• Bulletin of the Korean Chemical Society
• /
• 제24권3호
• /
• pp.285-290
• /
• 2003

An analytical method for the simultaneous determination of trace Ge, As and Se in biological samples by inductively coupled plasma/mass spectrometry has been investigated. The effects of added organic gas into the coolant argon gas on the analyte signal were studied to improve the detection limit, accuracy and precision. The addition of a small amount of methane (10 mL/min.) into the coolant gas channel improved the ionization of Ge, As and Se. The analytical sensitivity of the proposed Ar/CH₄system was superior by at least two-fold to that of the conventional Ar method. In the present method, the detection limits obtained for Ge, As and Se were 0.014, 0.012 and 0.064 ㎍/L, respectively. The analytical reliability of the proposed method was evaluated by analyzing the certified standard reference materials (SRM). Recoveries of 99.9% for Ge, 103% for As, 96.5% for Se were obtained for NIST SRM of freeze dried urine sample. The proposed method was also applied to the biological samples.

• 산업공학
• /
• 제13권4호
• /
• pp.658-667
• /
• 2000

Seasonal variation of natural gas demand coupled with rigid and stable import pattern of gas represents the characteristic feature of the Korean Liquified Natural Gas(LNG) industry. This attribute has required a huge amount of investment for the construction of storage facility. Thus, to minimize the supply cost, it is legitimate to reduce storage requirement itself. In this study, we combine three alternative methods to deal with the storage requirement to minimize the supply cost. Those are (1) adding additional storage tanks, (2) inducing large firm customers, and (3) constructing gas-turbine self generation facilities. Methodologically, we employ the mixed integer program (MIP) to optimize the system. The model also consider demand and price-setting scheme in separate modules. From the results, it is shown that if alternatives are combined optimally, a number of storage tanks can be reduced substantially compared with the original capacity plan set by the industry authorities. We perform various sensitivity analyses to check the robustness of the results. The methodology presented in this study can be applied to the other physical network industry, such as hydraulics. The empirical results will shed some light on the rationalization of capacity planning of the Korean natural gas industry.

• 산업공학
• /
• 제18권2호
• /
• pp.136-147
• /
• 2005

This paper introduces a simulation study regarding the operation of the Painted Body Storage (PBS) in an automobile factory. In the paint shop of the factory, same colored bodies are grouped together in order to increase the effectiveness of process, for example decrease the loss of cleaning the painting-gun when the color of body changes from one to another. However the production of automobiles in the assembly shop is a typical example of the mixed model assembly production. Therefore PBS locates between the paint shop and the assembly shop for control the input sequence of bodies to the assembly shop, and it enables to meet the smoothing requirement of assembly sequence. There are highly restricted constraints on the assembly sequence in a assembly shop. Those are spacing restriction and smoothing restriction. If such restrictions are violated, conveyor-stop or utility work will be necessary. Thus the major objective of PBS is to control the assembly sequence in a way to meet the two restrictions. In this paper a case study of PBS in an automotive factory is introduced. The storage/retrieval algorithms are suggested and the proposed system is verified using simulation models. Sensitivity analysis for operating factors is also conducted.

• 한국동물위생학회지
• /
• 제23권2호
• /
• pp.137-142
• /
• 2000

In order to develop a good separation and simultaneous analysis of different sugar in an artificial mixed sugar solution, we analyzed 10 sugar components in an artificial mixed sugar solution composed of fructose, glucose, mannitol, sucrose, maltose, lactose, xylose, xylitol erythritol, and trehalose with using HPLC-ELSD or HPLC-RI. Separation and quantification by HPLC-ELSD was superior to those by HPLC-RI and detection sensitivity by HPLC-ELSD was higher then that by HPLC-RI as micorgram($\mu\textrm{g}$) level. 1. The units of minimal detectable limits were showed $\mu\textrm{g}$/$m\ell$ and ng/$m\ell$ by the HPLC-RI and HPLC-ELSD, respectively. 2. The condition of ELSD was drift tube temperature $82^{\circ}C$, $N_2$ gas flow rate 2.10 SLPM, and colum oven temperature $30^{\circ}C$, respectively. Isolation and recovery rates of single sugar from the multiple sugar solution was higher at the condition (time: flow rate: D.W.:ACN MeOH, min : $m\ell$/min:v:v:v) of linear gradient elution of mobile phase as 0 : 1.00 : 15 : 85 : 0.1 : 1.00 : 6 : 90 : 4, 17 : 1.00 : 10 : 70 : 20, 28 : 1.00 : 15 : 85 : 0 an 35 : 1.00 : 15 : 85 : 0, in order.

