• 제목/요약/키워드: normal closure

검색결과 174건 처리시간 0.024초

Comparison between Subjective Scoring and Computer-Based Asymmetry Assessment in Facial Nerve Palsy

  • Lee, Doh Young;Kim, Hyun Seok;Kim, So Young;Park, Kwang Suk;Kim, Young Ho
    • Journal of Audiology & Otology
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    • 제23권1호
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    • pp.53-58
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    • 2019
  • Background and Objectives: The aim of the present study was to assess the feasibility of a PC-based facial asymmetry assessment program (PC-FAAP) and to compare the results of PC-FAAP with subjective regional scoring by raters in acute unilateral peripheral facial nerve paralysis (FNP). Subjects and Methods: Participants were divided into 3 groups with 8 participants per group: group I, normal; group II, mild to moderate FNP; and group III, severe FNP. Using the PC-FAAP, the mouth asymmetry ratio (MAR), eyebrow asymmetry ratio (EAR), and complete eye closure asymmetry ratio (CAR) were calculated by comparing the movement of tracking points on both sides. The FNP grading scale (FGS) integrated each score, and the scores were weighted with a ratio of 5:3:2 (MAR:CAR:EAR). Subjective regional scoring was measured on a 0-100 scale score by three otologists. PC-FAAP and subjective scoring were compared in each group regarding the consistency of the results. Results: The mean scores of the MAR, EAR, CAR, and FGS of each group were significantly different. PC-FAAP showed significant differences between the three groups in terms of MAR, EAC, CAR, and FGS. PC-FAAP showed more consistent results than subjective assessment (p<0.001). The PC-FAAP was significantly more consistent in group I and group III (p<0.001 and p=0.002, respectively). FGS in group III was the only parameter that showed a more consistent result in PC-FAAP than the subjective scoring (p=0.008). Conclusions: An FNP grading system using a PC-based program may provide more consistent results, especially for severe forms.

Comparison between Subjective Scoring and Computer-Based Asymmetry Assessment in Facial Nerve Palsy

  • Lee, Doh Young;Kim, Hyun Seok;Kim, So Young;Park, Kwang Suk;Kim, Young Ho
    • 대한청각학회지
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    • 제23권1호
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    • pp.53-58
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    • 2019
  • Background and Objectives: The aim of the present study was to assess the feasibility of a PC-based facial asymmetry assessment program (PC-FAAP) and to compare the results of PC-FAAP with subjective regional scoring by raters in acute unilateral peripheral facial nerve paralysis (FNP). Subjects and Methods: Participants were divided into 3 groups with 8 participants per group: group I, normal; group II, mild to moderate FNP; and group III, severe FNP. Using the PC-FAAP, the mouth asymmetry ratio (MAR), eyebrow asymmetry ratio (EAR), and complete eye closure asymmetry ratio (CAR) were calculated by comparing the movement of tracking points on both sides. The FNP grading scale (FGS) integrated each score, and the scores were weighted with a ratio of 5:3:2 (MAR:CAR:EAR). Subjective regional scoring was measured on a 0-100 scale score by three otologists. PC-FAAP and subjective scoring were compared in each group regarding the consistency of the results. Results: The mean scores of the MAR, EAR, CAR, and FGS of each group were significantly different. PC-FAAP showed significant differences between the three groups in terms of MAR, EAC, CAR, and FGS. PC-FAAP showed more consistent results than subjective assessment (p<0.001). The PC-FAAP was significantly more consistent in group I and group III (p<0.001 and p=0.002, respectively). FGS in group III was the only parameter that showed a more consistent result in PC-FAAP than the subjective scoring (p=0.008). Conclusions: An FNP grading system using a PC-based program may provide more consistent results, especially for severe forms.

무릎 관절경 수술 후 관절강내로 주입된 Ketamine의 효과 (Effect of Intraarticular Ketamine after Knee Arthroscopy)

  • 강건;신철호;이영희;조영우;박순은;손희원;조성도;박세훈
    • The Korean Journal of Pain
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    • 제18권2호
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    • pp.198-203
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    • 2005
  • Background: This study was designed to demonstrate the peripheral effect of ketamine on the synovia of the knee joint and evaluate the analgesic effect of an intraarticular ketamine injection following knee arthroscopy. Methods: In a double blind randomized study, 80 ASA class 1 or 2 patients were selected for elective arthroscopic knee surgery. The patients received either 20 ml of normal saline (Group C, n = 19), 20 ml of 0.5% ropivacaine (Group R, n = 21), 1 mg/kg of ketamine mixed with 20 ml of normal saline (Group K, n = 20) or 1 mg/kg of ketamine mixed with 20 ml of 0.5% ropivacaine (Group RK, n = 20), intraarticularly, just prior to wound closure. Postoperative pain was evaluated using a visual analogue scale (VAS 0 to 100) score at 1, 2, 6, 12, 24 and 48 hours after the intraarticular injection, with the side effects found in the four groups also evaluated. The patients' requests for rescue analgesic were recorded, total doses of tarasyn calculated and the overall patient satisfaction also evaluated. Results: The difference in the VAS scores for all time periods was not significant. The number of patients receiving rescue analgesics and the total doses received in Group C were greater than those for the other groups, but this was not significant. No side effects were observed in any of the patients. Conclusions: Ketamine and local anesthetics have been reported to have peripheral analgesic effects, with variable duration in the measurements of pain and hyperalgesia. However, we failed to demonstrate a peripheral analgesic effect on postoperative arthroscopic pain.

