실리콘폴리머의 혼합사용이 폴리비닐실록산 치과용 인상재의 물성에 미치는 영향

임창하 ( Chang Ha Lim ),김민강 ( Min Kang Kim ),김영철 ( Young Chul Kim ),박남국 ( Nam Cook Park ),송호준 ( Ho Jun Song ),박영준 ( Yeong Joon Park ) 한국고무학회 2009 엘라스토머 및 콤포지트 Vol.44 No.1

본 연구는 비닐작용기의 위치가 다른 실리콘 프리폴리머와 수소작용기의 위치가 다른 가교제, 그리고 이들의 혼합사용이 제조된 치과용 폴리비닐실록산 고무인상재의 물성에 미치는 영향을 연구하였다. 한 종류의 중점도 프리폴리머를 사용한 실험군은 인장강도, 파단신율, 압축시 변형률이 다른 특성의 프리폴리머들을 혼합사용한 경우보다 낮은 값을 보였다. 측부와 말단에 수소작용기가 있는 CR210 가교제를 사용한 실험군은 측부에만 수소작용기가 있는 CR101 가교제를 사용한 실험군에 비해 압축시 변형률과 파단신율이 더 높았다. 측쇄에도 비닐기를 갖는 높은 비닐함량의 프리폴리머를 사용한 경우는 더 높은 인장강도를 보였지만, 경화 속도가 늦어서 임상 사용에 적합한 작업성을 갖는 치과용 인상재를 만들기 위해서는 이 성분이 경화시간에 미치는 영향과 이를 조절할 수 있는 방안에 대한 지속적인 연구가 필요하다고 생각한다. The purpose of this study was to investigate the effects of combined use of several types of silicone polymers on the physical properties of the dental polyvinylsiloxane impression materials (PVS). Four types of silicone prepolymers having different molecular weight and vinyl group position, and two types of cross-linkers having differently located silyl hydride functional groups were used in various combinations for the formulation. The samples containing bimodal or trimodal prepolymers showed higher tensile strength, elongation at break, and elastic deformation than those containing only one type of prepolymer. The samples using CR210 cross-linker which has side-and terminal-silyl hydride groups showed higher elastic deformation and elongation at break than those using CR101 cross-liker which has side-only silyl hydride group. High vinyl content prepolymer having side vinyl group delayed setting even though it enhanced tensile strength. Further studies are needed to clarify the specific role of this component on setting time and to find appropriate controlling methods for making improved PVS with optimum workability.

소뇌성 운동실조증 환자의 후방 낙상 시 운동학적 특성

임창하(Lim, Chang-Ha),송용관(Song, Yong-Gwan),최수영(Choi, Su-Young),박진훈(Park, Jin-Hoon) 한국체육과학회 2017 한국체육과학회지 Vol.26 No.6

Falling occurs very frequently in patients with cerebellar ataxia (CA) and these falls are serious and often lead to injuries or a fear of falling. Therefore, fall prevention is essential for cerebellar patients. Effective compensatory stepping is important for preventing falls in patients with CA. The purpose of the present study was to examine the kinematic characteristics on compensatory stepping responses to recover balance comparing patients with CA and normal controls. A total of 22 individuals with CA and 10 age-matched normal controls participated in the study. We used a “lean-and-release” balance perturbation method to evaluate the balance recovery responses. The results indicated that cerebellar patients took longer to recover their body stability than normal controls. In the case of the first foot response, the reaction time of the patients was similar to that of the normal subjects, but they raised their feet higher. The range of movement of the body center of gravity was significantly larger than that of the normal controls during recovering their balance. In addition, patients with cerebellar disease exhibited a tendency to use multiple step, widened base of support, and inefficient first step movement strategies that make them to take more steps and move farther away during a posterior fall. This study reports the specific characteristic of stepping responses that can be utilized with effective rehabilitation program for cerebellar patients.

