• 한국지구과학회:학술대회논문집
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• 한국지구과학회 2005년도 추계학술발표회 논문집
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• pp.42-50
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• 2005

The electromagnetic (light) waves are limited to penetrate the media, ie, water and sea-bottom layers, due to high energy attenuation, but acoustic (sound) waves play as the good messenger to gather the underwater target information. Therefore the acoustic methods are applied to almost of ocean equipments and technology in terms of in-water and sub-bottom surveys. Generally the sound character is controlled by its frequency. In case that the sound source is low frequency, the penetration is high and the resolution is low. On the other hand, its character is reversed at the high frequency. The common character at the both of light and sound is the energy damping according to the travel distance increase.

• Journal of Welding and Joining
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• 제11권2호
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• pp.62-73
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• 1993

Weld pool oscillation for the full-penetration GTA welding process was investigated for its possible application to weld penetration control through theoretical modeling and experiment. Energy method was used to estimate the natural frequency of the molten pool having the physically-acceptable weld geometry and oscillation modes. An unique experimental system was built which had the data acquisiton and video capabilities so that the pool oscillation signals and molten pool surfaces could be monitored continuously. Pool oscillation was detected through arc voltage and arc light emission simultaneously. The signal from arc light emission showed good coherence with that from arc voltage, and arc light generated the higher quality signal. The molten pool was found to oscillate in different oscillation modes based on the travel speed and weld geometry. The natural frequency estimated from the theoretical model agreed reasonably well with the experimental results.

• 대한지역사회영양학회지
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• 제11권2호
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• pp.261-270
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• 2006

The purpose of this study was to identify the differences of older adults' perceptions of foodservice quality attributes of current offerings in Continuing Care Retirement Communities (CCRCs) in terms of their lifestyles (length of residency, special diet, housing option, travel frequency, dine out frequency), dining frequency, and demographics in the dining room of CCRCs. The survey was administered to residents in three CCRCs. Data was analyzed for 140 surveys using t-test, ANOVA, and factor analysis. This study found female older adults perceived the following attributes were more important than male ones: presentation of food, color and garnish, texture of vegetables, taste and flavor of food, and respectful attitude of serving staff. Older adults who have a special diet perceived the seasoning and bite sized pieces were more important than those who have a general diet. Also, there were significant differences between frequent visitors and occasional visitors in the dining room of CCRCs. By knowing the differences by residents' demographics and residential characteristics, the foodservice manager can establish strategies to increase the dining frequency of residents in the dining rooms of CCRCs.

• Journal of electromagnetic engineering and science
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• 제11권4호
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• pp.298-303
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• 2011

A capsular endoscope (CE) for inspection of the large intestine requires a motor for backward navigation against the autonomous travel in the intestine. This study proposes an HF power system for generating a magnetic field and for delivering wireless power to the internal or implanted medical devices. The magnetic field is generated by a wound coil (L) around a wooden frame, and the current is driven to the coil through a resonating capacitor (C). The characteristics of the resonance frequency shifting of the L-C series circuit are analyzed. A stable magnetic field intensity in the field coil is maintained by a specially designed frequency tracking system that automatically follows the L-C resonance frequency. Testing confirmed that the oscillation system tracks well the parameter changes of the electric components caused by the operating conditions or environmental variations.

• 한국생산제조학회지
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• 제19권3호
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• pp.419-425
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• 2010

To machine the micro hole, laser machining system is widely used, however, the system cannot fabricate the micro hole with high aspect ratio and good surface finish. To break the obstacles, the high frequency vibration mechanism with PZT (Piezoelectric Transducers) is proposed in this paper. The mechanism will vibrate the laser beam in vertical direction so that the aspect ratio and surface finish may be higher than the conventional. The mechanism vibrates the eyepiece of laser optics. In addition to the benefits, the mechanism enables us to have high precision and flexibility. It decreases burr and debris during machining. And it is able to machine various materials of workpiece. This research include high frequency and large travel range of the proposed mechanism. The PZT motion of mechanism and analysis on the sensitivity of design parameters are extracted from a finite element method (FEM) simulation. In the analysis, the target vibration mode without parasitic motion is designated to have the target frequency and high amplitude.