Royal jelly enhances migration of human dermal fibroblasts and alters the levels of cholesterol and sphinganine in an in vitro wound healing model

  • Kim, Ju-Young;Kim, Young-Ae;Yun, Hye-Jeong;Park, Hye-Min;Kim, Sun-Yeou;Lee, Kwang-Gill;Han, Sang-Mi;Cho, Yun-Hi
    • Nutrition Research and Practice
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    • 제4권5호
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    • pp.362-368
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    • 2010
  • Oral administration of royal jelly (RJ) promotes wound healing in diabetic mice. Concerns have arisen regarding the efficacy of RJ on the wound healing process of normal skin cells. In this study, a wound was created by scratching normal human dermal fibroblasts, one of the major cells involved in the wound healing process. The area was promptly treated with RJ at varying concentrations of 0.1, 1.0, or 5 mg/ml for up to 48 hrs and migration was analyzed by evaluating closure of the wound margins. Furthermore, altered levels of lipids, which were recently reported to participate in the wound healing process, were analyzed by HPTLC and HPLC. Migration of fibroblasts peaked at 24 hrs after wounding. RJ treatment significantly accelerated the migration of fibroblasts in a dose-dependent manner at 8 hrs. Although RJ also accelerated the migration of fibroblasts at both 20 hrs and 24 hrs after wounding, the efficacy was less potent than at 8 hrs. Among various lipid classes within fibroblasts, the level of cholesterol was significantly decreased at 8 hrs following administration of both 0.1 ug/ml and 5 mg/ml RJ. Despite a dose-dependent increase in sphinganines, the levels of sphingosines, ceramides, and glucosylceramides were not altered with any concentration of RJ. We demonstrated that RJ enhances the migration of fibroblasts and alters the levels of various lipids involved in the wound healing process.

단심실 -III C Solitus 형의 수술치험- (Surgical Repair of Single Ventricle (Type III C solitus))

  • naf
    • Journal of Chest Surgery
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    • 제12권3호
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    • pp.281-288
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    • 1979
  • For years, physicians and anatomists have been interested in the heart that has one functioning ventricle. Various terms have been suggested for this entity including single ventricle, common ventricle, double-inlet left ventricle, cor biatriatum triloculare, and primitive ventricle. In this report, the term "single ventricle" is utilized as suggested by Van Praagh, and is defined as that congenital cardiac anomaly in which a common or separate atrioventricular valves open into a ventricular chamber from which both great arterial trunks emerge. An outlet chamber, or infundibulum, may or may not be present and give rise to the origin of either of the great arteries. This definition excludes the entity of mitral and tricuspid atresia. An 11 year old cyanotic boy was admitted chief complaints of exertional dyspnea and frequent upper respiratory infection since 2 weeks after birth. He was diagnosed as inoperable cyanotic congenital heart disease, and remained without any corrective treatment up to his age of 11 year when he suffered from aggravation of symptoms and signs of congestive heart failure for 2 months before this admission. On 22nd of May 1979, he was admitted for total corrective operation under the impression of tricuspid atresia suggested by a pediatrician. Physical check revealed deep cyanosis with finger and toe clubbing, and grade V systolic ejection murmur with single second heart sound was audible at the left 3rd intercostal space. Development was moderate in height [135 cm] and weight[28Kg]. Routine lab findings were normal except increased hemoglobin [21.1gm%], hematocrit [64 %], and left axis deviation with left ventricular hypertrophy on EKG. Cardiac catheterization and angiography revealed 1-transposition of aorta, pulmonic valvular stenosis, double inlet of a single ventricle with d-loop, and normal atriovisceral relationship [Type III C solitus according to the classification of Van Praagh]. At operation, longitudinal incision at the outflow tract of right ventricle in between the right coronary artery and its branch [LAD from RCA] revealed high far anterior aortic valve which had fibrous continuity with mitral annulus, and pulmonic valve was stenotic up to 4 mm in diameter positioned posterolaterally to the aorta. Ventricular septum was totally defective, and one markedly hypertrophied moderator band originated from crista supraventricularis was connected down to the imaginary septum of the ventricular cavity as a pseudoseptum of the ventricle. Size of the defect was 3X3 cm2 in total. Patch closure of the defect with a Teflon felt of 3.5 x 4 cm2 was done with interrupted multiple sutures after cut off of the moderator band, which was resutured to the artificial septum after reconstruction of the ventricular septum. Pulmonic valvotomy was done from 4 mm to 11 mm in diameter thru another pulmonary arteriotomy incision, and right ventriculotomy wound was closed reconstructing the right ventricular outflow tract with pericardial autograft of 3 x 4 cm2. Atrial septal defect of 2 cm in diameter was closed with 3-0 Erdeck suture, and atrial wall was sutured also when rectal temperature reached from 24`C to 35.5`C. Complete A-V block was managed with temporary external pacemaker with a pacing rate of 110/min. thru myocardial wire, and arterial blood pressure of 80/50 mmHg was maintained with Isuprel or Dopamine dripping under the CVP of 25-cm saline. Consciousness was recovered one hour after the operation when his blood pressure reached 100 /70 mmHg, but vital signs were not stable, and bleeding from the pericardial drainage and complete anuria were persisted until his heart could not capture the pacemaker impulse, and patient died of low output syndrome 320 min after the operation.

