• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.101-109
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• 2005

The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by $1^{circ}C$, but the pressure loss of air side is much higher for type B by $29\%$. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.1-6
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• 1999

A piezoelectric (PZ) biosensor system detecting Salmonella spp. was developed. The system consisted of an oscillator, a frequency counter and an antibody-immobilized quartz crystal. An anti-Salmonella antibody was immobilized on one gold. surface of the quartz crystal with protein A. Salmonella detection was made by measuring resonant frequency shift owing to a mass change by specific binding of microbial cells to the gold surface of the PZ crystal. The PZ antibody sensor was operated optimally at 0.1M phosphate buffer, pH 7.2 and $35^{\circ}C$. The sensor was quite specific to Salmonella spp. The obtained frequency shift was correlated with the Salmonella concentration in the range of $10^5{\sim}10^6\;CFU/mL$. The frequency shift increased further by addition of polystyrene beads. The Salmonella detection which is indicated by a steady-state microbial adsorption to the quartz crystal was accomplished within 50min.

• Journal of the Korean housing association
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• v.20 no.6
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• pp.111-118
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• 2009

In modern Asia major cities had same problem with lack of affordable housing for families. So they had to concentrate to the mass supply of housing and made some physical counter effects like high density of cities, limitation of parking space. Also people who lived in those cities could suffer from broken traditional community culture. To rebuild traditional community and increase land usage, Block housing is suggested as a new kind of multi-family housing for old town redevelopment. Now some governments are trying to make urban code to give some initiative for new block housing development in old city blocks. They expect this new housing type can help to solve serious problems like lack of parking area, green space and context of block. Also they hope that block housing development can help to increase safety of town and reduce cost of development. The purpose of this study is to review the establishment and development process of Block Housing and to confirm the aspect which has been changed with urban organization together. Also this study tried to find out the intentional characteristics of similarities and differences with comparison of Korea and Japan. And as a result we could find critical physical viewpoint, and provide considerations for future study and plan. Several cases of block housing in Korea and Japan were reviewed for comparative study and Post Occupancy Evaluation (POE) survey was examined to find satisfaction factors and problems which were expected to improved.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.595-597
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• 2015

LMC X-4 is an eclipsing high-mass X-ray binary exhibiting a superorbital modulation with a period of ~ 30:5 days. We present a detailed study of the variations of the superorbital modulation period with a time baseline of ~ 18 years. The period determined in the light curve collected by the Monitor of All-sky X-ray Image (MAXI) significantly deviates from that observed by the All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE). Using the data collected by RXTE/ASM, MAXI, and the Burst Alert Telescope (BAT) onboard Swift, we found a significant period derivative, $\dot{P}=(2.08{\pm}0.12){\times}10^{-5}$. Furthermore, the O{C residual shows complex short-term variations indicating that the superorbital modulation of LMC X-4 exhibits complicated unstable behaviors. In addition, we used archive data collected by the Proportional Counter Array (PCA) on RXTE to estimate the orbital and spin parameters. The detected pulse frequencies obtained in small time segments were fitted with a circular orbital Doppler shift model. In addition to orbital parameters and spin frequency for each observation, we found a spin frequency derivative of $\dot{v}=(6.482{\pm}0.011){\times}10^{-13}Hz{\cdot}s^{-1}$. More precise orbital and spin parameters will be evaluated by the pulse arrival time delay technique in the future.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.132.2-132.2
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• 2012

We have investigated the characteristics of magnetic cloud (MC) and ejecta (EJ) associated coronal mass ejections (CMEs) based on the assumption that all CMEs have a flux rope structure. For this, we used 54 CMEs and their interplanetary counter parts (interplanetary CMEs: ICMEs) that constitute the list of events used by the NASA/LWS Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We considered the location, angular width, and speed as well as the direction parameter, D. The direction parameter quantifies the degree of asymmetry of the CME shape, and shows how closely the CME propagation is directed to Earth. For the 54 CDAW events, we found several properties of the CMEs as follows: (1) the average value of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49), which indicates that the MC-associated CMEs propagate more directly to the Earth than the EJ-associated CMEs; (2) comparison between the direction parameter and the source location shows that the majority of the MC-associated CMEs are ejected along the radial direction, while many of the EJ-associated CMEs are ejected non-radially; (3) the mean speed of MC-associated CMEs (946 km/s) is faster than that of EJ-associated CMEs (771 km/s). For seven very fast CMEs (>1500 km/s), all CMEs with large D (>0.4) are associated with MCs and the CMEs with small D are associated with EJs. From the statistical analysis of CME parameters, we found the superiority of the direction parameter. Based on these results, we suggest that the CME trajectory essentially decides the observed ICME structure.

