• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.160-176
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• 2017

The interaction of focused wave groups with a vertical wall is investigated based on the second order potential theory. The NewWave theory, which represents the most probable surface elevation under a large crest, is adopted. The analytical solutions of the surface elevation, velocity potential and wave force exerted on the vertical wall are derived, up to the second order. Then, a parametric study is made on the interaction between nonlinear focused wave groups and a vertical wall by considering the effects of angles of incidence, wave steepness, focal positions, water depth, frequency bandwidth and the peak lifting factor. Results show that the wave force on the vertical wall for obliquely-incident wave groups is larger than that for normally-incident waves. The normalized peak crest of wave forces reduces with the increase of wave steepness. With the increase of the distance of focal positions from the vertical wall, the peak crest of surface elevation, although fluctuates, decreases gradually. Both the normalized peak crest and adjacent crest and trough of wave forces become larger for shallower water depth. For focused wave groups reflected by a vertical wall, the frequency bandwidth has little effects on the peak crest of wave elevation or forces, but the adjacent crest and trough become smaller for larger frequency bandwidth. There is no significant change of the peak crest and adjacent trough of surface elevation and wave forces for variation of the peak lifting factor. However, the adjacent crest increases with the increase of the peak lifting factor.

• Physical Therapy Rehabilitation Science
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• 제11권3호
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• pp.356-362
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• 2022

Objective: Extracorporeal shock wave therapy (ESWT) is a nonsurgical treatment alternative to surgery for various musculoskeletal diseases that have traditionally been difficult to treat conservatively, including calcific tendinitis, tennis elbow, and plantar fasciitis. This study evaluated the effect of focused and radial shock wave therapy for calcific tendinitis of the shoulder. Design: Randomized controlled study Methods: Forty participants with calcific tendinitis were randomized into focused shock wave therapy (FSWT, n=20) and radial shock wave therapy (RSWT, n=20) groups. Patients were examined before and one week after treatment. Pain intensity was subjectively assessed using the visual analogue scale and function was assessed using the Constant-Murley score (CMS) and range of motion (ROM). Results: The results showed a significant decrease in pain and significant increase in shoulder mobility and function in both groups. However, FSWT was significantly more effective than RSWT, based on CMS and ROM assessment. Conclusions: Although it is possible to raise the energy intensity of RSWT to increase the depth at which the energy becomes dispersed, higher energy intensity is associated with a greater risk of severe neurovascular damage, and that high-intensity stimulation can cause adverse effects such as pain and petechiae. Therefore, FSWT is considered to be a safe and effective method for treating tendinous lesions while minimizing adverse effects. In conclusion, both FSWT and RSWT can reduce pain and increase mobility and function. FSWT can be considered as an alternative for calcific tendinitis of the shoulder.

• Physical Therapy Rehabilitation Science
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• 제3권2호
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• pp.142-147
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• 2014

Objective: This study aims to investigate high energy and low energy extracorporeal shockwave therapy (ESWT) and which one is more effective for shoulder pain. Design: Single blind randomized controlled trial. Methods: Fifty two subjects with upper trapezius (UT) trigger point (TrP) participated in this study. They were allocated to high energy (n=26) and low energy group (n=26). This study applies ESWT and investigates the changes of pressure pain threshold (PPT) and visual analogue scale (VAS). The high and low energy groups received focused piezo electric type ESWT 4 Hz, 1,000 pulses and 0.351 and $0.092mJ/mm^2$ respectively. Outcome measures of PPT and pain was measured by algometer and pain VAS. These measurements were performed before and after treatment. Results: The PPT value was significantly increased in both groups after treatment (p<0.05) and VAS scores were significantly decreased after treatment in both groups (p<0.05). However, there were no significant differences between groups. Conclusions: ESWT is an effective treatment for the application of the UT TrP. Although there were significant effects of extracorporeal shock wave therapy on PPT and VAS scores, there were no signficant differences between high and low energy extracorporeal shock wave therapy.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.47-54
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• 1995

