• 대한약침학회지
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• 제12권4호
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• pp.77-88
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• 2009

Objectives : The purpose of this study was to compare the effect of acpuncture and electro-acupuncture of low(EA(L)) and high(EA(H)) frequency at Haegye(ST41) on intestinal hypomotility induced with loperamide in rats. Methods : We made suppressed state of intestinal motility with loperamide in rats and carried out needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture at ST41 in rats devided into pre-treatment group and post-treatment group. We fed charcoal to them after the treatment and measured the travel rate of charcoal in the gastrointestinal track to analyze which treatment is more effective in state of intestinal hypomotility. Results : None of acupuncture, EA(L) and EA(H) at ST41 had significant influences on intestinal motility of rat in normal state. Needle retention at ST41 did not significantly increase intestinal motility suppressed with loperamide in rats. Pre-treatment of EA(L) and EA(H) at ST41 significantly increased intestinal motility suppressed with loperamide in rats. Post-treatment of EA(L) and EA(H) at ST41 did not have significant influences on intestinal motility of rat in normal state. Conclusions : These results suggest that treatment of EA(L) and EA(H) at ST41 may be effective on gastric disorders such as intestinal hypomotility and its effect had more prevention than cure. Further study is necessary to know more effects of ST41 and electro-acupuncture of low and high frequency.

• 대한교통학회지
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• 제27권6호
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• pp.147-156
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• 2009

본 논문에서는 기 운영되고 있는 도시부 대중교통을 대상으로 노선의 운행빈도 설계 문제의 모델링 및 해법 개발을 위한 방법론을 제시하였다. 개발된 운행빈도 모형은 이중구조 모형으로서 상위 운영자 모형은 이용 가능한 총 차량 대수제약과 최소/최대 운행빈도 제약 하에 비용과 수익을 모두 포함한 순비용을 최소화하는 비선형 최적화 모형이고, 하위 사용자 모형은 가변수요와 용량제약으로 인한 노선의 혼잡, 그리고 노선 간환승에 따른 지체를 고려한 확률적 사용자 평형수단/경로선택 모형이다. 모형의 해법으로는 상위 모형의 경우 목적함수의 그레디언트를 기반으로 하는 "그레디언트 투사 해법"을 제안하였고, 하위모형의 경우는 기존의 "반복조정해법"을 활용하였다. 또한, 구축된 모형과 해법을 소규모 예제네트워크에 적용하여 그 수렴성과 도출된 해를 분석하였다. 본 논문의 운행빈도 설계방법론은 노선의 운영 효율성을 진단 평가하고, 투입 차량대수 제약 하에 대중교통 운영 효율을 개선하는 방안을 마련하는 데 있어 이론적인 토대로 활용될 수 있을 것으로 기대된다.

• 한국항행학회논문지
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• 제2권2호
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• pp.143-156
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• 1998

인천국제공항이 동북아 허브 공항으로서 성공하려면 동 공항을 중심으로 한 비행편 구성이 경쟁 공항보다 효율적이어야 한다. 본 논문은 항공여행자의 비행편 선택 행위를 분석하여 인천국제공항 허브화 성공을 위한 비행편 구성 계획에 이용하는 방법을 연구했다. 규제가 완화된 시장에서는 소비자의 선호 파악에 기초한 사업 계획이 유효하므로 비집계형 선택모델에서 산출할 수 있는 여행시간가치, 운항빈도와 여행시간의 대체율 등을 이용하여 비행편 구성 계획을 할 필요가 있을 것이다.

• 수면정신생리
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• 제3권2호
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• pp.18-31
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• 1996

Jet-lag can be defined as the cumulative physiological and psychological effects of rapid air travel across multiple time zones. Many reports have suggested that age-related changes in sleep reflect fundamental changes in the circadian system and in significant declines in slow wave sleep. Jet lag is a dramatic situation in which the changes of the phase of circadian process and homeostatic process of sleep occur. Thus the authors evaluatead the changes of sleep-wake cycle from jet lag by age. Thirty-eight healthy travellers were studied for 3 days before and 7 days after jet-flights across seven to ten time zone. They were aged 19-70, They trareled eastbound, Seoul to North America (USA, Canada). Sleep onset time, wake-up time, sleep latency, awakening frequency on night sleep, awakening duration on night sleep, sleepiness at wake-up and nap length were evaluated. Our results suggest that by the 7 to 10 time zone shift, the old age group was significantly influenced in sleep-wake cycles. The date on which subjective physical condition was recovered was $6.23{\pm}83$ day after arrivals for old age group, while for young and middle age group, $4.46{\pm}1.50$ day and $4.83{\pm}1.52$ day, respectively. In old age group, sleep onset time was later than baselines and could not recover untill 7th day. But in other groups, the recovery was within 5th day. Nap dura fion was longer in old age group through jet lag than younger age group. In other parameters, there was no definite difference among three age groups. Our results suggested that the old age was significantly influenced by the disharmony between internal body clock and sleep-wake cycle needed at the travel site. Thus we proved that recovery ability from jet lag was age-dependent as well as travelling direction-dependent. To demonstrate more definite evidence, EEG monitoring and staging of sleep were funthun encouraged.

