• 대한인간공학회지
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• 제26권3호
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• pp.117-124
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• 2007

A few people are frequently using Korean text entry function in the mobile phone. To make matters worse, too many kinds of Korean text entry methods exist in the market, compelling mobile phone users to learn how to input texts all over again, whenever they purchase a new mobile phone. The purpose of this study is to propose a universal design of Korean text entry method for mobile phones. Several experiments and several questionnaire surveys were conducted in order to induce design factors for the universal design. Participants were mobile phone users with the diverse levels of text entry expertise and with the diverse ages. The results of this investigation were identical, irrespective of participants' age and expertise. The efficiency of the text entry method was not more important factor than memorability. The layout of vowels to keypad was preferred to map just 3 strokes to the 3 buttons so that users can make for themselves vowels that they want to input. The preference on the consonants layout was different according to investigation methods. According to the survey, it was preferred that consonants were arranged by alphabet order. However, the result of text entry speed measurement was that the arrangement by alphabet order was not superior to the typical arrangement. Such results may be used to design mobile phones for diverse users.

• 한국정밀공학회지
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• 제17권6호
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• pp.111-118
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• 2000

The design of reference trajectory with respect to drag acceleration is necessary to decelerate from hypersonic speed safely after atmosphere re-entry of space vehicle. The re-entry guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of 6 trajectory constraints during the re-entry flight. This reference drag acceleration profile can be considered as the reference trajectory. The cost function is composed of the accumulated total heating on vehicle due to the reduction of weight. And a regularization is needed to prevent optimal drag profile from varying too fast and achieve realized trajectory. This paper shows the relations between velocity, drag acceleration and altitude in drag acceleration profile, and how to determine the reference trajectory.

• 한국철도학회논문집
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• 제15권1호
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• pp.37-41
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• 2012

경부고속철도는 운영환경(차량,구배,곡선,시설물 등)에 따라 궤도회로를 여러 개의폐색으로 분할하여 운행하는 고정폐색방식의 열차제어시스템으로 운행된다. 고정폐색방식 열차제어시스템은 선행열차의 점유폐색을 기준으로 진입/진출폐색속도, 목표거리, 감속도와 같은 운행정보를 차상열차제어장치로 전송하여 연속적으로 열차를 제어하는 방식으로, 경부고속철도 열차제어시스템은 열차가 해당 폐색의 진입/진출속도를 초과할 경우, 비상제동명령을 내려 열차의 안전한 운행을 보장한다. 본 논문에서는 안전한 운행을 위해 폐색에 할당되는 속도제어코드의 생성원리를 분석하여, 최고운행속도와 운행차량특성에 따른 속도제어코드를 도출하고, 도출된 속도제어코드에 따른 운행시격 분석을 통해 열차 운행효율을 분석하였다. 이와 같은 연구는 기존 고속철도의 증속 및 신규 고속철도 열차제어시스템 설계 자료로 활용될 수 있다.

• Carbon letters
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• 제19권
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• pp.89-98
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• 2016

Taguchi’s experimental design was employed in the melt spinning of molten mesophase pitch to produce carbon fibers. The textures of the obtained carbon fibers were radial with varied crack angles, as observed by scanning electron microscopy and polarized optical imaging. The diameter, crack angle, preferred orientation, and tensile modulus of the produced samples were examined to investigate the influence of four spinning variables. The relative importance of the variables has been emphasized for each characteristic. The results show that thicker carbon fiber can be obtained with a smaller entry angle, a higher spinning temperature, a reduced winding speed, and an increased extrusion pressure. The winding speed was found to be the most significant factor in relation to the fiber diameter. While it was observed that thicker carbon fiber generally shows improved preferred orientation, the most important variable affecting the preferred orientation was found to be the entry angle. As the entry angle decreased from 120° to 60°, the shear flow was enhanced to induce more ordered radial alignment of crystallite planes so as to obtain carbon fibers with a higher degree of preferred orientation. As a consequence, the crack angle was increased, and the tensile modulus was improved.

• 대한기계학회논문집B
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• 제23권1호
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• pp.58-68
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• 1999

The entry compression wave, which forms at the entrance of a high-speed railway tunnel, is closely related to the pressure transients in the train/tunnel systems as well as an impulsive noise appearing at the exit of the tunnel. In order to alleviate such undesirable phenomena, some control strategies have been applied to the compression wave propagating inside the tunnel. The objective of the current work is to investigate the effect of tunnel entrance hoods on the entry compression wave at the vicinity of the tunnel entrance. Three types of entrance hoods were tested by the numerical method using the characteristics of method for a wide range of train speeds. The results show that the maximum pressure gradient of compression wave can be considerably reduced by the tunnel entrance hood. Optimum hood shape necessary to reduce the pressure transients and impulsive noise was found to be of an abrupt type hood with its cross-sectional area 2.5 times the tunnel area. It is believed that the current results are highly useful in predicting the effects of entrance hoods and in choosing the shape of proper hood.

