• Journal of Korean Neurosurgical Society
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• 제63권1호
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• pp.14-25
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• 2020

Proximal flow control achieved with a balloon guide catheter (BGC) during endovascular treatment of acute ischemic stroke is reviewed in this article. In clinical practice, BGCs offer a multi-faceted approach for clot retrieval by creating proximal flow arrest, reducing embolic burden, and shortening procedure time. Evaluation of frontline thrombectomy procedures with BGCs revealed advantages of combined use over the conventional guide catheter (CGC), notably in the significant reduction of distal emboli to both the affected and previously unaffected territories. Recently, new measures of early and complete reperfusion at first thrombectomy pass have been identified as independent predictors of improved outcomes, which were consistently demonstrated with use of BGC as a safe and effective option to minimize number of passes during intervention. Prior randomized controlled trials reported the positive correlation between BGC-treated patients and a lower risk of mortality as well as shortened procedure time. While BGC use is more common in stent retriever-mediated mechanical thrombectomy, preliminary data has shown the potential benefit of device application during contact aspiration thrombectomy to achieve successful recanalization. However, the question of which major endovascular strategy reigns superior as a frontline remains to be answered. Along with clinical case assessments, BGC performance during in-vitro simulation was analyzed to further understand mechanisms for optimization of thrombectomy technique.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.1977-1980
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• 2014

Background: The popularity of the narghile waterpipe, also referred to as hookah, shisha or hubble-bubble has increased tremendously during the past few decades. The aim of this study was to expose perception of narghile among a representative sample of university students in Sakarya University campus. Materials and Methods: Written approval was taken from the local education authority. An anonymous questionnaire which was prepared by the investigators and contained 17 questions was administered. Nine of the questions were related to socio-demographic characteristics and eight were related to the students harm perceptions about waterpipe. A total of 1,320 questionnaries were received and after preliminary evaluation 1,255 (95.7%) were found to be suitable for evaluation. The data was evaluated in SPSS program by using percentages and averages. Results: The $mean{\pm}SD$ age of the students was $20.8{\pm}2.29$ years (min 18, max 32). There were 864 (68.8%) females and 391 (31.2%) males. A total of 6.3 % of the students (n=79) believed that waterpipe is not harmful because its smoke does not burn the lungs. Almost one-third (n=318) think that the carcinogenic chemicals are filtered while waterpipe smoke passes from the water; 12.1 % of the students (n=152) checked "true" for the statement of "waterpipe smoke contains no nicotine". It is seen that 14.0 % of the students (n=176) think waterpipe with fruit/aroma is healthier than plain waterpipe. Conclusions: As a result of this study, it is found out that a substantial number of university students have false beliefs on harmful effects of waterpipe smoking.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.693-696
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• 2008

4세대 이동 통신 서비스를 위한 시스템들은 멀티미디어 서비스를 지원하기 위해 대용량 데이터 전송이 가능한 OFDM(Orthogonal frequency Division Multiplexing) 방식을 이용하고, 서비스의 질을 높이기 위해 통신 영역을 세분화하여 Macro Cell, Pico Cell, Femto Cell 등으로 구성하고 있다. 통신 영역의 세분화로 인해 기존에 단일 Cell 을 사용하는 것과 달리 동일한 채널에서 Cell을 중첩시켜 서비스해야 하므로 시스템들 간의 대역간 간섭이 문제가 된다. 특히, OFDM 신호는 독립적으로 변조된 많은 부반송파들로 구성되므로 이들이 동위상으로 더해질 때 신호의 진폭이 증가하여 PAPR (Peak-to-Average Power Ratio) 문제가 발생한다. 높아진 PAPR은 전력 증폭기와 같은 비선형 소자를 통과하면서 신호의 왜곡이 발생하여 대역 외 스펙트럼 방출이 발생하므로 대역간 간섭으로 작용한다. 본 논문에서는 대역간 간섭을 최소화하기 위해 PAPR 감소기법을 적용한 후 전력증폭기와 같은 비선형 소자를 통과하면서 발생하는 대역 외 스펙트럼 방출에 대하여 분석하였다.