3D 입체영상을 활용한 활동관찰이 협응 동작학습에 미치는 영향

주창환(Ju, Chang-Hwan),임창하(Lim, Chang-Ha),박진훈(Park, Jin-Hoon) 한국체육과학회 2019 한국체육과학회지 Vol.28 No.6

Previous studies have used 2D images as a means of action observation methods. Due to the development of computer and video technology, however, 3D stereoscopic images have emerged and used in research. The purpose of this study was to investigate the effect of action observation with different types of visual feedback on coordinated movement learning. Sixteen individuals who had no experience in dance participated in the study. They practiced a whole-body coordinated pattern for 3 days using either 2D plane images or 3D stereoscopic images of Cucaracha dance movement. The results indicated that the magnitudes and angles of movement for each variable in 3D group tended to show higher values than 2D group. Thus, action observation using 3D stereoscopic images showed a tendency that such method has a positive effect on learning of coordinated movement, even though there was no statistical difference. Future studies need to be conducted considering the setting of the exercise period for the complexity of the task in action observation for motor skill learning.

다중 장애물의 인지적 과제 수행이 노인의 장애물 보행에 미치는 영향

윤정은(Yun, Jung-Eun),임창하(Lim, Chang-Ha),최상협(Choi, Sang-Hyup),박진훈(Park, Jin-Hoon) 한국체육과학회 2021 한국체육과학회지 Vol.30 No.5

It has been known that the presence of obstacles and deterioration of cognitive function contribute to increased fall rates in older adults. Although age-related changes in obstacle avoidance strategies in the elderly have been studied extensively, little is investigated about adaptive characteristics regarding how elderly people cross multiple obstacles under concurrent cognitive tasks. Nine healthy older and 9 young adults participated in the study. We examined how single or multiple obstacle conditions influence the planning and execution of obstacle avoidance performance under dual-task conditions. Elderly people demonstrated a longer stance time before crossing the first obstacle than young adults when the task complexity increased. These stepping characteristics were more evident in the dual-task condition. However, other gait outcomes were not significantly affected by the level of task complexity when compared with young adults. These results indicate that changes in task demands appeared to influence the planning of stepping strategies rather than the execution for obstacle crossing performance in healthy older adults.

지면 경사도에 따른 후방 낙상 시 소뇌성 운동실조증 환자의 자세제어 특성 연구

김대현(Kim, Dae-Hyun),임창하(Lim, Chang-Ha),임승진(Im, Seung-Jin),최상협(Choi, Sang-Hyup),윤정은(Yun, Jung-Eun),박진훈(Park, Jin-Hoon) 한국체육과학회 2018 한국체육과학회지 Vol.27 No.6

The Cerebellar damage leads to falls due to the impairments in balance control, and secondary damage is a terrifying factor that may cause injuries. Concerning the fear of falls in patients with cerebellar disease (CD), this study examined the kinematic characteristics on body control abilities such as the movements of the upper and lower limbs and the motion of stepping to recover the balance when a back fall is occurred with increased ground inclination. Eight patients diagnosed with CD and 8 age-matched normal controls (NC) participated in the study. We evaluated the ability to recover the balance independently through stepping movements by causing the situation of a backward fall with the lean-and-release method and four different ground inclination conditions. The results demonstrated that there were no differences between two groups in overall stepping characteristics such as total steps, initiation time and step distance. However, the distance between the foot and body COM was shorter and velocity of COM movement at landing of first step was higher in CD than NC as the ground inclination increased. These findings indicate that patients with cerebellar disease used an inefficient movement strategy that does not help to recover their trunk motion from falling when fear of falling is elevated.

신체활동에 참가하는 유소년들의 또래동기분위기, 스포츠우정과 내적동기의 관계

천승현(Cheon, Sung Hyeon),임창하(Lim, Chang-Ha),유경은(Yoo, Kyoung-Eun),주우영(Joo, Woo Young),송용관(Song, Yong-Gwan) 한국체육교육학회 2020 한국체육교육학회지 Vol.25 No.2