• Journal of Acupuncture Research
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• 제25권5호
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• pp.27-42
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• 2008

Objectives : The purpose of this study was to observe the effects of acupuncture and electro-acupuncture at $LR_3$ on intestinal motility in rat. Methods : We made over-activated state of intestinal motility with carbachol and suppressed state of intestinal motility with loperamide in rat and carried out needle retention acupuncture and high frequency electro-acupuncture at $LR_3$ in rat devided into pre-treatment group and post-treatment group. The charcoal travel rate was measured to evaluate the intestinal motility. Results : 1. High frequency electro-acupuncture at $LR_3$ have significant influences on intestinal motility of rat in normal state. 2. Pre-treatment of needle retention acupuncture, high frequency electro-acupuncture significantly decreased intestinal motility in rat which over-activated with carbachol. 3. Post-treatment of high frequency electro-acupuncture significantly increased intestinal motility in rat which suppressed with loperamide. Conclusions : These results suggest that acupuncture and electro-acupuncture at $LR_3$ are effective on intestinal motility in rat.

• 대한교통학회지
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• 제35권6호
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• pp.511-524
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• 2017

본 연구는 정책평가수단으로써 활동기반모형의 활용가능성을 평가하고자, 유연근무제(근무시간유연제 & 재택근무제)에 관한 시나리오 분석을 통해 교통부문에 미치는 영향을 분석하였다. 먼저, 첨두시간대의 통근통행량 분산을 통한 교통 혼잡 완화를 제외하고 근무시간유연제 적용 시 활동-통행 특성에 있어서 뚜렷한 변화는 없다. 자가용을 이용한 총통행거리(vehicle kilometer of travel, VKT)는 인구집단별로 가구 및 개인 특성에 따른 제약요소의 정도에 따라 서로 다른 결과를 나타냈다. 재택근무제에 따른 영향은 통근통행의 축소로 통행빈도와 거리가 감소하며, 재택근무자의 활동영역이 주거지를 중심으로 전환되면서 비동력 수단을 이용한 단거리 통행이 증가하였다. 따라서 자가용을 이용한 VKT가 감소되는 결과를 가져오며, 다만 수단 전환(타 수단 ${\Leftrightarrow}$ 자가용), (자가용을 이용한) 비업무통행의 증가 등으로 인해 인구집단별 VKT의 감소폭은 서로 다른 양상을 보인다. 연구를 통해 다음의 몇 가지 사항을 확인하였다. 첫째, 업무의 효율성을 높이기 위한 유연근무제가 직장인의 가구 및 개인의 특성에 따라 일상생활에 서로 다른 결과를 가져올 수 있으므로 사전에 인구집단별로 정밀한 영향평가가 필요하다. 둘째, ABM을 이용한 정책 평가에서 전반적으로 현실성 있는 결과를 도출하여 긍정적 활용가능성을 보여주었다. 셋째, 일반적으로 기존 모형에서 불가능했던 시계열 분석, 인구집단별 분석을 통해 정책평가에 있어서 보다 정밀한 분석의 가능성을 보여주었다. 마지막으로, 추가적인 자료 보완과 함께 문헌연구와 전문가 의견 수렴을 통한 시나리오의 완성도를 높여 향후 연구 결과의 정확도와 신뢰도를 높이는 후속 작업이 필요하다.