This study was to measure the properties of logs and classify them by non-destructive methods. The purpose of this experiment was focused at mensurability of logs by non-destructive methods. The non-destructive instrument, Stress-Wave Timer 239A which was made by Metriguard in U.S.A., was used. The stress wave velocities of log's cross direction were measured and compared with three different methods; 1. with hammer, 2. with hammer and D.B.H. meter, 3. with manufactured instrument. Number of used logs were seven logs, which were classified by naked eye into six groups; very severe rot, severe rot, mild rot & knot, mild rot & check, mild rot, sound log, and in diameter were into three groups; large(57.4cm), medium(36~41.2cm), small(28.9cm) log. The results, which were classified by mensurability with non-destructive methods, were followed; 1. The stress wave velocities were very different between rot and sound log. So it meant the possibility of mensurability of logs by non-destructive method even if high standard error. 2. The stress wave velocities decreased with checks more than with rots, which meant the checks affected speeds more. 3. The stress wave velocities increased with knot. 4. The velocities with manufactured instrument showed lower standard error, so more accurate results than other methods. Especially the required labour decreased from 3~4 to 2 persons. 5. Finally, the mensurability showed more accurate results and made the classification of logs scientific.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.43-50
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• 1999

The safety-evaluation of ancient wood structures has been executed with only visual inspection. The application of NDE(nondestructive evaluation) is required because the visual inspection has many restrictions. Among many NDE techniques, the stress wave technique was used in this research. This study focused on evaluating the extent of decay in members of ancient structures, using stress wave nondestructive technique. For application of stress wave technique to ancient structures, the threshold time which divides members into categories according to degree of decay should be determined in advance. Stress wave timer (Metriguard Model 239A) was used in this study, specimens used in this research were the members obtained from six ancient structures. All specimens were identified as Hard Pine(Pinus densiflora S. et Z. or Pinus thunbergii P.) by microscope. Each member was tested with stress wave passing radially through the pith. In this study, the stress wave time of $12{\mu}s$/cm could distinguish between sound and decayed specimens with accuracy of 77.5 percent. Also, decayed specimens could be separated into moderate and severe categories by stress wave time of $20{\mu}s$/cm. Among the three decay location groups (exterior, mixed, interior), the exterior group could be classified into sound, moderate and severe decay with the greatest accuracy. Stress wave transit time was not sensitive to small decay pockets located in interior of the member.

• 복식
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• 제61권4호
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• pp.138-151
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• 2011

Due to its vast lands and rich underground resources, Mongolia is a country with high growth potential, even though it is currently in the early stage of economic development. In Mongolia, the Korean wave (Hallyu) has increased interests in Korea, especially in Korean fashion. This study analyzed lifestyles and examined the characteristics of clothing purchase behavior of Mongolian women in order to deepen the understanding of Mongolians' lifestyle and clothing purchase behavior and provide information for successful marketing strategies. The results based on 293 questionnaires showed that lifestyles consisted of six factors (socially active, beauty seeking, individualistic, simple comfort seeking, sensitive to others' perception, information focused) and four groups (socially oriented, individualistic, beauty seeking, and information seeking) were identified. Among the lifestyle groups, socially active group showed clear differences from other groups and there was no significant difference in demographic characteristics according to the lifestyle groups.

• 경영과정보연구
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• 제36권2호
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• pp.21-35
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• 2017

1990년대 이후 중국에서부터 시작된 한류는 전 세계적인 현상으로 자리매김하고 있다. 그러므로 최근 외국인 관광객 증가 흐름을 살펴보았을 때 방한 수요를 결정하는 거시적인 요인 외에 한류현상도 중요한 영향을 미치고 있음을 알 수 있다. 또한 방한 수요와 관련한 기존의 연구들이 연령별 차이를 두지 않고 전 세대를 포괄하거나 특정 세대만을 대상으로 분석하고 있다. 그러나 연령에 따라 한류에 영향을 받는 정도가 다르며 따라서 한류로 인한 방한수요가 연령별로 차이가 존재한다 할 수 있다. 본 연구는 한류가 외국인 관광객 방한에 미치는 영향을 분석하기 위해 한류지수를 이용하고 분석대상을 연령별로 세분화하여 실증분석을 시행한다. 분석 결과에 따르면 한류에 쉽게 영향을 받는 20대 이하가 한류로 인한 방한이 가장 많이 이루어지고 있다. 주목할 만한 사실은 50대 이상의 한류지수 추정계수가 30~40대 보다 높게 나왔다는 점이다. 이는 부모세대가 한류에 영향을 받은 어린 자녀와 함께 한국으로의 동반 입국이 이루어지고 있음을 의미한다. 본 연구를 통해 방한 선택에 있어 한류의 영향이 연령별로 차이가 존재하고, 세대별로 적절한 관광 마케팅 전략이 필요한 것을 알 수 있다. 예를 들어 모녀여행 상품처럼 한류에 영향을 받은 20대 이하의 자녀뿐만 아니라 함께 방한한 부모세대가 같이 즐길 수 있는 관광 상품을 개발해야 할 것이다. 또한 상대적으로 한류로 인한 방한이 적은 30~40대의 경우 다른 세대보다 본인에 대한 투자가 많은 세대이므로 한류를 통해 소개된 한국의 뷰티, 패션, 문화, 레저 등과 연계된 관광 상품을 개발할 필요가 있다.

