• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.3
• /
• pp.486-495
• /
• 2006

In this paper, a low-power 1Kb synchronous EEPROM is designed with flash cells for passive UHF RFID tag chips. To make a low-power EEPROM, four techniques are newly proposed. Firstly, dual power supply voltages VDD(1.5V) and VDDP(2.5V), are used. Secondly, CKE signal is used to remove switching current due to clocking of synchronous circuits. Thirdly, a low-speed but low-power sensing scheme using clocked inverters is used instead of the conventional current sensing method. Lastly, the low-voltage, VDD for the reference voltage generator is supplied by using the Voltage-up converter in write cycle. An EEPROM is fabricated with the $0.25{\mu}m$ EEPROM process. Simulation results show that power dissipations are $4.25{\mu}W$ in the read cycle and $25{\mu}W$ in the write cycle, respectively. The layout area is $646.3\times657.68{\mu}m^2$.

• Communications for Statistical Applications and Methods
• /
• v.15 no.4
• /
• pp.563-585
• /
• 2008

This paper presents how to improve the efficiency and accuracy in the pricing and sensitivity evaluation for derivatives, since the need for the evaluation of complicated derivatives is increased. The Monte Carlo(MC) simulation using the quasi random number instead of pseudo random number can improve the elapsed time and accuracy for the valuation of European-type derivatives. However, the quasi MC simulation method has its limit for applying it in the multi-dimensional case such as American-type and path-dependent options due to the increased correlation between dimensions as the dimension of random numbers is increased. In order to complement this problem, we develop a modified method in which correlation values are controlled to be below a pre-specified value. Thus, this method is applicable for the pricing of either derivatives ill which underlying assets or risk factors are several or derivatives having path-dependent or early redemption property. Furthermore, we illustrate that it is important to take an appropriate grid interval for the use of finite difference method(FDM) by applying the FDM to one example of non-symmetrical butterfly spreads.

• Journal of Korean Society of Transportation
• /
• v.32 no.5
• /
• pp.531-543
• /
• 2014

Research on activity-based travel demand forecasting and activity-travel simulator has received an international attention for the last two decades. Ways to develop the activity-based simulator may be manifold. It is obvious that importing an existing simulator that has been proven internationally likely reduces the development cost and the risk of failure. By definition of the activity-based approach, however, the details of an activity-based simulator inevitably relies on particular social, economic and cultural characteristics of the society where the simulator is developed. When importing such a simulator from overseas, the researcher should be aware of the importance of tuning the system for the society to which the imported system is applied. There are many potential works on this, including for example the tuning of data structure that is likely different form of the original system. The authors are yet aware of certain research on those. The current paper aims to report the result of transforming the input data for applying the existing activity-travel simulator to Seoul. The paper first introduces FEATHERS that was developed in Belgium having Albatross which is the core of system. FEATHERS Seoul that is under development and modified version of the original FEATHERS is briefly described and the related problems are discussed. The paper then explored to resolve and to alleviate such problems.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.24 no.3
• /
• pp.310-320
• /
• 2014