• 한국안전학회지
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• 제21권2호
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• pp.70-79
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• 2006

many plumbing system are needed in the ceiling of the building as it becomes advanced more and more. This leads to make effective space between ceiling level and slab less. Also, piping system is not suitably arranged and operated if it is bent around the columns which they are a lot. But this system can be more effective if it passes through the columns directly. Most people think that those columns should not be damaged with such as holes. But actually this is existed in a hotel building in switzerland. This study is to fing out how much capacity the columns become damaged and low using model size of $20cm{\times}30cm$ rectangular section, and 160cm long, in the structural test. it's compressive strength is focused on $240kg/cm^{2}$ design strength, commonly used in korea. Compressive test for them was done at Hanyang University using UTM one thousand tone(1000t) capacity. Variable numbers for the study are one hole of dia 3cm with distance 20cm or 40cm, two holes of dia 3cm with 20cm and 40cm distance, one hole of dia 5cm with distance 20cm and 40cm, two holes of dia 5cm with 20cm and 40cm distance, me eccentric hole with 20cm and 40cm distance, Normal(without hole). two test specimens of each variable are made for the test. ED5H20 capacity was 16.7% decreased, compared to normal one. While ED5H40 distant 40cm from the end of column top showed 19.5% capacity decrease, compared to normal one. Strain of ED5H20 diameter 5cm, in distance of 20cm form the top of the column was less 5% than the one of diameter 3cm. Finally, conclusions are that in case of hole diameter 3cm, located at 20cm from the end of the column top, capacity was decreased down to 3, percent only compared to the same diameter hole with 20cm distant from the end of it.

• 영어영문학
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• 제58권6호
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• pp.1143-1165
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• 2012

Tinted with ontological concern, Ted Hughes passes through an existential climate, eventually confirms death( or nothingness) as the new foundation of his poetry, and explores the various paradoxical effects of nothingness. Nihilism, fraught with rather negative and traumatic themes such as death, melancholy, and despair can, however, generate being (even in multiple modes), animalistic vitality, and insubstantial specters. Among these new functions of nothingness animality and spectrality are the most notable in Hughes's poetry. A considerable number of animals and bioorganisms that Hughes introduces exhibit the enormous energy derived from the dignity of death, from subversive challenges against the established hierarchy, and from new and dynamic multifaceted sources of nothingness. In other words, Hughes's animals, yield surplus power beyond themselves, as if they are demi-gods; in short, they feature the sublime as unidentified terrifying effects of nothingness. In a sense, animality means allowing some level of violence without legal sanction. Hughes inaugurates this kind of all bigotry-eradicating violence and attempts to subvert higher beings such as humans and gods, and existing doctrines: thrushes rise up against the animal and human worlds; a rush of ghostly crabs at night press through the human world. Hughes also resists the highest being, God, employing the technique of rewriting God's theology. Dirty, anomalous crows attack, subvert, and dismember the delicate, indurate, and thorough system of logos. Hughes, of course, does not place the animals merely in lofty regard, aware of the ulterior deprivation of the sublime animality, the trace of existential negativity. Thus, a seemingly omnipotent crow can become a mere beggar guzzling ice cream from the garbage bin on the beach. In addition, the violent and dignified aspects of nothingness can be transformed to reveal the thin and trivial traits as unreliable specters. Dark, heavy, and terrible nullity lessens its own volume and mass, and exposes the airy waves of shadows or specters. However, owing to nullity's untraceable track, the scarcity and unfamiliarity of the phantoms inversely display their foreign gigantic effects such as fantasy and violence.

• 한국농공학회논문집
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• 제51권5호
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• pp.19-24
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• 2009

This study was conducted to provide fundamental data for design of air inflating apparatus of air-inflated double-layer plastic greenhouse. The variation of static pressure in air tube for different fans and filters, filtering performance for various kinds of filters and destruction phase of experimental greenhouse collapsed by excessive static pressure in air space were analyzed. The general type of forward centrifugal fan was recommended for inflating air space in air-inflated double-layer plastic greenhouse. The experimental greenhouse was collapsed down by excessive static pressure just like fallen by heavy snow load acting on it. The static pressure in air tube without filter decreased linearly as the number of outlet openings increased. But the pressure in air tube with filter declined quadratically, the decremental ratio diminished by the increase of outlet openings. The higher filtering efficiency and the greater decrements of static pressure in air tube, the larger capacity fan was required for maintaining proper static pressure in air space. Because the porosities of filter were blocked by dust as time goes by, the static pressure in air tube with filter decreased. The higher filtering efficiency, the less decremental ratio of static pressure in air tube as time passes by. Considering the filtering efficiency, decrement of static pressure and thickness of filter, the 5mm thickness filter of 75% efficiency was recommended for air inflating filter of air-inflated double-layer plastic greenhouse.