• 대한교통학회지
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• 제31권2호
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• pp.80-89
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• 2013

본 연구는 지역간 여객 철도의 노선계획을 최적화하는 방법에 관한 연구이다. 본 연구의 노선계획 모형은 다양한 차종이 운용되는 철도노선에서 이용자비용(이용자의 총 통행시간)과 운영자비용(열차 운행비용, 유지 보수비용, 차량 구입비용)의 합을 최소화하고자 하는 혼합정수계획 수리모형으로 구축되었고, 모형의 해법으로 분기한정법이 사용되었다. 수요의 변화, 열차 속도의 변화, 정차스케줄 수의 변화 등에 대한 민감도 분석 결과도 제시하였고, 국내 경부선의 사례연구를 통하여 각 열차차종의 차종별 수요 분할 뿐만 아니라 최적 정차스케줄과 운행빈도를 동시에 산출할 수 있음을 보여주었다. 본 연구의 모형과 결과는 열차 운영 전략을 수립하거나 새로운 철도 시스템의 효율성을 분석하거나 이용자 운영자의 사회적 비용을 산정하는 경우 등에 적용될 수 있다.

• Journal of Biosystems Engineering
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• 제13권2호
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• pp.38-45
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• 1988

This study was intended to develop the system automatically controlling travel direction of combine by means of sensing paddy rows. The control system was composed of three detecting levers having different length, micro-switch, microcomputer and electro-hydraulic control system. Sensor and control system developed was tested to estimate optimum design values and its actual performance as installed in combine. The computer simulation and performance test at simulated and actual field were conducted to test for possibility of practical use. The results of the study arc summarized. as follows: 1. The travel traces of combine hiving the conventional sensor with 2 levers and the new sensor detecting the slope of paddy rows were compared through computer simulation. Turning frequency of combine having new sensor was fewer than that of conventional sensor, but the rate of turning for the combine with new sensor was much greater than that of conventional sensor. 2. As sensor was established behind the tip of divider, the sensor itself well followed paddy rows but the tip of divider did not, resulting in divider being deviated from paddy rows. It was analyzed that the sensor should be attached closer to the tip of divider to have a better performance of the control system. 3. The greater the length of sensor lever for given location of sensor attachment and combine forward speed, the higher sensitivity of turning in control system. Moreover, increasing combine speed resulted in a worse performance of control system following paddy rows. Consequently, it was necessary that an optimum length of sensor attachment and for the range of combine operational speed. 4. Field test of combine installed with the sensor and electro-hydraulic system developed in this study showed that it may be operated smoothly and well behaved to paddy rows to 4th gear of combine speed which was 59cm/s. Consequently. it was concluded that the combine with the guidance control system developed in this study may be successfully used for paddy combining.

• 한국항만경제학회지
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• 제32권4호
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• pp.183-192
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• 2016

항공 및 해상교통수단의 발전과 소득 및 여가시간의 증대로 해외로 출국하는 여행객의 수는 매년 증가하고 있는 실정이다. 하지만 충청남도는 한국에서 유일하게 공항이 없는 지역으로 충남도민들은 해외 여행 시 인천 등 타 지역을 통해 여행을 하여야 하는 불편함을 겪고 있다. 이에 본 연구는 충남도민들의 접근교통에 따른 운송수단 선택행동에 관하여 분석하였다. 이를 위하여 Stated-preference(SP) data를 활용하여 Multinominal Logit Model(MNL)을 이용하였다. 충남도민들이 해외여행 시 운송수단 선택의 경우 거주지에 따라 다른 특성을 보이는 것으로 분석되었다. 또한 거주지-공항/항만까지 접근성이 공항/항만-목적지까지 운송보다 교통수단 선택행동에 더 큰 영향을 미치는 것으로 분석됐다. 특히 접근소요시간 및 접근교통 운영 빈도요인이 가장 큰 영향을 미치고 있는 반면 운송시간이 상대적으로 적은 영향을 미치고 있는 것으로 분석되었다. 운송수단의 선택은 여객터미널 선정에도 영향을 미치는 것으로 여객터미널 운영사는 접근성을 중요하게 고려하여야 한다. 접근교통수단의 개선은 인천공항을 이용하여 중국으로 출국하는 이용객 중 일부 여객 수요가 전환될 수 있다는 결론이 도출되었다.

