• Journal of Korean Society of Steel Construction
• /
• v.18 no.3
• /
• pp.385-393
• /
• 2006

In Korea, the effective utilization of wod structure is encour aged to preserve natural resources and the global environment.ote demand for wod. The efective combination of structural la minated timber and other materials is expected to extend the potential of building structures. This research examines the moment resis tance-type jointing method using structural laminated timber and H-section stel aiming at development of the two-direction frame for lar ge 9 mm and 12 mm) of the H section. Therefore, we conducted the experiment with bending test of the joints to investigate the s tifnes, strength, strain distributions of laminated timber an d of the flange of the H section, and failure paterns. As shown in the results, t he joints with a flange thicknes of 9 mm and 12 m have superi or strength with a flange thicknes of 9 mm and 12 mm were very large, whic h confirmed the high level of energy absorption of such structure s.

• Journal of the Korea Convergence Society
• /
• v.11 no.9
• /
• pp.277-285
• /
• 2020

The purpose of this study was to evaluate the effects of wearing Head-Mounted Display (HMD) on the cervical range of motion (CROM), neck muscle thickness, and pain in healthy young adults. The HMD group(male=16, female=7) was asked to perform sitting comfortably in a backless chair with hands on their knees with the HMD was worn on their heads to watch the video for 30 minutes. The control group(male=15, female=8) was asked to sit in the same posture as the HMD group for 30 minutes. CROM, neck muscle thickness, and pressure pain threshold (PPT) of both the upper trapezius and levator scapulae were measured before and after intervention. CROM and PPT of the upper trapezius and levator scapulae in the HMD group were significantly decreased and the thickness of the muscles in the HMD group were significantly increased more than in the pre-test (p<.05). There was no significant difference in CROM, muscle thickness, and PPT in the control group. Wearing HMD for a long time can cause a decrease in CROM and PPT and an increase in muscle thickness, and there is a risk of developing musculoskeletal disorders in the neck and shoulder. Therefore, this study recommends maintaining the correct posture of the neck and shoulder and using HMD only for an appropriate time.

• Journal of Korean Society of Forest Science
• /
• v.82 no.2
• /
• pp.122-127
• /
• 1993

This study was conducted to investigate characteristics related to lacquer yield and to evaluate possibility of indirect selection of Rhus verniciflua Stokes. Twenty-four lacquer trees were randomly selected for measuring growth, urushiol content and bark thickness. Urushiol content showed a significant positive correlation with outer bark thickness and secretory canal density at 1% level, and with inner bark thickness at 5% level. Bark thickness and secretory canal density could be used as indicators for high urushiol content within bark and thus for high lacquer yield. Mass selection for high lacquer yield was made based on urushiol content within bark. Sixteen individuals with the highest urushiol content value were selected for breeding. As expected, the selected trees had thicker bark, higher density of secretory canal, better developed secretory canals compare to the non-selected lacquer trees.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.2
• /
• pp.104-112
• /
• 2012

The failure of tenon in a traditional wood-framed structure may collapse of the entire structure. This study evaluates the strength and stiffness of tenon joints between the beams and pillars through experimental study and suggests reinforcing method of the tenon joint without dismantling the main structures. The main experimental parameters are the number, distance, shape, and inserting depth of spiral-shaped reinforcing steels. As the thickness of the tenon in beams increases, the strength and the initial shear stiffness of the joint increases and, however, the tenons in pillar becomes weaker, resulting in the safety problem of the structure. It is recommended that three spiral-shaped reinforcing steels be placed in the central parts of the tenon to effectively improve the strength and the shear stiffness of the joint.

• The Journal of the Korea Contents Association
• /
• v.11 no.12
• /
• pp.326-334
• /
• 2011

The aim of the study was to investigate the thickness of deep neck muscles during neck endurance tests using ultrasonography images to assess muscle sizes in persons with or without neck pain experience. Sixty-five university students volunteered for the study. The thicknesses of longus colli, longus capitis, semispinalis and cervical multifidus were assessed bilaterally using diagnostic ultrasound equipment during each endurance test. Participants were divided into two groups based on their Neck Pain(NP) experience; 45 subjects of those had no experience of NP (Group1) whereas 20 subjects of those reported NP experience sometime in their lives (Group2). Endurance time of both neck flexion and extension tests in Group1 showed significantly longer than Group's (p<0.01). The thicknesses of deep neck flexors and extensors were observed smallest at the terminal of endurance tests in general. Only left longus colli was found to be significantly smaller at rest in subjects of Group2 than Group 1's (P=0.02). The size difference between at contraction and the terminal of right longus capitis was observed bigger in subjects of group1 than subjects in group2. Future studies are needed to conduct with clinical subjects to assess contraction patterns of neck muscles.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.659-666
• /
• 2021

This study aimed to investigate the effect of changes in pressure levels and gaze directions on deep neck flexor muscle thickness. Twenty-seven subjects participated in this study. Ultrasound imaging of the longus colli (LC) and sternocleidomastoid (SCM) were measured in four gaze directions (0°, 20°, 40°, 60°) and five pressure levels (20 mmHg, 22 mmHg, 24 mmHg, 26 mmHg, 28 mmHg) during cranial-cervical flexor (CCF) exercises. Repeated ANOVA was performed for analysis of muscle thickness difference according to gaze direction and pressure levels in LC and SCM. Results: LC showed a significant difference between 0° and 20°, 0° and 40°, and 0° and 60° at pressures of 20 mmHg and 22 mmHg (p<.05). SCM displayed a significant difference between 0° and 20°, 20° and 40°, and 40° and 60° at 28 mmHg (p<.05). In this study, it was found that setting the gaze direction to 20° for the CCF exercise can increase the activation of LC and lower the activity of SCM to obtain the effect of exercise. Based on the results of this study, it is hoped that the beneficial effects of the CCF exercise can be increased by setting an optimal gaze direction in a clinical environment.

