• Journal of the Korean Chemical Society
• /
• v.53 no.5
• /
• pp.491-498
• /
• 2009

The critical micelle concentration (CMC) and the counter ion binding constant (B) for the mixed micellizations of DBS (sodium dodecylbenzenesulfonate) with Brij 30 (polyoxyethylene(4) lauryl ether) and Brij 35 (polyoxyethylene (23) lauryl ehter) at 25 ${^{\circ}C}$ in pure water and in aqueous solutions of n-butanol were determined as a function of $\alpha$1 (the overall mole fraction of DBS) by the use of electric conductivity method. Various thermodynamic parameters (Xi, $\gamma$i, Ci, aiM, $\beta$, and ${\Delta}H_{mix}$) were calculated and compared for each mixed surfactant system by means of the equations derived from the nonideal mixed micellar model. There sults show that the molecules of DBS interact more strongly with Brij 35 than Brij 30 and that the DBS/Brij35 mixed system has greater negative deviation from the ideal mixed micellar model than the DBS/Brij 30mixed system.

• Journal of the Korean Chemical Society
• /
• v.48 no.3
• /
• pp.236-242
• /
• 2004

The critical micelle concentration (CMC) and the counterion binding constant (B) in a mixed micellar state of the Dodecylpyridinium chloride (DPC) with the Cetyldimethylethylammonium bromide (CDEAB) at 25$^{\circ}C$ in aqueous solutions of n-butanol were determined as a function of ${\alpha}_1$ (the overall mole fraction of DPC) by the use of electric conductivity method. Various thermodynamic parameters (($X_i,\;{\gamma}_i,\;C_i,\;a^M_i,\;{\beta},\;and {\Delta}H_{mix})$were calculated by means of the equations derived from the nonideal mixed micellar model. The effect of n-butanol on the mixed micellization of the DPC/CDEAB mixtures has been also studied by analyzing the measured and calculated thermodynamic parameters (CMC, B 및 $;{\Delta}G_o\;^m$).

• Nuclear Engineering and Technology
• /
• v.26 no.2
• /
• pp.212-224
• /
• 1994

A numerical method has been developed for studying the dynamics of a flexible cylinder in a coaxial cylindrical duct, immersed in inviscid flow. The unsteady inviscid fluid-dynamic force acting on the oscillating cylinder has been estimated more rigorously by means of a spectral collocation method without simplification of governing equations. This numerical approach is applicable to the system haying wider annular gap and/or shorter length of cylinder as compared to existing potential theory. The governing equation of the unsteady flow was obtained from Laplace equation. The equation of cylinder motion coupled with the fluid motion was discretized by Galerkin's method, from which the dynamic behaviour of the system has been evaluated. The effect of the length of the cylinder and the annular gap on the critical flour velocity, where the system loses stability by buckling, was investigated. To validate the numerical method, the potential flow theory developed by Hobson based on thin film approximation has been improved. Typical results of the present numerical theory on the dynamics and stability of the system are compared with those of available existing theory and the present approximate results. Good agreement was found between the results. It was also found that a nondimensional critical flow velocity becomes larger as increasing the annular gap and decreasing the length of cylinder.

• Journal of Environmental Impact Assessment
• /
• v.21 no.1
• /
• pp.71-80
• /
• 2012

Against the backdrop of the clear impact of climate change, it has become essential to analyze the influence of climate change and relevant vulnerabilities. This research involved evaluating the impact of heat waves in Seoul, from among many local autonomous bodies that are responsible for implementing measures on adapting to climate change. To carry out the evaluation, the A1B scenario was used to forecast future temperature levels. Future climate scenario results were downscaled to $1km{\times}1km$ to result in the incorporation of regional characteristics. In assessing the influence of heat waves on people-especially the excess mortality-we analyzed critical temperature levels that affect excess mortality and came up with the excess mortality. Results of this evaluation on the impact of climate change and vulnerabilities indicate that the number of days on which the daily average temperature reaches $28.1^{\circ}C$-the critical temperature for excess mortality-in Seoul will sharply increase in the 2050s and 2090s. The highest level of impact will be in the month of August. The most affected areas in the summer will be Songpa-gu, Gangnam-gu, and Yeongdeungpo-gu. These areas have a high concentration of residences which means that heat island effects are one of the reasons for the high level of impact. The excess mortality from heat waves is expected to be at least five times the current figure in 2090. Adaptation plan needs to be made on drawing up long-term adaptation measures as well as implementing short-term measures to minimize or adapt the impact of climate change.