• 한국재료학회지
• /
• 제34권5호
• /
• pp.235-241
• /
• 2024

Gas identification techniques using pattern recognition methods were developed from four micro-electronic gas sensors for noxious gas mixture analysis. The target gases for the air quality monitoring inside vehicles were two exhaust gases, carbon monoxide (CO) and nitrogen oxides (NO_x), and two odor gases, ammonia (NH₃) and formaldehyde (HCHO). Four MEMS gas sensors with sensing materials of Pd-SnO₂ for CO, In₂O₃ for NO_X, Ru-WO₃ for NH₃, and hybridized SnO₂-ZnO material for HCHO were fabricated. In six binary mixed gas systems with oxidizing and reducing gases, the gas sensing behaviors and the sensor responses of these methods were examined for the discrimination of gas species. The gas sensitivity data was extracted and their patterns were determined using principal component analysis (PCA) techniques. The PCA plot results showed good separation among the mixed gas systems, suggesting that the gas mixture tests for noxious gases and their mixtures could be well classified and discriminated changes.

• Parasites, Hosts and Diseases
• /
• 제56권1호
• /
• pp.61-70
• /
• 2018

We developed a Rapid Diagnostic Test (RDT) kit for detecting IgG/IgM antibodies against Zika virus (ZIKV) using monoclonal antibodies to the envelope (E) and non-structural protein 1 (NS1) of ZIKV. These proteins were produced using baculovirus expression vector with Sf9 cells. Monoclonal antibodies J2G7 to NS1 and J5E1 to E protein were selected and conjugated with colloidal gold to produce the Zika IgG/IgM RDT kit (Zika RDT). Comparisons with ELISA, plaque reduction neutralization test (PRNT), and PCR were done to investigate the analytical sensitivity of Zika RDT, which resulted in 100% identical results. Sensitivity and specificity of Zika RDT in a field test was determined using positive and negative samples from Brazil and Korea. The diagnostic accuracy of Zika RDT was fairly high; sensitivity and specificity for IgG was 99.0 and 99.3%, respectively, while for IgM it was 96.7 and 98.7%, respectively. Cross reaction with dengue virus was evaluated using anti-Dengue Mixed Titer Performance Panel (PVD201), in which the Zika RDT showed cross-reactions with DENV in 16.7% and 5.6% in IgG and IgM, respectively. Cross reactions were not observed with West Nile, yellow fever, and hepatitis C virus infected sera. Zika RDT kit is very simple to use, rapid to assay, and very sensitive, and highly specific. Therefore, it would serve as a choice of method for point-of-care diagnosis and large scale surveys of ZIKV infection under clinical or field conditions worldwide in endemic areas.

• 한국가스학회지
• /
• 제13권2호
• /
• pp.23-29
• /
• 2009

Pt, Pd, In 등의 촉매금속을 사용하여 아세토나이트릴 유독가스에 대한 감도를 향상시키는 SnO2 가스센스에 대하여 연구하였다. Metal-SnO2 후막은 백금전극이 내장된 알루미나 지지체의 스크린법으로 제작되었다. 본 센서의 특성은 검출가스의 농도의 함수로 반응기내 각센서의 전기적 저항을 측정하여 조사하였으며, 10-50ppm 범위의 유독가스 농도에 대하여 검지 측정하였다. 그 결과 촉매금속의 종류에 따라 센서에서 반응하는 감도가 각각 다르게 선택성을 갖고 있는 것으로 나타났다.