• 한국철도학회논문집
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• 제19권5호
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• pp.656-662
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• 2016

본 연구에서는 휴대전화 이용자의 시간대별 기지국 위치정보를 기반으로 하여 이용자의 이동경로를 추적하고, 기/종점을 추출하여 OD를 구축하였다. OD 구축시 통행거리가 길어질수록 통신횟수가 많아짐을 고려하여 통행거리별 평균통신횟수를 산출/반영하였고, 가정기반 통행만을 대상으로 수도권 중심의 OD를 구축하였다. 셀 단위로 집계된 휴대전화 자료를 법정동 단위로 변환하고, 이를 행정동 단위로 변환하여 본 연구에서 구축한 OD를 KTDB OD와 비교분석 한 결과, 시/군/구 단위 OD와 동 단위 OD의 상관계수는 각각 0.98, 0.85로 나타나 상당한 연관성이 있는 것으로 분석되었다.

• Steel and Composite Structures
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• 제17권6호
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• pp.891-906
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• 2014

This study aims to present a three dimensional finite element model to investigate the wave propagation in a concrete filled steel tubular column (CFSC) due to transient impact load. Both the concrete and steel are regarded as linear elastic material. The impact load is simulated by a semi sinusoidal impulse. Besides the CFSC models, a concrete column (CC) model is established for comparing under the same loading condition. The propagation characteristics of the transient waves in CFSC are analyzed in detail. The results show that at the intial stage of the wave propagation, the velocity waves in CFSC are almost the same as those in CC before they arrive at the steel tube. When the waves reach the column side, the velocity responses of CFSC are different from those of CC and the difference is more and more obvious as the waves travel down along the column shaft. The travel distance of the wave front in CFSC is farther than that in CC at the same time. For different wave speeds in steel and concrete material, the wave front in CFSC presents an arch shape, the apex of which locates at the center of the column. Differently, the wave front in CC presents a plane surface. Three dimensional effects on top of CFSC are obvious, therefore, the peak value and arrival time of incident wave crests have great difference at different locations in the radial direction. High-frequency waves on the waveforms are observed. The time difference between incident and reflected wave peaks decreases significantly with r/R when r/R < 0.6, however, it almost keeps constant when $r/R{\geq}0.6$. The time duration between incident and reflected waves calculated by 3D FEM is approximately equal to that calculated by 1D wave theory when r/R is about 2/3.

• 인간식물환경학회지
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• 제23권2호
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• pp.233-243
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• 2020

This study collects social big data used in various fields in the past 9 years and explains the patterns of major keywords of the arboretums and botanical gardens to use as the basic data to establish operational strategies for future arboretums and botanical gardens. A total of 6,245,278 cases of data were collected: 4,250,583 from blogs (68.1%), 1,843,677 from online cafes (29.5%), and 151,018 from knowledge search engine (2.4%). As a result of refining valid data, 1,223,162 cases were selected for analysis. We came up with keywords through big data, and used big data program Textom to derive keywords of arboretums and botanical gardens using text mining analysis. As a result, we identified keywords such as 'travel', 'picnic', 'children', 'festival', 'experience', 'Garden of Morning Calm', 'program', 'recreation forest', 'healing', and 'museum'. As a result of keyword analysis, we found that keywords such as 'healing', 'tree', 'experience', 'garden', and 'Garden of Morning Calm' received high public interest. We conducted word cloud analysis by extracting keywords with high frequency in total 6,245,278 titles on social media. The results showed that arboretums and botanical gardens were perceived as spaces for relaxation and leisure such as 'travel', 'picnic' and 'recreation', and that people had high interest in educational aspects with keywords such as 'experience' and 'field trip'. The demand for rest and leisure space, education, and things to see and enjoy in arboretums and botanical gardens increased than in the past. Therefore, there must be differentiation and specialization strategies such as plant collection strategies, exhibition planning and programs in establishing future operation strategies.