• Progress in Superconductivity
• /
• v.14 no.1
• /
• pp.1-10
• /
• 2012

We fabricated a closed coils by using resistive-joint method and the joint resistance of the coils were estimated by field decay technique in liquid nitrogen. We used the Runge-kutta method for the numerical analysis to calculate the decay properties. The closed coil was wound by $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag tape. Both ends the tape were overlapped and soldered to each other. The current was induced in a closed coils by external magnetic flux density. Its decay characteristic was observed by means of measuring the magnetic flux density generated by induced current at the center of the closed coil with hall sensor. The joint resistance was calculated as the ratio of the inductance of the loop to the time constants. The joint resistances were evaluated as a function of critical current of loop, contact length, sweep time, and external magnetic flux density in a contact length of 7 cm. It was observed that joint resistance was dependent on contact length of a closed coil, but independent of critical current, sweep time, and external magnetic flux density. The joint resistance was measured to be higher for a standard four-probe method, compared with that for the field decay technique. This implies that noise of measurement in a standard four-probe method is larger than that of field decay technique. It was estimated that joint resistance was $8.0{\times}10^{-9}{\Omega}$ to $11.4{\times}10^{-9}{\Omega}$ for coils of contact length for 7 cm. It was found that 40Pb/60Sn solder are unsuitable for persistent mode.

• Journal of Trauma and Injury
• /
• v.21 no.1
• /
• pp.1-7
• /
• 2008

When man first walked on this planet, injury must have been a close encounter of the first kind. The outbreak of World War I, during a period of rapid scientific growth in the basic sciences, demonstrated the need to develop better methods of care for the wounded, methods that were later applicable to the civilian population. Trauma is a multisystem disease and, as such, benefits from almost any advance in medical science. As we learn more about the physiology and the biochemistry of various organ systems, we can provide better management for trauma victims. Improved imaging techniques, better appreciation of physiologic tolerance, and increased understanding of the side effects of specific surgical procedures have combined to reduce operative intervention as a component of trauma patient care. On the other hand, because of this rapid development of medical science, only a few doctors still have the ability to treat multisystem injuries because almost doctor has his or her specialty, which means a doctor tends to see only patients with diagnoses in the doctor's specialty. Trauma Surgeons are physicians who have completed the typical general surgery residency and who usually continue with a one to two year fellowship leading to additional board certification in Surgical Critical Care. It is important to note that trauma surgeons do not need to do all kinds of operations, such as neurosurgery and orthopedic surgery. Trauma surgeons are not only a surgeon but also general medical practitioners who are very good at critical care and coordination of patient. In order to achieve the best patient outcomes, trauma surgeons should be involved in prehospital Emergency Medical Services, the Trauma Resuscitation Room, the Operating Room, the Surgical Intensive Care and Trauma Unit, the Trauma Ward, the Rehabilitation Department, and the Trauma Outpatient Clinic. In conclusion, according to worldwide experience and research, the trauma surgeon is the key factor in the trauma care system, so the trauma surgeon should receive strong support to accomplish his or her role successfully.

• International Journal of Ocean System Engineering
• /
• v.2 no.2
• /
• pp.106-115
• /
• 2012

In the present study, TiN and CrN films were coated by arc ion plating equipment onto aluminum alloy substrate, A2024. The film thickness was about 4.65 ${\mu}m$. TiN and CrN films were analyzed by X-ray diffraction and energy dispersive X-ray equipments. The Young's modulus and the micro-Vickers hardness of aluminum substrate were modified by the ceramic film coatings. The difference in Young's modulus between substrate and coating film would affect on the wear resistance. The critical load, Lc, was 75.8 N for TiN and 85.5 N for CrN. It indicated from the observation of optical micrographs for TiN and CrN films that lots of cracks widely propagated toward the both sides of scratch track in the early stage of MODE I. TiN film began to delaminate completely at MODE II stage. The substrate was finally glittered at MODE III stage. For CrN film, a few crack can be observed at MODE I stage. The delamination of film was not still occurred at MODE II and then was happened at MODE III. This agrees with critical load measurement which the adhesive strength was greater for CrN film than for TiN film. Consequently, it was difficult for CrN to delaminate because the adhesive strength was excellent against Al substrate. The wear process, which the film adheres and the ball transfers, could be enhanced because of the increase in loading. The wear weight of ball was less for CrN than for TiN. This means that the wear damage of ball was greater for TiN than for CrN film. It is also obvious that it was difficult to delaminate because the CrN coating film has high toughness. The coefficient of friction was less for CrN coating film than for TiN film.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.366-376
• /
• 2019