이 연구는 신체활동에 참가하는 청소년들의 또래동기분위기, 스포츠 우정과 내적동기의 관계를 규명하였다. 구체적으로 또래동기분위기 내 과제중심 동기분위기와 자아중심 동기분위기가 내적동기, 긍정적 우정과 부정적 우정에 어떻게 영향을 미치는지를 조사하였다. 연구목적을 달성하기 위해 서울 및 경기도 소재 초등학교와 중학교에 재학 중인 학생 560명을 대상으로 설문조사를 진행하였다. 수집된 자료는 통계 프로그램을 이용하여, 기술통계, 신뢰도 분석, 타당도 분석, 상관 분석과 회귀 분석을 수행하였다. 연구결과, 또래동기분위기 하위요인인 과제중심 동기분위기와 자아중심 동기분위기는 모두 내적동기와 정적 상관 및 영향력을 미치는 것으로 밝혀졌다. 과제중심 동기분위기는 긍정적 우정과 정적 상관 및 영향력을 지닌 것으로 밝혀졌으며, 부정적 우정과는 부적 상관 및 영향력을 미치는 것으로 드러났다. 이에 반해 자아중심 동기분위기는 부정적 우정과 부적상관 및 영향력을 미치는 것으로 나타났다. 이러한 결과는 과제중심 동기분위기가 긍정적인 우정 형성에 중요한 역할을 할 뿐만 아니라, 부정적 우정을 예방하는 데에도 중요하다는 사실을 보여준다. 결론적으로 긍정적인 스포츠 우정을 위해서 동료 간의 협력과 상호작용이 중요하다는 것을 교육 현장에 시사해주고 있다. Purpose: The purpose of this study was to examine relations between sport friendship, intrinsic motivation and peer motivational climate in the sport setting. Method: Students (n=560) aged 9-16 years old participated in this study completed the pack of questionnaires to sport friendship, intrinsic motivation and peer motivational climate. For the analyses, the SPSS and Amos program was used to test the research hypotheses proposed in this study. Results: Results showed that peer-created task-involving motivational climate was positively associated with intrinsic motivation and friendship. Whereas peer-created ego-involving motivational climate was weak-but-positively associated with intrinsic motivation and negatively with friendship. Conclusion: In overall, the findings showed that task-involving motivational climate created by peers in the youth sport context was a significant predictor of students’ motivation and sport friendship, while ego-involving motivational climate created by peers was able to be harmful of students’ motivation and friendship among peers themselves. More details and future directions were discussed.

전기근육자극 훈련이 복부비만 중년 여성의 복부지방, 체간 근 두께와 활성도에 미치는 영향

유승아 ( Seung-ah Yoo ),유기웅 ( Kee-ung Yoo ),임창하 ( Chang-ha Lim ),김창용 ( Chang-yong Kim ),김형동 ( Hyeong-dong Kim ) 대한물리의학회 2019 대한물리의학회지 Vol.14 No.2

PURPOSE: This study examined the effects of low frequency neuromuscular electrical stimulation (NMES) training on abdominal obesity in middle-aged women through electromyography and ultrasound. METHODS: Twenty-two middle aged women with abdominal obesity participated in the study. A low-frequency NMES device was used on the abdomen and waist of each subject for 20 minutes each (a total of 40 minutes) three times a week for eight weeks. The waist-hip ratio (WHR), weight and BMI (Body Mass Index) were measured. Electromyography (EMG) and ultrasound measurements were performed three times in total (pre-intervention, four weeks into the intervention, and eight weeks post-intervention) to examine the effects of low-frequency NMES on the abdominal muscle activity, muscle thickness, and subcutaneous fat. RESULTS: The results indicated a difference in the WHR and waist circumference before and after intervention (p< .05). The external oblique muscle (EO) showed a significant increase in muscle activity during all measurements taken post-intervention (p<.05). The abdominal subcutaneous fat thickness also showed a significant decrease between each measurement (p<.05). The test results showed that the abdominal subcutaneous fat thickness values taken eight weeks post-intervention were significantly lower than those taken pre-intervention and four weeks into the intervention (p<.05). CONCLUSION: These findings show that low-frequency NMES device training can be applied to middle-aged women with abdominal obesity to improve their body shape and exercise performance.

