본 연구는 두경부의 자기공명 역동적(dynamic) 혈관조영술(DCE-MRA)에서 조영제(1.0 mol/ℓ)와 생리식염수의 희석 주입 비율에 따른 신호강도 차이를 비교 분석하였다. 연구 방법으로는 3.0 T MRI 장치에서 자동주입기를 이용하여 조영제와 생리식염수의 희석주입 비율(조영제:생리식염수)을 10:0 (1000 mmol/ℓ, 조영제 원액), 7:3 (700 mmol/ℓ), 5:5 (500 mmol/ℓ)로 3가지 군으로 하였다. 주입 조건으로는 오른팔 정맥으로 주입 속도 3.0 ㎖/sec으로 하였고 용량은 0.1 ㎖/㎏으로 하였다. 신호강도 측정은 동맥혈관 7 부위와 정맥혈관 2 부위로 하였고 역동적 영상에서의 측정 시기는 정맥이 침범하기 직전의 순수 동맥기, 최고신호 동맥기, 최고신호 정맥기로 구분 하였다. 연구 결과 최고신호 동맥기의 횡정맥동을 제외한 모든 측정 시기의 10:0 (1000 mmol/ℓ), 7:3 (700 mmol/ℓ), 5:5 (500 mmol/ℓ) 순서로 신호강도가 증가하였다(p<0.01). 따라서 두경부의 DCE-MRA에서 조영제와 생리식염수의 5:5 희석주입을 통하여 최고의 신호강도를 구현할 수 있고 최적의 영상을 얻을 수 있다.

본 논문에서는 불규칙 선수파랑 조건에서 선박계류시스템의 전후동요를 억제하는 연구를 수행하였다. 두점식 계류시스템은 비선형복원력의 특성으로 인하여 규칙파 조건에서도 강한 비선형 응답 특성을 보인다. 종방향 불규칙 장파가 외란으로 선박계류시스템에 작용하게 되면 규칙파 외력이 입사하는 경우보다 변위와 속도에서 더욱 복잡한 비선형 거동이 발생한다. 계의 종동요 변위와 속도를 동시에 억제하기 위하여 슬라이딩모드 제어법(SMC)을 적용하였다. SMC는 매개변수의 불확실성 및 외란에 대한 강인성을 갖는 폐루프 시스템을 제공하지만, 채터링은 이 제어법을 사용할 때 큰 단점이 된다. 본 연구에서는 준 슬라이딩모드의 시그모이드 함수를 이용하여 불규칙 해양파의 외란 조건에서 채터링을 줄이고. 수렴의 정확성에 도달하는 목표를 달성하였다. 제어법의 유효성은 수치시뮬레이션을 통해 증명하였다.

Background: Backward walking exercise may offer some unique and potentially beneficial differences compared with forward walking exercise. There is still a lack of research on backward walking exercises and forward head posture. Objects: The purpose of this study was to determine the effect of backward walking exercise on college students forward head posture in their 20s. Methods: Twenty-one subjects participated in the experiment. The subjects were those with a craniovertebral angle (CVA) of 55 degrees or less who understood the purpose and method of this study and voluntarily agreed. A camera capable of taking pictures of the lateral plane was installed at a distance of 1.5 meters before exercising. Pictures were taken before walking backward, and after walking for 15 minutes on the treadmill, the images were taken in the same way. The composition of the backward walking exercise was walking at a rate of 1.0 for 5 minutes, and the remaining 10 minutes were walking at a rate of 1.5. Wilcoxon signed rank test was used to compare CVA and craniorotational angle (CRA) before and after exercise. Results: As a result of this study, there was a significant difference in CVA before and after exercise (p < 0.05). There was a significant difference in CRA before and after exercise (p < 0.05). Conclusion: The backward walking exercise and verbal command seems to have positively influenced the changes in CVA and CRA among college students in their 20s. It seems that studies to confirm balance or muscle activity as well as changes in forward head posture through the long-term intervention of the backward walking exercise should be conducted.