• Conservation Science in Museum
• /
• v.12
• /
• pp.47-52
• /
• 2011

The authors did conservation treatment of wooden objects excavated from Isong Sanung Fortress upon request of the Museum of Hanyang University. The authors investigated types of the trees prior to conservation treatment to find out 1 Pinus spp. and 11 Querus spp. The authors investigated paint coating of 1 wooden ware to find out No.4 of the exterior and No.3 of the interior and about 100㎛ thickness of the lacquer layer. The. conservation treatment was done to immerse wooden ware into high molecular PEG#3,350 in water solution (10 ~ 45%) and to give physical strength and to do vacuum freeze drying.

• Journal of the Korean Wood Science and Technology
• /
• v.33 no.1 s.129
• /
• pp.7-16
• /
• 2005

This study was carried out to evaluate the structural property of double shear bolted connections in Korean Larch. For the main member, sawn lumber and Glulam were used in which thickness of lumber is 39 mm, 89 mm, 139 mm, 189 mm and Glulam 80 mm, 140 mm, 170 mm. For the side member, sawn lumber and steel plate were used in which thickness of lumber is the same of the main member and steel plate is 6mm. And connections were jointed by M12, M16, M20 bolts which were usually used for wood constructions in Korea. Directions of loading to connections were perpendicular and parallel to grain of main and side member. First, through the dowel bearing test, the dowel bearing strength was evaluated and through the bolt bending tests, the bolt bending strength was evaluated. And then experiments for the connection were performed. Obtained results from experiments were compared with calculated values by EYM and analyzed. Strength of double shear bolted connections in Korean Larch was similar or higher than calculated value by EYM. Especially when the side member was made by the sawn lumber, it was similar to the calculated value. In failure mode, the mode was effected by the knot and the dry defect. In the thin main member, it was shown mode I and as the thickness of the main member was thicker, it was changed into mode III.

• Journal of Korean Society of Forest Science
• /
• v.55 no.1
• /
• pp.1-21
• /
• 1982

The pollen morphology of 2 forms, 6 varieties, 50 species, 15 genera, 11 families of Korean Sapindales was studied. The keys were provided for general and families of Korean Sapindales. General pollen morphology was diversed and taxonomically significant differences were obtained in shape, aperture, type and size, sculpture pattern and exine thickness of pollen grains. Pollen grains of Korean Sapindales could be grouped into four types and five subtypes. One of five sub-types pollen grains of Acer could be ground into four under subtypes: ginnala type, barbinerve type, psseudo-sieboldianum type and negundo type. Pollen morphology of Empetraceae, Buxaceae and Balsaminaceae appeared to have very special features in the equatorial view and aperature type compare with pollen grain of the other families of Korean Sapindales.

• Korean Journal of Environment and Ecology
• /
• v.14 no.1
• /
• pp.80-87
• /
• 2000

구상나무림 보전관리의 기초자료를 마련하고자 지리산 한라산 및 덕유산의 아고산지대에 95개의 조사구를 설치하여 한국특산종 구상나무의 생육현황과 구상나무 서식지의 입지인지를 조사하였다 구상나무는 흉고직경 10-30cm의 범위에 드는 나무들이 주로 고사목으로 나타났으며 고사목의 비율은 전체적으로 총개체수의 11.51%였다 고사목의 비율또한 덕유산에서 18.18%로 가장높게나타났고 한라산 지역이 8.11%로 가장 낮게 나타났다 조사구당 구상나무 개체수 치수의 개체수 구상나무의 수고와 흉고직경 생육현황표에 의한 점수 구상나무의 상대밀도 등은 지역간에 통계적 유의차가 인정되었다 생육중인 구상나무의 활력은 한라산 지리산, 덕유산으로 순으로 좋았다 조사구당 구상나무 치수의 개체수는 한라산에서 6.00개체로 가장 많았으며 덕유산에서는 치수가 없는 것으로 나타났다 구상나무의 상대밀도도 한라산, 지리산, 덕유산 순으로 높게 나타났다. 조사구당 구상나무 개체수는 해발고와 정의 상관, 방위, 낙엽퇴의 두께, 조사구당 교목의 개체수 및 종수, 활엽수 상대밀도와는 부의 상관이 인정되었다. 구상나무 상대밀도는 해발고와는 고도의 정의 상관관계 방위 조사 구당교목의 개체수 및 종수 수관울폐도, 활엽수 상대밀도와는 부의 상관관계가 인정되었다 지리산, 한라산 및 덕유산에 자생하는 구상나무는 해발고가 높으며 볕이 잘들고 낙엽퇴가 얕으며 종구성이 단순하고 활엽수가 적은 지역에 보다 많이 분포한다.