하지의 위치 제어 동작연습이 소뇌질환 환자의 운동학습에 미치는 영향

윤정은(Yun, Jung-Eun),송용관(Song, Yong-Gwan),임창하(Lim, Chang-Ha),최상협(Choi, Sang-Hyup),박진훈(Park, Jin-Hoon) 한국체육과학회 2018 한국체육과학회지 Vol.27 No.5

Impairments in distance control of lower limb movements are often major causes of motor handicap such as falls i n patients w ith cerebellar ataxia (CA). The a im o f this s tudy w as to investig ate motor learning ability for distance control of lower limb`s movement in CA patients. Twenty-four participants were divided into two groups: 12 patients with motor impairments due to cerebellar disease and 12 no-impairment control group. Participants were instructed to reach to targets presented at distance of 5cm or 15cm with right lower limb for acquisition of motor skill. Kinematic data were collected to determine movement accuracy from start position to target. The results showed that both groups showed significant improvement in learning target distances with their lower limbs even thought distance errors were higher in CA patients. Interestingly, individual group analysis for retention test indicated that even though the cerebellum is damaged, motor learning effects for lower limb movements were occurred in CA patients. These findings demonstrate that motor learning for distance control of lower limb can occur through repeated practice in CA patients suggesting feasibility for rehabilitation to enhance their control ability of lower limb movement.

상아질 결합제의 종류와 처리방법에 따른 전단결합강도와 상아질-레진 결합계면 미세구조에 관한 연구

임창하,이용렬,정영화,송호준,박영준 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1

The purpose of this study was to evaluate the dentin bonding agents (DBA) with the variations of the bonding system generations (4^th, 5^th and 6^th) and application methods by comparing the shear bond strengths (SBS) which were determined 24 h after application and dentin-adhesive interface microstructure. It was also aimed to suggest the theoretical clues for the adequate use of each bonding systems. The parameters were 1) generation of bonding systems (one product of 4^th, eight products of 5^th, and three products of 6^th generation), 2) moisture condition of the dentin surface after acid conditioning (moist group vs. dry group), 3) solvent type of the primers (three acetone-based, one acetone/ethanol-based, two water/ethanol-based, four water-based, one ethanol-based, one water/acetone-based), and 4) type of etchants (seven with phosphoric acid, three with self-etching primer, and one with 10-3 etchant). The results were as follows; One-bottle adhesives had comparable shear bond strengths compared to multiple component bonding agents, and some showed even higher results. Single Bond had the highest SBS value (20.6 ㎫) in the moist subgroup. For 4th and 5th generation DBAs, except for Mac Bond Ⅱ, all bonding systems showed lower SBS when dentin became desiccated after the conditioning-rinsing step, and generally shorter resin tags were produced in dry condition. Acetone-based adhesives generally showed better penetrability into dentinal tubules, and tended to be more sensitive to the degree of dentin dampness compared to those of the ethanol- or water-based adhesives. With Mac Bond Ⅱ which uses a self-etching primer, even though the hybrid layer was thin with a thickness of 1∼2 μ m, SBS was comparatively high. In the case of 6^th generation DBAs, Prompt L-Pop showed significantly lower SBS to dentin (7.4 ㎫) compared to those of AQ bond (13.3 ㎫) and One-Up Bond F (13.1 ㎫)(p<0.05). The hybrid layer was thin with a thickness of about 1μ m. In the case of AQ bond and One-Up Bond F, dentinal tubules were relatively well sealed. In the case of Prompt L-Pop, on the other hand, some of the dentinal tubules were not completely sealed, and fractured resin tags and separation between the hybrid layer and composite resin were observed. In the case of AQ bond, about 15μ m-thick resin layer was formed and many of the adhesive resin tags could not penetrate deep into the dentinal tubules. In the case of One-Up Bond F, many resin tags which are more than 50μ m-long were formed, but short penetration was also seen in some tubules. It is concluded that even though resin tag formation contributes in some extent for the bond strength, sufficient penetration of the adhesive resin to the exposed collagen meshwork and complete curing there in, and having sufficient strength to withstand the stress caused by the polymerization shrinkage during the light curing is essential for the success of the bonding procedure.