월동배추 저장 특성과 이용 시 봄배추와의 차이를 비교하였다. 월동배추의 산업현장에서 저장 특성을 조사하여, 현장에 나타나는 현상과 개선 방향을 파악하고자 하였다. 월동배추인 ‘남도장군’을 산업현장에서 저온으로 그물망 저장을 하여 16주 동안 조사한 결과, 월동배추의 외관이 변하여 상품성은 떨어졌지만, 내부 상태는 양호하여, 신선배추로 판매보다는 가공용으로 이용 가능한 것으로 나타났다. 월동배추는 저장 중에 외관 및 생체중량, SPAD지수, 색상차에서 저장 동안에 지속적으로 감소하나, 8주까지 실증 현장의 배추는 신선 배추로 판매가 가능해 보였는데, 이후 저장 종료 시까지 월동배추의 겉잎 부패로 인한 손실로 신선하게 유통하기에는 부적합해 보였다. 그러나 저장 16주간의 실증에서 월동배추 내부의 경도, 당도 등 에서는 큰 변화가 없는 것으로 나타나서, 가공 시 다듬어 손질한다면 큰 문제는 없을 것으로 판단되었다. 월동배추인 ‘남도장군’을 저장 후 봄배추인 ‘춘광’과 결구의 개체 별 특성을 비교하였는데, SSC를 제외하고는 구중과 같은 특성에서 큰 차이를 보이지 않았다. 저장했던 월동배추가 절임 시 조사를 통해 pH를 제외한 염 특성이나 EC에서 차이를 보이지 않아, 봄배추와 비슷한 가공 적성을 가지고 있는 것을 확인하였다. 본 연구에서 월동배추의 저장 특성을 농산업 현장에서 실증하였고, 봄배추와 저장한 월동배추의 품질과 가공용으로 이용 시 특성을 비교 검토하였다.

Background: The alignment of the neck and shoulder is important in people with forward head posture. However, previous studies have mainly conducted fragmentary studies on the neck and shoulders, and studies on the combined movement of the neck and shoulders are incomplete. Objective: To investigate the effects of 6 week dynamic exercise program using Thera-band on craniovertebral angle (CVA) in adults with forward head posture. Design: Quasi-experimental study. Methods: The study was conducted on 24 adults with forward head posture and experimented with neck and shoulder exercises and divided them into groups of neck exercises, shoulder exercises, and neck and shoulder exercises to measure CVA values before and after the experiment. The neck exercise program included flexion and extension muscles of the neck and shoulder exercises included dynamic exercise of the upper extremities such as the trapezius muscles and serratus anterior muscle. The CVA results were measured using PA200. Results: Following the interventions, neck exercise group showed significant improvement in CVA (P<.05), but shoulder exercise group and combined exercise group did not show any significant results (P>.05). However, both groups showed some positive results. Significant differences were seen in the comparisons between the three groups (P<.05), and the results of the posthoc test showed significant differences in neck exercise group and shoulder exercise, neck exercise and combine exercise group. Conclusion: This study suggested that the Thera-band neck exercise is beneficial for foward head posture patients and is expected to be used in clinical trials.

Background: Due to aging, blood flow rate decreases, also posture and chewing habit may be changed. Objective: To identify that changes in blood velocity in the common carotid arteries (CCAs) in old persons with unilateral chewing habit (UCH) and forward head posture (FHP) in the elderly. Design: An observational cross-sectional study. Methods: Chewing habits, FHP, and CCAs velocities were assessed in 85 elderly subjects. Chewing habits were measured by visual observation. CCAs measured the peak systolic velocity (PSV), end-diastolic velocity (EDV), minimum diastolic velocity, and resistivity index. The subjects were divided into UCH and bilateral chewing habit groups depending on chewing habit. The subjects were also divided into >49 degrees and <49 degrees for comparison of blood flow between the left and right CCAs. Results: In the UCH, the chewing side had significantly higher EDV (P=.003), PSV (P=.023) than the non-chewing side. There was no significant difference in velocity between the CCAs in the FHP. Conclusion: This study shows that the blood flow velocity of the chewing side of UCH was higher, and unilateral chewing affects the CCAs velocity and thus highlight the importance of chewing habit in the elderly than head posture.