• 한국산림휴양학회지
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• 제22권4호
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• pp.23-33
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• 2018

본 연구는 한려해상국립공원 탐방객을 대상으로 여행경로에 따른 탐방특성 및 만족도 분석을 통해 국립공원 탐방관리정책 수립을 위한 기초자료를 마련하고자 진행되었다. 연구대상은 한려해상국립공원을 방문한 탐방객 총 671명이고, 현장조사 기간은 2017년 3월부터 11월까지 계절별로 봄, 여름, 가을 3차례 설문조사를 진행하였다. 주요내용은 탐방특성(방문동기, 여행경로, 탐방 소요시간, 참여활동 등)과 만족도(탐방 만족도, 재방문의향, 추천의향) 등이며, 한려해상국립공원 탐방객을 대상으로 자기기입식 설문지를 사용하여 조사하였다. 자료의 분석은 SPSS 21.0 프로그램을 이용하여 빈도분석, 독립표본 t-test 분석을 실시하였다. 분석결과 한려해상국립공원만 방문하는 단일목적지의 탐방객이 한려해상국립공원 이외에 다른 여행 목적지가 있는 다목적지의 탐방객보다 방문동기 중 건강증진, 휴양 휴식 치유를 위한 동기 항목에서 평균값이 통계적으로 유의하게 높게 나타났다. 거주지에서 국립공원까지 오는데 소요된 시간은 단일목적지 방문객이 다목적지 방문객 보다 소요시간이 적게 나타났다. 한려해상국립공원만을 방문한 단일목적지 탐방객의 탐방 후 만족도 평균값은 다목적지의 탐방객보다 통계적으로 더 높게 나타났으며, 재방문의향 및 추천 의향도 더 높은 것으로 나타났다. 본 연구결과는 한려해상국립공원 탐방객의 특성을 파악하여 효율적인 공원관리 정책을 마련하기 위한 기초자료를 제시하였다는 측면에서 연구의 의의가 있다.

• Journal of Acupuncture Research
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• 제25권4호
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• pp.11-29
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• 2008

Objectives : The purpose of this study was to observe the effects of acupuncture and electro-acupuncture at $LI_4$ on intestinal motility in rat. Methods : We made over-activated state of intestinal motility with carbachol and suppressed state of intestinal motility with loperamide in rat and carried out needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture at $LI_4$ or sham point in rat devided into pre-treatment group and post-treatment group. and we resulted as follow for measuring charcoal travel rate to observe intestinal motility. Results : 1. Any of needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture at $LI_4$ have no significant influences on intestinal motility of rat in normal state. 2. All of the pre-treatment and post-treatment of needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture didn't significantly decrease intestinal motility in rat which over-activated with carbachol. 3. Pre-treatment of needle retention acupuncture and high frequency electro-acupuncture significantly increased intestinal motility in rat which suppressed with loperamide. 4. Post-treatment of needle retention acupuncture, low frequency electro-acupuncture and high frequency electro-acupuncture significantly increased intestinal motility in rat which suppressed with loperamide. Conclusions : These results suggest that acupuncture on $LI_4$ have preventive effect and therapeutic effect on suppressed intestinal motility, and especially high frequency electro-acupuncture is more effective.

• 농업과학연구
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• 제44권1호
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• pp.123-132
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• 2017

Nowadays, many people suffer from stress because of their jobs, studies, traffic, etc. Daily stress may cause many diseases (Garrett, 1991). One of the methods for reducing stress is experiencing a natural environment (Frumkin, 2001). Cibodas botanical garden (CBG) is one of the most famous travel destinations in Bogor, Indonesia. CBG has the potential for tourism activities. However, an economic assessment is required to verify their sustainability. The research objectives of this study were to identify the characteristics of tourism utilization in CBG, to analyze the economic tourism value of CBG, and to measure the effectiveness of traveling to a natural environment for reducing stress. The research method used was the survey. This study used three data analysis methods: (1) descriptive analysis which was used to identify the characteristics of tourists, (2) travel cost method (TCM), and (3) contingent valuation method (CVM). Results showed some differences in the characteristics of foreign and domestic tourists respondents in age, educational background, income level, number of dependents, and the frequency of their visits. CBG has a high economic value, amounting to IDR (Indonesian Rupiah) 5,508,932,605,405 or approximately USD (United State Dollar) 413,000,000. WTP (Willingness to Pay) of domestic tourist respondents was IDR 29,702 or USD 2.2 per visit, while the value of foreign tourist respondents reached IDR 39,700 or USD 2.9 per visit. Respondents found it preferable to pay more for tickets (WTP value) than to buy medication to reduce their stress.