• 소성∙가공
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• 제27권4호
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• pp.250-256
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• 2018

Oxygen-free copper (OFC) was prepared as a 90 mm cube and then processed with Multi-Axial Diagonal Forging - Initialization of Prior manufacturing History (MADF). The MADF process has been newly developed as a severe plastic deformation method. The MADF process consists of upset forging with a thickness reduction of 30% and diagonal forging with a diagonal angle of $135^{\circ}$. 1 cycle process consists of a 12 passes forging process. In order to analyze the characteristic changes according to the number of iterations, 1, 2, and 3 cycles of the MADF process were performed. The OFC specimens were MADF processed without surface cracks up to 3 cycles. The microstructure, hardness and tensile test of processed materials were analyzed to study the change of material properties according to the amount of MADF process. The results showed that the MADF process effectively refined the microstructure and increased the strength of OFC. In the case of specimens processed for more than 2 cycles, the grains of all measurement regions were refined to be less than $7{\mu}m$ of grain size. The 1 cycle MADF processed OFC showed the highest mechanical properties with the hardness of 132 HV and tensile strength of 395 MPa. Hardness and strength seemed to be saturated when processed over 2 cycles.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.274-277
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• 2008

Rekeying is the process of changing the encryption key of an ongoing communication. The main objective is to limit the amount of data encrypted with the same key. The IEEE 802.11 standard defines the Wired Equivalent Privacy, or WEP, encapsulation of 802.11 data frames. MAC at sender encrypts the payload (frame body and CRC) of each 802.11 frame before transmission using RC4 stream cipher. MAC at receiver decrypts and passes data to higher level protocol. WEP uses symmetric key stream cipher (RC4) where same key will be used for data encryption and decryption at the sender and the receiver. WEP is not promising with the advancement of the wireless technology existing today. We propose to use the existing information to define the security attributes. This will eliminate the steps that regenerated keys have to be sent to each other over certain period. The rekeying scheme is according to the number of bytes transmitted. Therefore, even the attacker has recorded the packets, it will be insufficient information and time for the attacker to launch the attacks as the key is not deterministic. We develop a packet simulation software for packet transmission and simulate our propose scheme. From the simulation, our propose scheme will overcome the weak WEP key attack and provide an alternative solution to wireless packet transmission. Besides that, our solution appears to be a software approach where only driver updates are needed for the wireless client and server.

• Journal of Information Science Theory and Practice
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• 제6권1호
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• pp.65-82
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• 2018

Purpose - This research aims to examine collaboration from a disciplinary perspective in Korea. There are needs to explore to what extent researchers collaborate by discipline and across discipline along with the impact of collaboration. Design/methodology/approach - In order to investigate collaboration with respect to entire discipline areas and author-declared discipline information we analyzed a national researcher information database (Korean Researcher Information) with a citation index database (Korean Citation Index) covering the entire range of discipline. This study analyzed the data sets for 10 years (2004-2013) including a total of 8 categories and 119 sub-categories of disciplines, 109,551 researchers, 650,263 articles, and 1,170,039 citations in Korea. Findings - The results demonstrate that there are different intensities of collaboration from heavy to minimal across disciplines. In examining collaboration in terms of author and discipline levels, the results show that collaboration in author level rises, then inter-disciplinary collaboration increases accordingly, in most of the 119 discipline sub-categories. A number of disciplines, however, tended to collaborate more intensely within their own rather than with other disciplines. Moreover, the impact of collaboration tended to change over time depending on the types of collaboration. Specifically, inter-disciplinary collaboration was likely to have more immediate impact as pioneer research, especially among more than three disciplines, whereas the impact of intra-disciplinary collaboration is higher as time passes. Originality/value - In this research, a disciplinary investigation on collaboration is conducted for the entire range of disciplines in Korea. Through analyzing distinctive author-declared discipline information from the KRI, this research examines the intensities of collaboration across disciplines, collaboration in author level, and the impact of collaboration.

• 수산해양기술연구
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• 제46권4호
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• pp.430-440
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• 2010

To investigate the catches of jack mackerel fishery, a series of fishing experiments was conducted in the high seas of the southeastern Pacific Ocean ($30^{\circ}S-38^{\circ}S,\;82^{\circ}W-95^{\circ}W$) during the period of 9 August to 18 December, 2003 by commercial fishing vessel and research vessel. The number of 205 tows fishing was carried out in the southeastern Pacific Ocean. The total catch was 1,988 ton and CPUE was 2.4 ton/hour. CPUE showed high values in the frontal zone during the survey. Main target species caught from the experimental fishing were the jack mackerel, Trachurus murphyi (98.1%) and chub mackerel, Scomber japonicus (1.9%) as bycatch. Body length of the jack mackerel was different between female and male. The high mean catch per unit effort of jack mackerel was showed when the fishing ground of jack mackerel fishery was over the $110^{\circ}W$ in the southeastern Pacific Ocean. But the fluctuation of the catch per unit effort in the western part of fishing ground was not matched with those year. Reliable physical and oceanographical information will be useful for the efficiency of fishing activity. According to the result of monthly movement of center of fishing ground, the fishing activity of jack mackerel fishery was performed northward in the southeastern Pacific Ocean as time passes.