Engine components subjected to cyclic thermal and mechanical loads may experience low-cycle or high-cycle fatigue failures. In particular, both of these failures can easily occur in aluminum cylinder heads, which are exposed to high temperatures and combustion pressures. Predicting the fatigue characteristics of the cylinder head are very important in the design stage of engine development. In this study, a finite element analysis was performed to predict the low-cycle thermal fatigue around exhaust ports of the cylinder head. Temperature distributions are obtained through the heat transfer analysis considering thermal cyclic test. The analysis result involves large plastic deformations, indicating compressive stresses at high temperatures and subsequently turn into tensile stresses at cold conditions. And the results showed that the critical regions such as exhaust port with large plastic strains coincided well with crack locations from thermal cyclic test. Next, design changes were made to the critical areas of the exhaust ports, and the results showed that the durability was improved by about 60% over the initial model and there were no problems in the thermal fatigue test.

This study includes the clinical features of diabetic patients with fascial space infections of head and neck and those of non-diabetic patients. We retrospectively studied 62 patients who were treated for fascial space infections of the head and neck, and compared the patients’ background, the aetiology of the infection, clinical variables, laboratory values, and treatment process. Statistical analyses of the differences between groups were made with Student's t test, the chi square test, and analysis of variance, as appropriate. Diabetic patients had more spaces involved, had longer hospital stays, and developed more complications. The main microorganism of diabetic group was Klebsiella pneumonia and otherwise, Streptococcus spp. was for non-diabetic group. We conclude that diabetic patients are more likely to develop complications and it is necessary to consider about dominant microorganism when using medication for diabetes patients

Background: The importance of postural stabilization and cervical mobilization in subjects with pain from the anterior head posture is drawing more attention. However, studies on head and neck stabilizing intervention after mobilization are lacking. Objective: To examine the effects of Kinesiotaping and posture setting exercise on forward head posture (FHP). Design: Crossover Study Design Methods: The subjects were 17 male and female college students in their 20s with FHP. They were randomized into the Kinesiology taping group (KTG) with 9 subjects and posture stabilizing exercise group (PSEG) with 8 subjects. The intervention was conducted for 4 weeks, and changes in pain, craniovertebral angle (CVA), and proprioception were observed before and after intervention. Results: Pain was significantly reduced in the KTG and PSEG both before and after intervention. CVA and proprioception were significantly increased only in the PSEG. The differences in CVA and proprioception between the two groups were significant. Conclusions: These findings suggest that the application of posture setting exercise could decrease pain, proprioceptive error and increase CVA on FHP

목 적：자기공명영상 검사 시, 수신 코일에 의한 높은 신호강도 수집의 중요성이 점차 증대됨에 따라 다양하고 효율적인 수신 코일들이 개발되는 추세다. 즉, 수신 코일을 가볍고 유연하게 제작하거나 수신 코일과 인체 표면 간 거리조절이 가능하게 설계하여 다양한 크기나 모양을 가진 환자의 검사 부위에 최대한 밀착시켜 높은 신호를 수집할 수 있게 되었다. 따라서 본 연구에서는 다양한 환자를 고려하여 개발된 거리조절이 가능한 두부 수신 코일의 거리를 조절하여 수신 코일과 팬텀의 거리에 따른 신호강도를 비교하여 기존 코일과 비교해 실제 임상에서의 효율성을 알아보고자 하였다. 대상 및 방법：연구방법은, 수신 코일과 검사 부위 간 거리변화에 따른 신호강도를 측정하기 위해 성분은 같고 크기만 다른 2개의 원통형 팬텀을 사용하였으며, 수신 코일과 검사 부위 간 거리를 0cm부터 3cm까지 1cm씩 거리를 늘려 팬텀 영상을 획득하였다. 이때, 거리마다 ARC 가속 인자를 1-3까지 적용하여 수신 코일과 검사 부위의 거리변화 시, PI 기법 적용에 따른 신호 강도의 변화를 비교 측정하였다. 영상획득은 3.0T 초전도 자기공명영상장치와 48채널 Head Coil을 사용하여 병렬 영상기법을 적용한 표준 T1, T2 강조 영상을 획득하였고, 획득한 영상으로 NEMA 규격에 따른 감산 방법을 사용하여 신호와 잡음 데이터를 얻어 영상평가프로그램을 이용하여 영상의 신호강도를 측정하였다. 측정된 신호강도는 일원배치분산 분석과 사후분석을 이용하여 신호강도의 변화에 유의한 차이가 있는지 비교 평가하였다. 결과：연구결과, Large phantom과 Small phantom 모두 T2, T1 강조영상에서 거리가 가까울수록, PI 기법의 AF가 낮을수록 SNR이 증가했고 거리가 멀수록, AF가 높아질수록 SNR이 감소했다. 통계적 유의성을 알아보기 위해 일원배치분 산분석과 Duncan의 사후분석을 시행한 결과 유의수준 0.05에 대한 부 집단 중 Large phantom에서는 AF 1일 때 1, 2cm 에서 통계적으로 최대 SNR을 나타내는 0cm, AF 1과 유의한 차이가 없었다. 반면 Small phantom에서는 모든 그룹이 최대 SNR과 통계적으로 유의한 차이가 있었다. 결론：거리조절 두부 전용 코일을 사용할 경우 PI 기법을 사용하지 않는 일정 거리 내에서는 거리를 늘리지 않았을 때와 SNR의 강도에 통계적 차이가 없었다. 따라서 환자의 체격이 크거나 의료기구의 사용 등으로 거리를 증가시켜야 하는 경우 환자에게 불편함을 주지 않고 양질의 SNR을 가진 MRI 영상을 얻을 수 있을 것이라고 사료 된다

