• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.2
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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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• v.11 no.3
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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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• v.3 no.2
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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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• v.23 no.2
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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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• v.27 no.4
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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.

• Journal of the Korean Society of Costume
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• v.61 no.4
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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.

• Management & Information Systems Review
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• v.36 no.2
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• pp.21-35
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• 2017

The Korea Wave has been spread out all over the world since 1990s. Therefore, it can be seen that the Korea wave phenomenon is one of determinants of international tourism demand for Korea in addition to the macro factors such as population, GDP per capita, exchange rate, distance, etc. Existing studies have focused on analyzing the impacts of the Korea wave on the international tourism demand for Korea by using the aggregated data. However, the impacts of the Korea wave inducing tourism vary in different age groups. In this study, we conduct empirical analysis in order to explore how different the effects of Korea wave on the demand of foreign tourists visiting to Korea in different age groups are. The estimation results show that the Korea Wave influences most on international tourism demand for Korea in the age group of the under-20s. Noticeable is that the estimated effects of the Korea Wave on international tourism demand for Korea in the age group of the over-50s are higher than those in the 30s and 40s. This indicates that the parent generations visit Korea together with their young children who are most affected by the Korea Wave. Through this study, it is necessary to develop strategies for tourism marketing linked to children and parents, and to develop tourism products to increase the number of foreign visitors to Korea in the 30s and 40s.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.154-163
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• 2018

Not only South Korea but also Global world show that the frequency and damages of large-scale natural disaster due to the rise of heavy rain event and typhoon or hurricane intensity are increasing. Natural disasters such as typhoon, flood, heavy rain, strong wind, wind wave, tidal wave, tide, heavy snow, drought, earthquake, yellow dust and so on, are difficult to estimate the scale of damage and spot. Also, there are many difficulties to take action because natural disasters don't appear precursor phenomena However, if scale of damage can be estimated, damages would be mitigated through the initial damage action. In the present study, therefore, wind wave damage estimation functions for the western coastal zone are developed based on annual disaster reports which were published by the Ministry of Public Safety and Security. The wind wave damage estimation functions were distinguished by regional groups and facilities and NRMSE (Normalized Root Mean Square Error) was analyzed from 1.94% to 26.07%. The damage could be mitigated if scale of damage can be estimated through developed functions and the proper response is taken.

• Polymer(Korea)
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• v.26 no.3
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• pp.353-359
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• 2002

High intensity ultrasound has been applied to a series of poly(ethylene oxide) (PEO)/water systems having different molecular weights of PEO. Major interest was focused on the effect of ultrasonic wane on the melt viscosity chemical structure and thermal properties of PEO. The expected role of ultrasound used in this study was to generate macroradicals of PEO chains by the formation and subsequent collapse of bubbles. It was found that the melt viscosity and chemical structure of PEO change significantly depending on the sonication time. For the prolonged sonication, PEO chains were significantly degraded and new end groups were formed by the interplay of various radical species. When the molecular weight of PEO was relatively higher, the crystallization rate was decreased and the intensity of the melting peak was reduced.

• Korean Journal of Biological Psychiatry
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• v.4 no.1
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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.