• Convergence Security Journal
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• v.17 no.2
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• pp.127-135
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• 2017

Today, Kim Jong-un, the third-hereditary regime in North Korea, is committing Nuclear Provocation more aggressively than the past when Kim Il-sung and Kim Jong-il dominated. Past South Korea government had suggested plans to restrain the provocation from North Korea and bring stabilization in the Korean Peninsula. However, consequentially it was limited to the primary role of the President. When President Trump takes over the government in February 2017, it has attracted the expectation about the issues occurred on the Korean Peninsula due to the pledge that he promised during the presidential election and his govern style. However, various speeches about the Korean Peninsula that he spoke recently made situations depressed about what South Korean currently encounters. Furthermore, previous regime in North Korea has laid the foundation for Kim Jong-un to be obsessed more on the nuclear and missile which has led him to provoke more imprudently by highlighting the light weight, advanced, and various kinds of nuclear and missiles. Thus, we would like to propose counter measures in order for South Korean government to handle and solve the issues that they encounters by themselves based on North Korea's Nuclear Provocation instead of relying on other countries to get involved and help.

• Journal of Korean Public Health Nursing
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• v.26 no.1
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• pp.147-157
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• 2012

Purpose: The purpose of this study was to identify the related factors of change affecting the stages of change for exercise, on the assumption that there are various stages of change in the exercise behavior of women in nursing college. Methods: The subjects were 496 female college students in D city. The research instruments were stages of change for exercise behavior, the process of change, decisional balance, and self-efficacy. The dates were analyzed by descriptive statistics, ANOVA, and stepwise multiple regression using the SPSS 18.0 program. Results: The distribution of the subjects across the stages was: pre-contemplation, 17.7%; contemplation, 58.7%; preparation, 19.0%; action, 2.8%; maintenance, 1.8%. Analysis of variance showed that cognitive process (F=17.26, p<0.01), behavioral process (F=27.05, p<0.01), the pros of decisional-balance (F=7.07, p<0.01), the cons of decision-balance (F=5.82, p<0.01), and self efficacy (F=17.79, p<0.01) were significantly associated with the change of exercise behavior stages. The related factors of change affecting the change of exercise behavior stage were the cons of decision-making, counter conditioning, self re-evaluation, and body mass index, including 28.4% R-square. Conclusion: The transtheoretical model would be applicable to explain the exercise behavior of some women in nursing college. So, this study will be useful information for developing effective exercise behavior programs considering female students' stages of change.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.50-56
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• 2012

Vent mixer can provide main flow directly into a recirculation region downstream of the mixer to enhance fuel-air mixing efficiency. Based on experimental results of three-dimensional velocity, vorticity and turbulent kinetic energy obtained by a stereoscopic PIV method, the performance of the vent mixer was compared with that of the step mixer which was used as a basic model. Thick shear layers of the vent mixer induced the increase of the penetration height. The turbulent kinetic energy mainly distributed along a boundary layer between the main flow and the jet plume. This turbulent field activates mass transfer in a mixing region, leading to the mixing enhancement.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.6
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• pp.143-148
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• 2007

In the context of mass traffic, firewall system cannot record normal log files against DDoS attack. The loss of log record causes that a firewall system does not know whether a packet is normally filtered or not, and firewall log, which is an essential data for the counter measure of violation accident, cannot be verified as trusted. As a network speed increases, these problems happen more frequently and largely. Accordingly, the method to use simply additional hardware devices is not recommended for the popularization of firewall. This paper is devoted to verify the loss of iptable log that is the mother's womb of most domestic firewall systems and show that the log handling methods for conventional firewall systems are needed to improve.