• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.185-193
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• 2005

The present study composed a diesel-atkinson cycle of high expansion as a method of achieving high efficiency in diesel cycle engines. It also interpreted the cycle engine thermodynamically analysis to determine the possibility of the improvement of thermal efficiency and clarified the characteristics of several factors . According to the result of theoretical analysis, heat efficiency was highest when expansion-compression ratio Reど:1. In addition. diesel engines with high apparent compression ratio had higher expansion-compression ratio than otto engines and consequently their effect of high expansion was high. which in turn enhanced thermal efficiency. When the atkinson cycle was implemented in a real diesel engine by applying the miller cycle through the variation of the closing time of the intake valve, the effective compression ratio and the quantify of intake air decreased and as a result, the effect of high expansion was not observed. Accordingly. the atkinson cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case. heat efficiency increased by $4.1\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle. heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged Pressure equipment. Then a diesel-atkinson cycle engine is realized.

• Fire Science and Engineering
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• v.32 no.3
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• pp.95-107
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• 2018

This study analyzed the working conditions of the fire protection system in the Goyang Bus Terminal fire based on the fire investigation results. The results were as follows. First, extinguishing using an indoor fire hydrant was not attempted immediately after the fire burned the ceiling urethane foam. Second, a sprinkler alarm valve was turn off and did not work in the repair work space of the 1st basement. On the other hand, the sprinklers in the $2^{nd}$ basement, $1^{st}$ floor, $2^{nd}$ floor, and $3^{rd}$ floor worked and prevented the fire from moving to stories other than the $1^{st}$ basement. Third, although an exit light worked normally, it was not installed in the exit from the waiting room in the $2^{nd}$ floor to the bus stop. This resulted in many casualties. Fourth, although a fire receiver sent an electrical signal to the fan controller of the smoke control system, it was treated manually in the fan controller and the fan in the $2^{nd}$ floor did not work.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.127-135
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• 2016

Even thought modernized marine navigation devices help navigators, marine accidents has been often occurred and ship collision is one of the main types of the accidents. Various studies on the assessment method of collision risk have been reported, and studies using fuzzy theory are remarkable for the reason that reflect linguistic and ambiguous criteria for real situations. In these studies, collision risks were assessed on the assumption that the current state of navigation ship would be maintained. However, navigators ignore or turn off frequent alarms caused by the devices predicting collision risk, because they think that they can avoid the collisions in the most of situations. This paper proposes a model of predicting ship collision risk considering the general patterns of collision avoidance, and the approach is based on fuzzy inference and discrete event system specification (DEVS) formalism.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.95-97
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• 2018

The power quality of Single Phase Grid-Connected Inverters (GCIs) has received much attention with the increasing number of Distributed Generation (DG) systems. However, the performance of single phase GCIs get degraded due to several factors such as the grid voltage harmonics, the dead time effect, and the turn ON/OFF of the switches, which causes the harmonics at the output of GCIs. Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. To meet the harmonic standards a certain kind of harmonic controller needs to be added to the current control loop to effectively mitigate the low order harmonics. In this paper, the harmonic compensation is performed using a novel robust harmonic compensation method based on Digital Lock-in Amplifier (DLA). In the proposed technique, DLAs are used to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in the feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity, and implementation. The validity of the proposed harmonic compensation techniques for the single phase GCIs is verified through the experimental results with a 5kW single phase GCI. Index Terms -Single Phase Grid Connected Inverter (SPGCI), Harmonic Compensation Method, Total Harmonic Distortion (THD) and Harmonic Standard.

• English & American cultural studies
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• v.10 no.2
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• pp.231-266
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• 2010

This paper explores hybridity and hybridized relations that see mixings and crossings as the first moment of multicultural society. References to hybridity often assume that the definition and orientation of the term are located within biology; that is, hybridity constitutes a mixing of two formally discrete objects. In this regard, there seems to be a dialectical preoccupation with purity that goes hand in hand with discussions of hybridity. This dialectical reference to hybridity privileges whole, complete entities as the original instance before mixing, and in this way purity becomes reified. My analysis of hybridity foregrounds mixings that occur at the level of the social, not exclusively at the level of the biological. Hybridity contexts the myth of monoculturalism in the United States and foregrounds multiculturalism as the initial context around which difference has begun to be conceived. In destabilizing the myth of racial origins, this paper attempts to establish a retroactive construction of purity, which is historically, ideologically, and ethnically examined in Gloria Anzaldua's Borderlands/ La Frontera: The New Mestiza. Through this work composed of disparate narratives discourses, Anzaldua employs physical differences to ward off the colonial desire that has defined others as objects which are to be controlled. In this regard, this paper pursues the way that physical differences could be repositioned in terms of 'hybridity' that has been related to the cultural, historical, economical significations of borderlands. The space of borderlands is also a place marked psychologically; it will turn differences mobilized in the borderland into an acute consciousness that makes us recognize 'otherness' within ourselves. In sum, this paper attempts to elaborate the productive and creative interactions among disparate languages, classes, genders, and ideas, which will draw attention to their own interlocking nature.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.79-91
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• 2023