• Journal of Information Processing Systems
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• 제14권1호
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• pp.228-238
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• 2018

With the rapid advancement of Internet services, there has been a dramatic increase in services that dynamically provide Internet resources on demand, such as cloud computing. In a cloud computing service, because the number of users in the cloud is changing dynamically, it is more efficient to utilize a flexible network technology such as software-defined networking (SDN). However, to efficiently support the SDN-based cloud computing service with limited resources, it is important to effectively manage the flow table at the SDN switch. Therefore, in this paper, a new flow management scheme is proposed that is able to, through efficient management, speed up the flow-entry search speed and simultaneously maximize the number of flow entries. The proposed scheme maximizes the capacity of the flow table by efficiently storing flow entry information while quickly executing the operation of flow-entry search by employing a hash index. In this paper, the proposed scheme is implemented by modifying the actual software SDN switch and then, its performance is analyzed. The results of the analysis show that the proposed scheme, by managing the flow tables efficiently, can support more flow entries.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권10호
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• pp.1770-1782
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• 2011

A brain-computer interface (BCI) is a communication system that translates brain activity into commands for computers or other devices. In other words, BCIs create a new communication channel between the brain and an output device by bypassing conventional motor output pathways consisting of nerves and muscles. This is particularly useful for facilitating communication for people suffering from paralysis. Due to the low bit rate, it takes much more time to translate brain activity into commands. Especially it takes much time to input characters by using BCI-based typewriters. In this paper, we propose a brain-operated typewriter which is accelerated by a language prediction model. The proposed system uses three kinds of strategies to improve the entry speed: word completion, next-syllable prediction, and next word prediction. We found that the entry speed of BCI-based typewriter improved about twice as much through our demonstration which utilized the language prediction model.

• 한국도로학회논문집
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• 제14권3호
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• pp.173-182
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• 2012

휴게소 진 출입부는 설계속도 등이 급변하는 구간으로 교통안전 취약구간이며 특히, 휴게소 진입부는 감속과 주차공간 검색 두 가지 작업이 동시에 수행되므로 이용차량의 안전성을 확보할 수 있는 설계기준이 필요하다. 국내의 경우 영업소나 나들목, 분기점 같은 출입시설에 대한 기하구조 기준은 수립되어 있는 반면, 도로의 부속시설인 휴게소에 대한 상세한 기하구조 기준은 없는 실정이다. 이에 본 연구에서는 일반형 휴게소 135개소를 대상으로 한 현장조사 및 사고조사 자료를 활용하여 휴게소진 출입부 기하구조에 대한 문제점을 도출하였다. 휴게소 진 출입부의 설계구간을 분류하고 각 구간에 대한 설계요소를 도출한 후, 휴게소 진 출입부를 대상으로 속도조사 및 차량주행행태 조사를 수행하고 분석을 통해 설계요소별 최소 기준을 도출하였다. 진입 연결로의 시/종점 속도에 따라 감속거리 산정식을 이용하여 진입 연결로의 최소길이는 40m를 제안하였고, 주행행태를 기반으로 선형 안전성 평가를 통해 접속 설치각은 12~$17^{\circ}$를 제안하였다. 개발된 휴게소 진입부 설계기준은 신설되는 휴게소 뿐만 아니라 기존 휴게소에 대해 현실적으로 적용 가능한 개선방안을 제시할 수 있을 것으로 판단된다.

• 무역학회지
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• 제48권4호
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• pp.1-21
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• 2023

본 연구는 우리나라 해외진출 중소기업을 대상으로 국제화 속도와 국제화 범위가 성과에 미치는 영향을 규명한다. 실증분석을 통해 해외시장에 최초 진출하는 시간관점의 국제화 속도와 해외시장 진출 이후 지리적 관점의 국제화 범위는 모두 국제화 성과에 유의한 정(+)의 영향을 미치는 것으로 확인되었다. 이는 해외시장에 빠르게 진출할수록, 해외진출 국가의 범위가 넓어질수록 성과에 긍정적인 영향이 있음을 의미한다. 또한 국제화 범위가 국제화 속도보다 국제화 성과에 유의하게 더 큰 영향을 미치는 것으로 분석되었다. 해외시장 최초 진출 속도도 중요하지만 진출이후 해외진출 국가의 지리적 범위의 단계적인 확대가 성과에 의미가 있음을 시사한다. 또한, 경영자의 해외시장에서 비즈니스 경험의 특성은 국제화 범위와 국제화 성과의 관계를 강화시키는 조절효과가 확인되었다. 결론적으로 자원과 역량이 상대적으로 부족한 중소기업의 국제화 과정에서 경영자의 글로벌지향성과 함께 해외시장으로의 빠른 진출 속도와 함께 진출이후의 범위의 균형적인 관리가 필요함을 의미한다.

• International Journal of Aeronautical and Space Sciences
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• 제12권3호
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• pp.211-224
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• 2011

This is a written version of an hour-long lecture delivered by the author on June 30, 2011, as Plasmadynamics and Lasers Award Lecture at the AIAA 2011 summer conference in Honolulu, Hawaii. The author proposes that two areas of planetary entry physics be pursued in the future: outer planet aero-capturing and study of aerodynamics of meteoroid entries, both for the purpose of advancing the understanding of the possible extraterrestrial seeding of building blocks of life. For outer planet aero-capturing, the author proposes to develop new shock tube facilities that will produce up to 30 km/s of shock speed without causing photo-ionization of the driven gas by the radiation from the hot driver gas. Regarding meteors, the author proposes to carry out laboratory testing of the Tunguska event and of the seeding of amino acid molecules using a ballistic range which shoots a snowball laden with amino acid molecules toward a water surface.