• School Mathematics
• /
• v.18 no.2
• /
• pp.257-275
• /
• 2016

The purpose of this study was to investigate the impact of multiple representations on students' understanding of fractions, decimals, and percent. The instructional approach integrating multiple representations was compared to traditional algorithmic instruction, a form of direct instruction. To examine and compare the impact of multiple representations instruction with traditional algorithmic instruction, pre and post tests consisting of five similar items were administered with 87 middle school students. Students' scores in these two tests and their problem solving processes were analyzed quantitatively and qualitatively. The quantitative results indicated that students taught by traditional algorithmic instruction showed higher scores on the post-test than students in the multiple representations group. Furthermore, findings suggest that instruction using multiple representations does not guarantee a positive impact on students' understanding of mathematical concepts. Qualitative results suggest that the limited use of multiple representations during a class may have hindered students from applying their use in novel problem situations. Therefore, when using multiple representations, teachers should employ more diverse examples and practice with multiple representations to help students to use them without error.

• KSBB Journal
• /
• v.21 no.3
• /
• pp.212-219
• /
• 2006

The purpose of this study was to develop a assay system of host cell-derived residual proteins in final pharmaceutical products. Accurate and simple assay system for host cell-derived proteins(HCPs) is very important test item in pharmaceutical qualification control. In this study, methods for quantification of residual HCPs in recombinant anti-GPIIbIIIa antibody were developed using a process-specific immunoligand assay which was based on the Enzyme linked Immunosorbent assay(ELISA) system. The assay had a detection limit of 10.8 ng/ml of HCPs with a product concentration of 1 mg/ml. The practical implication of these results is that the developed ELISA system can be used for HCPs qualification control and this system will be applicable to develop another ELISA system of different antibody drug.

• Archives of Plastic Surgery
• /
• v.34 no.4
• /
• pp.432-435
• /
• 2007

Purpose: The jejunal free flap has the shorter ischemic time than other flap and requires a laparotomy to harvest it. As the evaluation of the perfusion the buried flap is very important, the perfusion of the buried jejunal free flap requires monitoring for its salvage. We tried to improve the monitoring flap method in the jejunal free flap and examined its usefulness. Methods: From March 2002 to March 2006, the monitoring flap method was applied to 4 cases in 8 jejunal free flaps for the pharyngeal and cervical esophageal reconstructions. The distal part of the jejunal flap was exposed without suture fixation through cervical wound for monitoring its perfusion. The status of perfusion was judged by the color change of jejunal mucosa and mesentery. If necessary, pin prick test was performed. Doppler sonography was applied to mesenteric pedicle of the monitoring flap in case of suspicious abnormal circulation. Results: The monitoring flap shows no change in 3 cases, but the congestion happened in one case at the 12 hours after the operation. This congestion was caused by the twisting or kinking of the mesenteric pedicle of the monitoring flap. So, we fixed up the monitoring flap close to adjacent cervical skin for prevention of rotation. Finally, the main part of transferred jejunal flap was intact. Conclusion: The success of a jejunal free flap depends on close postoperative monitoring and early detection of vascular compromise. So, various monitoring methods have been tried, for instance, direct visualization using a fiberoptic pharyngoscope, through a Silastic window placed in the neck flap, or external surface monitoring with an Doppler sonography, use of a buried monitoring probe. But, all of the above have their own shortcomings of simplicity, non-invasiveness, reliability and etc. In our experience, monitoring flap can be a accurate and reliable method.

• Korean Journal of Microbiology
• /
• v.38 no.3
• /
• pp.205-212
• /
• 2002

This study was conducted to develop a method for direct determination of phagocytic activities in human circulatic systems and to measure the phagocytic activities in human leukocytes from the alcoholics, since phagocytic activity was considered to be very important in human immune mechanism at early stage for the health care of the alcoholics. The subjects for this study were 130 among which 95 males and 3 females were diagnosed as alcoholism and 32 was healthy blood donors. A thin layer of heat-killed Staphylococcus aureus Cowan I was placed on a plastic dish and reacted with whole blood to measure the phagocytic plaque formation by human leukocytes. In order to determine the health conditions of the subjects, some clinical laboratory tests, such as white blood cell counts, hemoglobin contents (Hgb), mean corpuscular volume of red blood cells(MCV), serum electrophoresis, B and T-lymphocytes, T-lymphocyte subtypes and phytohemagglutination test were also implemented. Compared to the non-alcoholism, new and old alcoholic inpatients showed statistically significant differences on levels of Hgb and MCV (p<0.05), but showed that T and B-lymphocyte numbers decreased and Helper T cell/Suppressor T cell ratio ($1.6{\pm}0.8$%) increased. Compared to non-alcoholism, phagocytic plaque activities of leukocytes from alcoholic patients decreased significantly and an unusual pattern in phagocytic plaque was observed, showing a strange body and chain shaped phagocytosis. Based upon these results, it is concluded that a phagocytic-plaques of Staphylococcus aureus Cowan I by leukocytes was very simple and useful method for the early immunological determination of phagocytic activities in alcoholic patients without requiring any special equipments.