In response to the recent surge in aviation demand, major airports and aviation authorities continue to make efforts to formulate arrival and approach procedures that take into account efficient aircraft separation, noise and environmental issues of carbon (CO2) emissions. In order to ensure efficient traffic control and environmental issues, as a result, a new concept Trombone, Point Merge, etc. have been introduced and widely used in the domestic airspace. However, these new concept procedures which do not properly reflect the characteristics of the aircraft operation performance and the FMS vertical descent guidance hinder flight efficiency as well as bring in turn negative factors such as level-off flight and the use of drag device at the busiest phase of the flight descent operation, like the Continuous Descent Operation (CDO). Accordingly, throughout modification the current Standard Terminal Arrival Route (STAR) and Instrument Approach Procedure(IAP) that reflect the aircraft descent performance and the FMS guidance, the flight operation safety and efficiency is expected to be improved eventually. We herewith analyze and propose the way of improving flight efficiency in the arrival operation procedure by supplementary modification which consequently contribute to the aviation industry international competitiveness.

• The Korean Journal of Emergency Medical Services
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• v.13 no.3
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• pp.41-58
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• 2009

Objective : The purpose of this study is to identify actual operations and issues of wireless paging system operation for the aged living alone as the end users of wireless paging system primarily in Gwangyang city, and thereby to explore possible advanced and integrated ways to promote social safety network for the aged. Methods : The survey tool used in this study was a structured questionnaire form consisting of question items. The researcher hereof conducted this survey by means of direct visit and interview during two seasons, i.e. from February to August, 2008 and from December 2008 to March 2009, respectively. Results : 1) For general demographic characteristics, it was found that 90.9% of all respondents were women and 61.2% of all respondents were at age 75 to 84. for health conditions, it was found that more than 90% of all respondents often took medicines due to their unhealthy body, and most of respondents suffered from musculoskeletal diseases 79.3% and circulatory diseases 61.6%. for walking capacity, it was found that 45.5% of all respondents used walking aids, and disable respondents (11.5% of all respondents) were represented primarily by those with physical disability (52.6% of disable respondents). for actual use of medical institutions, it was found 47.3% of all respondents relied on local clinics, since they preferred neighborhood hospitals or clinics they can trust for medical care. for social activities and supports, it was found that 43.6% respondents had 'needs for assistance at times' and 33.9% respondents have 'no need for assistance'. And it was found that the major difficulties in living alone at old age were represented primarily by health problems 37.8% and economic difficulties 33.5%. 2) For characteristics related to wireless paging system, it was found that 90.3% respondents used wireless paging system recommended by firemen, and 28.5% respondents used this system. and it was found that 59.6% respondents used this system once, and 85.2% respondents used it because of acute or chronic diseases. more than 90% respondents thought that they knew about wireless paging system and considered themselves safe, but 83.6% respondents didn't attach a remote control on their upper clothes, and even 49.1% respondents turned off the power of wireless paging system due to their concern about electricity bill and noise. 3) It was found that 83.6% respondents felt it necessary to use wireless paging system, and wireless paging users felt more satisfied with using the system than non-users, and 50.7% showed high satisfaction at certain psychological benefits like 'confidence in coping with critical situations' and 'a sense of relief'. In addition, it was found that some respondents who answered that 'they didn't turn off the paging system as they knew how it works' and those who answered that they knew 'how to use it' showed relatively high satisfaction. And some respondents who kept it well and felt it necessary also showed high satisfaction. 4) It was found that the level of satisfaction our respondents felt with using wireless paging system varied significantly availability($x^{2}$ = 12.759, p = .002), psychological advantages($x^{2}$ = 12.174, p = .002), knowledge about how to use system($x^{2}$ = 7.021, p = .016), power on/off($x^{2}$ = 13.221, p = .001), level of knowledge about system($x^{2}$ = 21.002, p = .000), maintenance($x^{2}$ = 9.871, p = .007) and level of necessity($x^{2}$ = 34.939, p = .000) on the statistical basis.

