost for forest road construction and maintenance, and cost for skidding. The applied skidding methods were mobile cable crane(K300), forestry tractor(MBTrac) and plastic shute(Leykam Logline). The result of analysis, namely the optimum forest road density is 11.12m/ha. Besides the result of this calculation, it was recommended to reckon in the walking cost of forest work and management, and the reduction of forest area caused by laying out of forest roads.
액체크로마토그래프-탠덤질량분석기(LC-MS/MS)를 이용한 소변 내 D-, L- Lactate 분리 및 정량
문철진,양송현,Moon, Chul Jin,Yang, Song Hyun 대한유전성대사질환학회 2015 대한유전성대사질환학회지 Vol.15 No.2
사람의 신체내에서 주로 존재하는 lactate는 L-lactate로서 몇몇 선천성대사이상과 관련하여 증가된다. 최근 2형 당뇨병(type 2 diabetes)과 만성적인 염증성 위장질환(inflammatory bowel disease)과 관련하여 증가되는 D-lactate를 L-lactate와 분리해야 하는 요구도가 높아졌다. 이에 액체크로마토그래프-탠덤질량 분석기를 사용하여 소변 내 D-, L-lactate를 분리하는 방법을 확립하였으며, 분석시간과 정밀성, 정확성, 특이성 등에서 신뢰성 있는 방법임을 확인하였다. Purpose: Lactate has two optical isomers, L-lactate and D-lactate. In human L-lactate is the most abundant enantiomer of lactate. As plasma and urinary levels of L-lactate is associated with inherited metabolic disorders in general, D-lactate have been linked to the presence of diabetes and inflammatory bowel disease. Previously developed techniques have shown several limitations to further evaluate D-lactate as a biomarker for this condition. In this paper, we describe a highly sensitive, specific and fast liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of D-, L-lactate in urine. Methods: D- and L-lactate were quantified using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) with labelled internal standard. Samples were derivatized with (+)-O,O'-diacety-L-tartaric anhydride (DATAN) and seperated on a Poroshell 120 EC-C18 column. Results: Quantitative analysis of D-, and L-lactate was achieved successfully. Calibration curves were linear (r>0.999) over $0.5-100{\mu}g/mL$. Stabilities for samples were within the 10% varation. Inter- and Intra-day assay variations were below 10%. Conclusion: The presented method proved to be suitable for the quantitation of D- and L-lactate and opens the possibility to explore the use of D-lactate as a biomarker.
신생아의 출생 체중에 따른 혈액 여과지 17alpha-hydroxyprogesterone의 농도 분석 및 판정 기준 조정
박승만,권애린,양송현,박은아,최재황,황미정,남현경,이은희,Park, Seungman,Kwon, Aerin,Yang, Songhyeon,Park, Euna,Choi, Jaehwang,Hwang, Mijung,Nam, Hyeongyeong,Lee, Eunhee 대한유전성대사질환학회 2014 대한유전성대사질환학회지 Vol.14 No.2
The measurement of $17{\alpha}$-hydroxyprogesterone ($17{\alpha}$-OHP) in a dried blood spot on filter paper is an important for screening of congenital adrenal hyperplasia (CAH). Since high levels of $17{\alpha}$-OHP are frequently observed in premature infants without congenital adrenal hyperplasia, we evaluated cuts-off based on birth weight and performed validation. Birth weight and $17{\alpha}$-OHP concentration data of 292,204 newborn screening subjects in Greencross labopratories were analyzed. The cut-off values based on birth weight were newly evaluated and validated with the original data. The mean $17{\alpha}$-OHP concentration were 7.25 ng/mL in very low birth weight (VLBW) group, 4.02 ng/mL in low birth weight (LBW) group, 2.53 g/mL in normal birth weight (NBW) group, and 2.24 ng/mL in heavy birth weight (HBW) group. The cut-offs for CAH were decided as follows: 21.12 ng/mL for VLBW and LBW groups and 11.14 ng/mL for NBW and HBW groups. When applied new cut-offs for original data, positive rates in VLBW and LBW groups were decreased and positive rates in NBW and HBW groups were increased. The cut-offs based on birth weight should be used in the screening for CAH. We believe that our new cut-off reduce the false positive rate and false negative rate and our experience for cut-off set up and validation will be helpful for other laboratories doing newborn screening test.
Evaluation of Serum Cotinine Cut-Off to Distinguish Smokers From Nonsmokers in the Korean Population
고기웅,권민정,양송현,문철진,이은희,우희연,박효순 대한진단검사의학회 2016 Annals of Laboratory Medicine Vol.36 No.5
Background: Cotinine has been widely used as an objective marker to identify current smokers. We conducted this study to address the absence of Korean studies investigating the efficacy of immunoassays and liquid chromatography–tandem mass spectrometry (LC-MS/MS) for the detection of serum cotinine and to determine the optimal serum cotinine cut-off level for differentiating current smokers from nonsmokers. Methods: Serum specimens were obtained from 120 subjects. They were randomly chosen to represent a broad distribution of urine cotinine levels based on a retrospective review of questionnaires and results of urine cotinine levels. We determined serum cotinine levels using the IMMULITE 2000 XPi Immunoassay System (Siemens Healthcare Diagnostics Inc., USA) and LC-MS/MS (API-4000, Applied Biosystems, USA). Correlation was analyzed between IMMULITE serum cotinine, urine cotinine, and LC-MS/MS serum cotinine levels. ROC curve was analyzed to identify the optimal IMMULITE serum cotinine cut-off level for differentiating current smokers from nonsmokers. Results: IMMULITE serum cotinine levels correlated with both urine cotinine and LC-MS/MS serum cotinine levels, with correlation coefficients of 0.958 and 0.986, respectively. The optimal serum cotinine cut-off level for distinguishing current smokers from nonsmokers was 13.2 ng/mL (95.7% sensitivity, 94.1% specificity) using IMMULITE. Conclusions: This is the first study to investigate the use of LC-MS/MS for the measurement of serum cotinine and to determine the optimal serum cotinine cut-off level for the IMMULITE immunoassay. Our results could provide guidelines for differentiating current smokers from nonsmokers in the Korean population.