• Communications for Statistical Applications and Methods
• /
• 제18권1호
• /
• pp.57-69
• /
• 2011

질병에 대한 새로운 진단검사 방법이 의학 연구자들에 의해 끊임없이 개발되고 있으며, 기존 진단검사 방법과 새로운 진단검사 방법을 비교하는 연구논문이 계속 출간되어 누적되고 있다. 메타분석법으로 다수 연구논문의 결과를 종합하여 정확성이 높은 진단검사에 대해 객관적인 결론을 내리게 된다. 이와같이 출간된 두 진단검사를 비교하는 각 연구논문은 각각 질병을 가진 개체와 질병을 가지지 않은 개체에 두 검사를 모두 실시하여 한 쌍의 민감도와 특이도를 구하여 비교한다. 이러한 연구논문의 결과를 종합하는 메타분석은 동일 개체에 실시한 두 검사로 인해 한 쌍의 민감도간의 연관성과 한 쌍의 특이도 간의 연관성을 고려한 메타분석법을 본 논문에서 제시한다. 논문예제 자료와 모의시험으로 메타분석 검정통계량의 효율성을 평가한다.

• Journal of Community Nutrition
• /
• 제4권3호
• /
• pp.143-150
• /
• 2002

The objective of this study is to establish outcome validity for three instruments that assess whether subjects met recommendations for daily servings of fruits and vegetables for“Stage of Change”research. A convenience sample of 294 college students was recruited from introductory nutrition classes at Michigan State University in the United States. To measure servings of fruits and vegetables, separately, three types of methods (self-rated intake, 24-hour recall and food frequency) were used in comparison to the servings from a three-day food record, the criterion used. The outcome validity was assessed based on whether or not at least two servings of fruits and three servings of vegetables were reported. Validity was assessed by sensitivity, to measure the ability to detect low intakes, and by specificity, to measure ability to detect adequate intakes. Cohen's kappa was used as well to examine the agreement between the three methods and a three-day food record. The results showed, for fruits, the 24-hour recall had the best agreement (recall 0.54, self-rated : 0.31, food frequency : 0.29) with a three-day food record for servings consumed by people in pre-action or post-action stages. Sensitivity for fruit was also best using a recall (0.81). For vegetables, however, all three methods had low agreement (food frequency : 0.27, recall : 0.21, self-rated : 0.17) with the results of the three-day food record. Self-rated intakes for vegetables had the best sensitivity (0.66) and the food frequency had the best specificity (0.73). Therefore, researcher can use the 24-hour recall method to identify people who consume inadequate servings of fruit. To detect adequate vegetable intake, the food frequency was best of the three methods. Accuracy may be improved by probing for vegetables in mixed dishes and on sandwiches. (J Community Nutrition 4(3)： 143∼150, 2002)

• Parasites, Hosts and Diseases
• /
• 제52권4호
• /
• pp.377-381
• /
• 2014

Microscopy is considered as the gold standard for malaria diagnosis although its wide application is limited by the requirement of highly experienced microscopists. PCR and serological tests provide efficient diagnostic performance and have been applied for malaria diagnosis and research. The aim of this study was to investigate the diagnostic performance of nested PCR and a recently developed an ELISA-based new rapid diagnosis test (RDT), NovaLisa test kit, for diagnosis of malaria infection, using microscopic method as the gold standard. The performance of nested-PCR as a malaria diagnostic tool is excellent with respect to its high accuracy, sensitivity, specificity, and ability to discriminate Plasmodium species. The sensitivity and specificity of nested-PCR compared with the microscopic method for detection of Plasmodium falciparum, Plasmodium vivax, and P. falciparum/P. vivax mixed infection were 71.4 vs 100%, 100 vs 98.7%, and 100 vs 95.0%, respectively. The sensitivity and specificity of the ELISA-based NovaLisa test kit compared with the microscopic method for detection of Plasmodium genus were 89.0 vs 91.6%, respectively. NovaLisa test kit provided comparable diagnostic performance. Its relatively low cost, simplicity, and rapidity enables large scale field application.