• Conservation Science in Museum
• /
• v.3
• /
• pp.71-78
• /
• 2001

The airtightness of museum cases in museums was measured by using CO₂ tracing gas, but it has been pointed that it has a problem with measuring the airtightness of a museum case which has a hole inside before it is used or while is being used. So studies tried to come up with alternatives which make it possible to measure the airtightness of a museum case before it is used or while it is being used if necessary by indirectly measuring the airtightness of the museum case without changing its form. Indirect measuring is done by measuring the change of Art-sorb weight and the change of temperature and humidity inside the museum case. Experiments were made for 12 days with three builtin wall case installed at the same place without turning on the lights but with Art-sorb and the data logger of temperature and humidity put into museum case. The change rate was produced with the change of temperature and humidity inside the museum case divided by that of those around museum case. As a result, the temperature change rate of museum case A(0.67) was lower than that of museum case B(0.69) or museum case C(0.79). The humidity change rate of museum case A(0.12) was lower than that of museum case B(0.19) or museum case C(0.72) showing that its airtightness was the best. Also in the direct airtightness measurement by CO₂ tracing gas, the air exchange rate was compared with the humidity change rate by Art-sorb in the indirect measurement.

• Tunnel and Underground Space
• /
• v.17 no.3 s.68
• /
• pp.203-215
• /
• 2007

Stability and mechanical deformation behavior of rock masses are highly dependent on the mechanical characteristics of contained discontinuities. Therefore, mechanical characteristics of the discontinuities should be considered in the design of tunnel and underground structures. In this study, direct shear tests for rough granite joints were carried out under constant normal stiffness conditions. Effects of initial normal stress, shear velocity, and surface roughness on the characteristics of shear strength and deformation behaviors were examined. Results of shear testing under constant normal stiffness conditions reveal that shear behaviors could be classified into two categories, based on the amount of decrease in shear stress at the Int peak shear stress. With initial normal stiffness increasing, it turned out that shear displacement at peak stress and the first peak shear stress increased, however friction angle and friction coefficient showed decrease. In case of shear stiffness and average friction coefficient, it turned out that they are not dependent on the initial normal stress. Minor effects of shear velocity on rough joints were observed in several shear quantities. However, the effects of shear velocity were insignificant regardless of the normal stress increase. Change of shear strength and deformation characteristics on joint roughness were examined, however, it turned out that the variations were attributed to deviation of shear test specimens.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.27 no.1
• /
• pp.38-45
• /
• 2017

Objectives: Radon may be second only to smoking as a cause of lung cancer. Radon is a colorless, tasteless radioactive gas that is formed via the radioactive decay of radium. Therefore, radon levels can build up based on the amount of radium contained in construction materials such as phospho-gypsum board or when ventilation rates are low. This study provides our findings from evaluation of radon gas at facilities and offices in an industrial complex. Methods: We evaluated the office rooms and processes of 12 manufacturing factories from May 14, 2014 to September 23, 2014. Short-term data were measured by using real-time monitoring detectors(Model 1030, Sun Nuclear Co., USA) indoors in the office buildings. The radon measurements were recorded at 30-minute intervals over approximately 48 hours. The limit of detection of this instrument is $3.7Bq/m^3$. Also, long-term data were measured by using ${\alpha}-track$ radon detectors(${\alpha}-track$, Rn-tech Co., Korea) in the office and factory buildings. Our detectors were exposed for over 90 days, resulting in a minimum detectable concentration of $7.4Bq/m^3$. Detectors were placed 150-220 cm above the floor. Results: Radon concentrations averaged $20.6{\pm}17.0Bq/m^3$($3.7-115.8Bq/m^3$) in the overall area. The monthly mean concentration of radon by building materials were in the order of gypsum>concrete>cement. Radon concentrations were measured using ${\alpha}-track$ in parallel with direct-reading radon detectors and the two metric methods for radon monitoring were compared. A t-test for the two sampling methods showed that there is no difference between the average radon concentrations(p<0.05). Most of the office buildings did not have central air-conditioning, but several rooms had window- or ceiling-mounted units. Employees could also open windows. The first, second and third floors were used mainly for office work. Conclusions: Radon levels measured during this assessment in the office rooms of buildings and processes in factories were well below the ICRP reference level of $1,000Bq/m^3$ for workplaces and also below the lower USEPA residential guideline of $148Bq/m^3$. The range of indoor annual effective dose due to radon exposure for workers working in the office and factory buildings was 0.01 to 1.45 mSv/yr. Construction materials such as phospho-gypsum board, concrete and cement were the main emission sources for workers' exposure.