Backgrounds: Endotoxin, which found in the outer membrane of the gram-negative bacteria cell wall, makes up almost all of the lipopolysaccharide(LPS). When people are exposed to endotoxin,it can result in diverse health effects such as an airway irritation and inflammation, fever, malaise, bronchitis, allergic asthma, toxic pneumonitis, hypersensitivity lung disease. Cases among the elderly, children or pregnant can occur more frequently than a healthy adult if they are repeatedly exposed to the existing endotoxin. Therefore, we investigated and assessed the environmental characteristics associated with the airborne endotoxin concentration level in six hospital lobbies. Method: Endotoxin from indoor air in six hospital lobbies was measured by an area sampling method and analyzed according to American Society for Testing and Materials International(ASTM international) E2144-01. Total suspended particulate(TSP), carbon dioxide($CO_2$), temperature and humidity were also measured by using direct reading measurements or airborne sampling equipment at the same time. Environmental characteristics were appropriately divided into two or three groups for a statistics analysis. One-way analysis variable(one-way ANOVA) was used to examine a difference of the endotoxin concentration, depending on the environmental characteristics. In addition, only variables with p-value(p<0.25) were eventually designed to the best model by using multiple regression analysis. Results: The correlation analysis result indicated that TSP(p=0.003) and $CO_2$(p<0.0001) levels were significantly associated with endotoxin concentration levels. In contrast, temperature(p<0.068) and humidity(p<0.365) were not associated with endotoxin concentration. Levels of endotoxin concentration were statistically different among the environmental characteristics of Service time(p=0.01), Establishment of hospital(p<0.001), Scale of hospital(p=0.01), Day average people using hospital(p=0.03), Cleaning time of lobby(p=0.05), Season(p<0.001), and Cleaning of ventilation system(p<0.001) according to ANOVA. Finally, the best model(Adjusted R-square=72%) that we designed through a multiple regression test included environmental characteristics related to Service time, Area of lobby, Season, Cleaning of ventilation system, and Temperature. Conclusions: According to this study, our result showed a normal level of endotoxin concentration in the hospital lobbies and found environmental management methods to reduce the level of endotoxin concentration to a minimum. Consequently, this study recognized to be requirement for the management of ventilation systems and an indoor temperature in order to reduce the level of endotoxin concentration in the hospital lobbies.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.898-904
• /
• 2003

This study was conducted to observe the effect of various kinds of sugars and their molar concentrations on the Maillard browning reaction. To observe the effects of various kinds of sugar, glucose, fructose, tagatose, xylose, and sucrose were employed. A model solution consisting of 0.2 M sugar and 0.2 M glycine was prepared and heated at $100^{\circ}C$ for 5 hr. The model solution with adjusted concentrations of either tagatose or glycine was also heated at $100^{\circ}C$ for 5 hr. Tagatose showed the fastest Maillard reaction, followed by xylose, fructose, glucose, and sucrose. After glycine concentration of the model solution was fixed, the model solution showed more browning with an increase in tagatose concentration. When the tagatose concentration of the model solution was fixed, the model solution showed more browning with an increase in glycine concentration. The model solution with a fixed concentration of glycine showed more more browning than that with a fixed concentration of tagatose, since the former had higher amounts of the reactant.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.1
• /
• pp.20-26
• /
• 2015

Ceramic ink-jet printing technology in art tiles, decorated tablewares and other porcelain products has many advantages of fast and precision printing of various images with high efficiency and low cost. For the application to ink-jet printing, ceramic ink requires a stable dispersibility with nano-sized pigments. In this paper, characteristics of pink-red aqueous ceramic ink for ink-jet printing was demonstrated. $CaCr_{0.1}Sn_{0.8}SiO_5$ pigment was synthesized using solid state reaction and deagglomerated using attrition milling. The aqueous ceramic ink contains 10 wt% of the obtained $CaCr_{0.1}Sn_{0.8}SiO_5$ nanopigment with 0.4 wt% of sodium dodecyl sulfate (SDS) as a dispersion agent. Viscosity of $CaCr_{0.1}Sn_{0.8}SiO_5$ aqueous ceramic ink was adjusted using 0.18 wt% of polyvinyl alcohol (PVA) for a suitable jetting from the nozzle. The prepared pink-red ceramic ink showed a good jetting property with formation of a single sphere-shaped droplet after $180{\mu}s$ without a tail and satellite droplet.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.27 no.3
• /
• pp.122-129
• /
• 2017

For the production of a high-density ITO target, $In_2O_3$ powders with a small particle size and low agglomeration should be synthesized. The purpose of this study is to control the size and shape of the Indium hydroxide precursor which affects the properties of the $In_2O_3$ powder. As a starting raw material, Indium metal was dissolved in a Nitric acid ($HNO_3$) solution. The effect of concentration, pH, and temperature on the properties of Indium hydroxide was investigated using ammonium hydroxide as a precipitant. Crystallite size of each sample was analyzed by X-ray diffraction and the shape and the size of the powder was analyzed by transmission electron microscopy. As a result, the particle size of Indium hydroxide was increased with increase in the concentration of $In(NO_3)_3$ and the particle size and shape of the Indium hydroxide remained unchanged with increase in the pH of the solution. The particle size increased with increase in the precipitation temperature during precipitation.