Background: Although previous researches have developed interventions for neck problems, headache, and temporomandibular disorder in patients with forward head posture (FHP), changes in masticatory muscle tone or stiffness as FHP worsening have not been investigated. Objective: To examine changes in masticatory muscle tone and stiffness through craniovertebral angle (CVA). Design: Cross sectional study Methods: The subjects were 21 healthy males with normal head posture. Three CVA were established for posture measurement in which the bilateral anterior temporal and masseter muscles were measured during the subjects maintained a series of postures. Results: The Right masseter muscle significantly increased in stiffness with advancing FHP (p < 0.05). No significant changes were observed in the muscle tone or stiffness of any other masticatory muscles, and no significant differences were found in bilateral masticatory muscle tone or stiffness in each measurement posture. Conclusions: This study suggests that the increased stiffness of the right masseter muscle as the FHP worsened requires consideration in physical therapy assessment and intervention.

거친 해상 조건에서 운항하는 선박은 파도와의 상대운동으로 인해 슬래밍 하중에 노출된다. 특히 선수가 자유수면으로 입수하는 과정에서 선체부는 일시적으로 큰 슬래밍 충격하중을 받게된다. 일반적으로 대형 컨테이너선박의 경우, 큰 플레어를 가지는 특징이 있으며, 이로 인해 플레어 슬래밍 충격하중으로 인한 구조적 손상이 발생할 수 있다. 본 연구에서는 슬래밍 수치시뮬레이션을 위해 먼저 신뢰할 만한 실험결과와의 비교검증을 수행하였으며, 선수 및 사파에서 선수플레어 슬래밍 하중을 추정하였다. 그 결과 슬래밍 하중이 발생 되는 위치는 0.975st이며, 최대 충격 하중은 선수파 조건에서 약 475kPa임을 확인하였다.

Background: Forward head posture (FHP) is a postural alignment of the cervical vertebrae that leads to increased gravitational load on cervical segmental motions. The overhead arm lift test assesses the ability to actively dissociate and control low cervical flexion and move the shoulders through overhead flexion. Objects: The purpose of this study was to explore muscle activities in the upper trapezius (UT), serratus anterior (SA), sternocleidomastoid (SCM), and lower trapezius (LT) alongside changes in head position during the overhead arm lift test in individuals with FHP. Methods: Fifteen subjects with forward head posture and fifteen subjects with normal subjcects were enrolled in this study. The patients performed the overhead arm lift test, and muscle activities of the UT, SCM, SA, and LT were measured using surface electromyography and by evaluating changes in head position. Independent t-tests were used to detect significant differences between the two groups and Cohen’s d was calculated to measure the size of the mean difference between the groups. Results: The FHP group demonstrated significantly increased muscle activity of the UT (32.46±7.64), SCM (12.79±4.01), and LT (45.65±10.52) and significantly decreased activity in the SA (26.65±6.15) than the normal group. The change in head position was significantly higher in the FHP group (6.66±2.08) than the normal group. Effect sizes for all parameters assessed were large between the two groups. Conclusion: The subjects with excessive FHP displayed were unable to fix their heads in position during the overhead arm lift test. The overhead arm lift test can thus be used in clinical settings to confirm control of the neck in these subjects.