• Korean Journal of Plant Tissue Culture
• /
• v.24 no.3
• /
• pp.129-135
• /
• 1997

Morphogenetic responses were investigated by culturing embryo and leaf explants of Korean wild type tea plant, Camellia sinensis (L.) O. Kuntze. Induction of direct somatic embryogenesis as well as adventitious and/or axillary shoots was obtained from mature zygotic embryo cultures on Murashige and Skoog (MS) basal medium having 5 to $20\mu\textrm{M}$cytokinin a lone. Morphogenetic response was decreased dramatically by the addition of auxins tested. One hundred percent of induced and isolated shoots formed roots after four weeks of culture on half-strength MS or quarter-strength Schenk and Hildebrandt (SH) media supplemented with $10\mu\textrm{M}$indole-3-butyric acid (IBA). Immature zygotic embryos were shown to be a suitable explant for embryogenic callus formation in the presence of 2, 4-dichlorophenoxyacetic acid(2, 4-D) in basal medium. Mature zygotic embryo originated leaves were used to test their ability for mophogenesis by incorporating plant growth regulators such as IBA, naphthyl-1-acetic acid (NAA), and 6-benzylaminopurine (BAP). Apparently, the morphogenetic responses of the cultured explant sources on the types and/or levels of plant growth regulators tested were observed visually.

• Asia pacific journal of information systems
• /
• v.23 no.2
• /
• pp.41-66
• /
• 2013

IS outsourcing has an important meaning to the Korean SME's (Small and Medium Enterprises) which want to use the IS Services. The objective of this research is to manage IT risks occurred during IS outsourcing project process. This study tries to identify these risks using real option methodology. In order to perform this objective, this study set up the research model which is composed of two main concepts. The first one is the risk factors occurred during IS outsourcing project process: User's Risks, Supplier's Risks and Transaction's Risks. All of these risks are based on Transaction Cost Theory. The second one is the intention to get (or buy) Real Options to manage the risks. In the research model, two types of real option are included: option to abandon (put option) and option to defer (call option). This study uses questionnaires and statistics methodology (PLS) to analyze the hypotheses proposed in the research model. Compared with prior studies, this study is different in two ways. First, this study restricts the range of IT risks. Prior researches of IT Risk management in MIS area cover various range of IT risks, but this study focuses on the Korean SME's IT outsourcing risks on the basis of Transaction Cost Theory. This study tests the relationship between the risks and real option types. Second, this study tries to test the moderating effect of user's risks and supplier's risks on the relationship between transaction's risks and real option types. In IT outsourcing research area, almost studies focus on the direct relationships between IT risks and outsourcing success. But in reality, the co-relationship among IT risks may occur. There are some findings according to the research analysis. First, risks related with user's risks have strong causal relationships with the intention to get option to abandon (put) and option to defer. But risks related with supplier's risks have causal relationships only with option to abandon (put). Second, user's risks and supplier's risks have no moderating effect on the relationship between transaction's risks and real option types. According to the research results, this research have some important and interesting implications on the IS outsourcing business area. First, this study identifies the effective types of real option to minimize the risks occurred during the IT outsourcing projects. So IS outsourcing service users can manage (or minimize) effectively the risks, which occurred during outsourcing projects, using real options. Second, real option gives benefits to suppliers and users at the same time (i.e., win-win strategies between IS outsourcing service providers and users). Vendors (:IS outsourcing service providers) can offer users the real options which can minimize the occurrence of risks in time. "IN TIME" means that before the IS outsourcing project starts, vendors can offer users the opportunity to buy real options in appropriate prices to manage the possibility of the risks of IS outsourcing project. And users also have chance to minimize the IT outsourcing risks occurred during the project process using real options.

• Journal of Nutrition and Health
• /
• v.24 no.5
• /
• pp.442-449
• /
• 1991

Concentrations of iron. zinc, and copper were measured in human milk samples collected longitudinally from 21 highly selected. healthy lactating women. And the daily milk and trace elements intakes of 14 exclusively breastfed infants were determined by the test-wei-ghing procedure and the direct analysis of milk samples at 6 or 7weeks postpartum. Significant decreases in iron. zinc and copper were found with time postpartum. Iron contents decreased from 0.33$\mu\textrm{g}$/$m\ell$ at 2-5 days to o.21$\mu\textrm{g}$/$m\ell$ at 12weeks. Zinc concentrations also declined from 4.15$\mu\textrm{g}$/$m\ell$ in colostrum to 2.33$\mu\textrm{g}$/$m\ell$ in matured milk at 12 weeks. Mean copper levels of colostum, transitional. and matured milk were 0.21$\mu\textrm{g}$/$m\ell$, 0.34$\mu\textrm{g}$/$m\ell$, and 0.26$\mu\textrm{g}$/$m\ell$ respectively. Data indicated that the amount of milk ingested ranged from 432g/day to 1266g/day and the mean intake was 768g/day. Daily mean intakes for iron, zinc, and copper were 0.19mg, 2.10mg, and 0.15mq respectively.