Youth unemployment reached a record high in 2017, and business revitalization is emerging as a means of overcoming this situation. The number of venture companies and amounts of new venture investments are increasing year on year, and the government has upgraded Small and Medium Business Administration to the Ministry of SMEs and Startups. However, the success rate of startups is relatively poor. Over the past three years only 39.1% of Korean startups survived and 90% of companies failed in the Valley of Death phase. Survival this phase is critical for early startups, and thus, the amount and timing of investments are critical. Current models for establishing business startups do not effectively attract investments because they lack practical, corporate evaluation variables. In this paper, we develop a mixed process that incorporates the factors and business models focused on by venture capital investors. In addition, we compared our Death Valley Venture (DVV) process with current methods and provide an example of its application.

• Philosophy of Education
• /
• no.60
• /
• pp.93-116
• /
• 2016

In this research we analyze Sun Wen's revolution education from the perspective of chinese nationalism. Sun Wen instigated the revolution of 1911 and established the first Chinese republican government; his "three people's principles" played an important role in modern Chinese politics. Sun Wen tried to remind the people and make them conscious of their sovereignty through education. Critical of then-the feudalistic education, Sun Wen incorporated Western-modern education in to his philosophy of education, which then provided theoretical framework of the Chinese revolution. At the core of it was the so-called "advanced education", based on Chinese nationalism, which encourages people to fight for independence as well as national prosperity and defense. The advanced education consisted of "proclaim education" and "constructive education". The proclaim education was a means of disseminating revolutionary ideas through an armed struggle against Ching dynasty; the goal was to encourage people to participate actively. Constructive education could be divided into two periods, namely the period of pre-republic of China and post-republic of China; the aim and process of education in the former period was to "wipe out" the Manchu people of the Qing dynasty while in the latter, to build a country predicated on Chinese nationalism, which was hostile towards the Qing dynasty and any other thoughts that do not accord with it. The main purpose of revolution education was to inspire Sinocentrism and to solidify the country of the Chinese people. Ultimately, Sun Wen's philosophy of revolution education provided foundation for the construction of a country of the Chinese people in which inspirational writing for the welfare of the people, loyalty to country, and public service are realized.

• Korean Journal of Chemical Engineering
• /
• v.35 no.11
• /
• pp.2269-2282
• /
• 2018

Mixed micelle formation behavior of cationic surfactant-cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous as well as in urea medium from 303.15 K to 323.15 K at 5 K interval was carried out by conductometric method. The differences between the experimental values of critical micelle concentrations (cmc) and ideal critical micelle concentrations ($cmc^{id}$) illustrate the interaction between the amphiphiles studied. The values of micellar mole fraction ($X_1^{Rub}$ (Rubingh), $X_1^M$ (Motomura), $X_1^{Rod}$ (Rodenas) and $X_1^{id}$(ideal) of surfactant CTAB determined by different proposed models and outcome indicate high involvement of CTAB in SDS-CTAB mixed micellization, which enhance by means of the augment of mole fraction of CTAB. The negative value of interaction parameter (${\beta}$) showed an attractive interaction involving CTAB and SDS. Activity coefficients were less than unity in all case, which also reveals the presence of interaction between CTAB & SDS. The negative ${\Delta}G^0_m$ values imply the spontaneous mixed micellization phenomenon. The attained values of ${\Delta}H^0_m$ were positive at inferior temperature, while negative at superior temperature. The negative ${\Delta}H^0_m$ values in urea ($NH_2CONH_2$) medium illustrate exothermic micellization process. The magnitudes of ${\Delta}S^0_m$ were positive in almost all cases. The excess free energy of mixed micelle formation (${\Delta}G_{ex}$) was found to be negative, which indicates the stability of mixed micelle as compared to the individual's components micelles.