• 한국콘텐츠학회논문지
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• 제18권1호
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• pp.154-163
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• 2018

우리나라뿐만 아니라 전 지구적으로 호우발생 빈도의 증가, 태풍이나 허리케인 세기의 강화 등에 따라 대규모 자연재해의 발생횟수와 피해액은 지속적으로 증가하는 추세이다. 태풍, 홍수, 호우, 강풍, 풍랑, 해일, 조수, 대설, 가뭄, 지진, 황사 등과 같은 자연재해는 발생지점과 규모를 예측하기 어려우며, 전조현상이 명확하게 나타나지 않아 대응에 많은 어려움이 존재한다. 그러나 자연재해의 피해규모를 예측할 수 있다면, 조기대응을 통해 피해를 저감할 수 있을 것이다. 따라서 본 연구에서는 국민안전처에서 발간하는 재해연보('91년~'15년)를 기반으로 서해연안지역의 풍랑피해함수를 개발하였다. 풍랑피해함수는 지역별, 시설별로 구분하여 개발하였으며, NRMSE는 1.94%~26.07%로 분석되었다. 개발된 식을 통해 피해규모를 예측하고, 그에 대한 적절한 대응이 이루어진다면, 피해를 저감할 수 있을 것으로 사료된다.

• 폴리머
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• 제26권3호
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• pp.353-359
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• 2002

본 연구에서는 고강도 초음파를 이용하여 분자량이 다른 poly(ethylene oxide) (PEO)를 증류수에 분산시켜 초음파 가진(加振) 시간이 PEO의 성질에 미치는 영향을 조사하였다. 고강도 초음파는 PEO 수용액 상에서 동공 형성 및 파괴를 일으켜서 PEO 거대 라디칼을 형성하였으며 이로인하여 PEO 자체의 유변학적 성질, 화학 구조 그리고 용융 거동이 현저하게 변화되었다. 초음파 가진에 의하여 PEO의 용융 점도는 감소되었고, 물과 PEO 사슬에서 비롯된 여러 종류의 라디칼들의 상호 작용으로 말미암아 새로운 말단기들이 생성되었다. 아울러 분자량에 따라 상이한 용융 거동을 나타내었는데, 상대적으로 분자량이 큰 경우에는 가진되지 않은 PEO에 비하여 결정화 속도가 느려지고 용융 피크의 강도가 감소되는 특성을 나타내었다.

• 생물정신의학
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• 제4권1호
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• pp.54-59
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• 1997

Objects : Sanjoin, the seeds of Zizyphus vulgaris var. spinosus has been used as the most important hypnotic agent in chinese medicine to treat insomnia. This research was performed in order to examine the effect of betulinic acid and sanjoinine-A which are components of Sanjoin. Method : Sleeping time, sleep recordings of EEG, EMG, serum serotonin level, and locomotor activity were measured in rats which received betulinic acid and sanjoinine-A as sleep induction material extracted from Sanjoin. Results : 1) Groups received betulinic acid, sanjoinine-A, and lorazepam showed increased sleep time than control group with saline. 2) Groups with betulinic acid, sanjoinine-A, lorazepam and saline recorded ${\beta}$-wave in sleep recordings of EEG. In EMG, there was no significant difference among all groups. 3) No significant difference in serum serotonin level among all groups was found. 4) In autonomic activity testing, groups of betulinic acid, sanjoinine-A, and lorazepam showed significantly more decreased in activity than saline group. In comparison of groups of betulinic acid and sanjoinine-A with a group of lorazepam, there was no significant difference. Conclusion : These results suggest that betulinic acid and sanjoinine-A have the sedative effect like lorazepam rather than sleep effect.