• Composites Research
• /
• v.27 no.5
• /
• pp.183-189
• /
• 2014

Experimental considerations have been performed to obtain the clear optical microscopic images of graphene oxide which are useful to probe its quality and morphological information such as a shape, a size, and a thickness. In this study, we investigated the contrast enhancement of the optical images of graphene oxide after hydrazine vapor reduction on a Si substrate coated with a 300 nm-thick $SiO_2$ dielectric layer. Also, a green-filtered light source gave higher contrast images comparing to optical images under standard white light. Furthermore, it was found that a image channel separation technique can be an alternative to simply identify the morphological information of graphene oxide, where red, green, and blue color values are separated at each pixels of the optical image. The approaches performed in this study can be helpful to set up a simple and easy protocol for the morphological identification of graphene oxide using a conventional optical microscope instead of a scanning electron microscopy or an atomic force microscopy.

• Korean Journal of Occupational Health Nursing
• /
• v.17 no.1
• /
• pp.23-33
• /
• 2008

Purpose: The purpose of the study was to identify attitudes of middle managers toward employees with psychological problems and to determine factors affecting their attitudes. Methods: A questionnaire with Community Attitudes Toward Mentally Ill (CAMI) scales was administered to 161 middle managers working in small and medium-sized enterprises based in Seoul and Gyeonggi Province. Results: There are four separate subscales on the CAMI. Mean score for authoritarianism was $35.0{\pm}4.4$, benevolence $23.0{\pm}4.8$, social restrictiveness $32.3{\pm}4.9$ and community mental health ideology $27.2{\pm}5.1$ According to multiple regression analysis, middle managers with no experience of learning mental illness through mass media or higher levels of depression symptom were more authoritative and less benevolent towards employees with psychological problems. The experience of meeting a patient with mental problem contribute to positive attitudes toward people with mental illnesses in social restrictiveness subscale and community mental health ideology subscale among CAMI. Conclusion: This study suggests that experience of having patients with mental problems and information on psychological problems will have great influence on attitudes of middle managers toward employees with psychological problems. It might be important to help middle manager manage their depression because their depression also affects their attitudes toward employees with psychological problems.

• Korean Journal of Health Education and Promotion
• /
• v.20 no.1
• /
• pp.41-60
• /
• 2003

This study, performed to analyze the factors associated with health and cancer screening using preventive programs form health insurance among the women of a community, through a survey of about 923 women in Euijungbu-city. The subjects of the study were selected by a proportional cluster sampling method. The self-reported questionnaire was intended to fine factors associated with health screening and cancer screening. The results of this study were as follows: 1. In the case of health screening using health insurance, 14.1% of the subjects turned out to have been screened once or more in their respective life-time. Reasons given for non-participation in the screening were : 'lacking screening information', a belief that' it's not useful' and a belief that they' weren't sick'. 2. The factors associated with health screening behavior were age, educational level, number of doctor visits, BMI and health promotion behavior(p<0.01, p<0.05). Also, the factors associated with health screening behavior were cue to action and health status, and the predictors on health screening behavior were age and health promotion behavior(p<0.01, p<0.05). 3. In the case of cancer screening through the health insurance, 7.4% of the subjects turned out to have been screened once or more respectively in their life-times. Reasons given for non-participation in the screening were : 'lacking screening information', a belief they 'weren't sick' and that it's not useful'. 4. The factors associated with cancer screening behavior were age, educational level, income, alcholol intake, exercise, number of doctor visits and BMI(p<0.01, p<0.05). Aditional factors associated with cancer screening behavior were cue to action, health belief score and health status. Predictors for cancer screening behavior were: age, health belief score, screening attitude and health status(p<0.01, p<0.05). As indicated by the above results, a lack of information was an important factor for a lack of participation in screening. Age and cue to action were also important factors in promoting the cancer screening rate. Therefore, a dissemination of information about cancer screening contributes to the promotion of a screening rate, and cooperation between health insurance and local health cancer facilitates to be public the community-based cancer screening program.