• Journal of Life Science
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• v.7 no.4
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• pp.392-401
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• 1997

The poliovirus is a small, and non-enveloped virus. The RNA genome of poliovirus is continuous, linear, and has a single open reading frame. This polyprotein precursor is cleaved proteolytically to yield mature products. Most of the cleavages occur by viral protease. The mature proteins derived from the P1 polyprotein precursor are the structural components of the viral capsid. The initial cleavage by 2A protease is indirectly involved in the cleavage of a cellular protein p220, a subunit of the eukaryotic translation initiation factor 4F. This cleavage leads to the shut-off of cap-dependent host cell translation, and allows poliovirus to utilize the host cell machinery exclusively for translation its own RNA, which is initiated by internal ribosome entry via a cap-independent mechanism. The functional role of the 2B, 2C and 2BC proteins are not much known. 2B, 2C, 2BC and 3CD proteins are involved in the replication complex of virus induced vesicles. All newly synthesized viral RNAs are linked with VPg. VPg is a 22 amino acid polypeptide which is derived from 3AB. The 3C and 3CD are protease and process most of the cleavage sites of the polyprotein precursor. The 3C protein is also involved in inhibition of RNA polymerase II and III mediated transcription by converting host transcription factor to an inactive form. The 3D is the RNA dependent RNA polymerase. It is known that poliovirus replication follows the general pattern of positive strand RNA virus. Plus strand RNA is transcribed into complementary minus strand RNA that, in turn, is transcribed for the synthesis of plus strand RNA is transcribed into complementary minus strand RNA that, in turn, is transcribed for the synthesis of plus strand RNA strands. Poliovirus RNA synthesis occurs in a membranous environment but how the template RNA and proteins required for RNA replication assemble in the membrane is not much known. The RNA requirements for the encapsidation of the poliovirus genome (packaging signal) are totally unknown. The poliovirus infection cycle lasts approximately 6 hours.

• Asia pacific journal of information systems
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• v.18 no.3
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• pp.45-65
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• 2008

The rapid growth of the Internet has increased the amount of transmission of personally identifiable information. At the same time, with new Internet related technologies, organizations are trying to collect and access more personal information than before, which in turn makes individuals concern more about their information privacy. For their successful businesses, organizations have tried to alleviate these concerns in two ways: (1) by offering privacy policies that promise certain level of privacy protection; (2) by offering benefits such as financial gains or convenience. In this paper, we interpret these actions in the context of the information processing theory of motivation. This paper follows Hann et al.(2007)'s methods to analyze Internet users privacy concerns in Korea and tries to compare the findings. Our research objectives are as follows: First, we analyze privacy concern mitigation strategies in the framework of the expectancy theory of motivation. Subsequently, we show how the expectancy theory based framework is linked o the conjoint analysis. We empirically validate the predictions that the means to mitigate privacy concerns are associated with positive valences resulting in an increase in motivational score. In order to accommodate real-life contexts, we investigate these means in trade-off situation, where an organization may only be able to offer partially complete privacy protection and/or promotions and/or convenience, While privacy protection (secondary use, improper access) are associated with positive valences, we also find that financial gains can significantly increase the individuals' motivational score of a website in Korea. One important implication of this empirical analysis is that organizations may possess means to actively manage the privacy concerns of Internet users. Our findings show that privacy policies are valued by users in Korea just as in the US or Singapore. Hence, organizations can capitalize on this, by stating their privacy policy more prominently. Also organizations would better think of strategies or means that may increase online users' willingness to provide personal information. Since financial incentives also significantly increase the individuals' motivational score of website participation, we can quantify the value of website privacy protection in terms of monetary gains. We find that Korean Internet users value the total privacy protection (protection against errors, improper access, and secondary use of personal information) as worthy as KW 25,550, which is about US 28. Having done this conjoint analysis, we next adopt cluster analysis methodology. We identify two distinct segments of Korea's internet users-privacy guardians and information sellers, and convenience seekers. The immediate implication of our study is that firms with online presence must differentiate their services to serve these distinct segments to best meet the needs of segments with differing trade-offs between money and privacy concerns. Information sellers are distinguished from privacy guardians by prior experience of information provision, To the extent that businesses cannot observe an individual's prior experience, they must use indirect methods to induce segmentation by self-selection as suggested in classic economics literature of price discrimination, Businesses could use monetary rewards to attract information sellers to provide personal information. One step forward from the societal trends that emphasize the need of legal protection of information privacy, our study wants to encourage organizations and related authorities to have the viewpoints to consider both importance of privacy protection and the necessity of information trade for the growth of e-commerce.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.21-28
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• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.