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Ebstein 기형의 수술 -2례 보고- (Surgical Repair for Ebstein's Anomaly)

  • naf
    • Journal of Chest Surgery
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    • 제12권3호
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    • pp.289-296
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    • 1979
  • For years, physicians and anatomists have been interested in the heart that has one functioning ventricle. Various terms have been suggested for this entity including single ventricle, common ventricle, double-inlet left ventricle, cor biatriatum triloculare, and primitive ventricle. In this report, the term "single ventricle" is utilized as suggested by Van Praagh, and is defined as that congenital cardiac anomaly in which a common or separate atrioventricular valves open into a ventricular chamber from which both great arterial trunks emerge. An outlet chamber, or infundibulum, may or may not be present and give rise to the origin of either of the great arteries. This definition excludes the entity of mitral and tricuspid atresia. An 11 year old cyanotic boy was admitted chief complaints of exertional dyspnea and frequent upper respiratory infection since 2 weeks after birth. He was diagnosed as inoperable cyanotic congenital heart disease, and remained without any corrective treatment up to his age of 11 year when he suffered from aggravation of symptoms and signs of congestive heart failure for 2 months before this admission. On 22nd of May 1979, he was admitted for total corrective operation under the impression of tricuspid atresia suggested by a pediatrician. Physical check revealed deep cyanosis with finger and toe clubbing, and grade V systolic ejection murmur with single second heart sound was audible at the left 3rd intercostal space. Development was moderate in height [135 cm] and weight[28Kg]. Routine lab findings were normal except increased hemoglobin [21.1gm%], hematocrit [64 %], and left axis deviation with left ventricular hypertrophy on EKG. Cardiac catheterization and angiography revealed 1-transposition of aorta, pulmonic valvular stenosis, double inlet of a single ventricle with d-loop, and normal atriovisceral relationship [Type III C solitus according to the classification of Van Praagh]. At operation, longitudinal incision at the outflow tract of right ventricle in between the right coronary artery and its branch [LAD from RCA] revealed high far anterior aortic valve which had fibrous continuity with mitral annulus, and pulmonic valve was stenotic up to 4 mm in diameter positioned posterolaterally to the aorta. Ventricular septum was totally defective, and one markedly hypertrophied moderator band originated from crista supraventricularis was connected down to the imaginary septum of the ventricular cavity as a pseudoseptum of the ventricle. Size of the defect was 3X3 cm2 in total. Patch closure of the defect with a Teflon felt of 3.5 x 4 cm2 was done with interrupted multiple sutures after cut off of the moderator band, which was resutured to the artificial septum after reconstruction of the ventricular septum. Pulmonic valvotomy was done from 4 mm to 11 mm in diameter thru another pulmonary arteriotomy incision, and right ventriculotomy wound was closed reconstructing the right ventricular outflow tract with pericardial autograft of 3 x 4 cm2. Atrial septal defect of 2 cm in diameter was closed with 3-0 Erdeck suture, and atrial wall was sutured also when rectal temperature reached from 24`C to 35.5`C. Complete A-V block was managed with temporary external pacemaker with a pacing rate of 110/min. thru myocardial wire, and arterial blood pressure of 80/50 mmHg was maintained with Isuprel or Dopamine dripping under the CVP of 25-cm saline. Consciousness was recovered one hour after the operation when his blood pressure reached 100 /70 mmHg, but vital signs were not stable, and bleeding from the pericardial drainage and complete anuria were persisted until his heart could not capture the pacemaker impulse, and patient died of low output syndrome 320 min after the operation.

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금붕어 (Carassius auratus L.) 상처치유과정중 피부색소체계의 재분화에 관한 연구 (Redifferentiation of the Cutaneous Pigment System during the Wound Healing Process in the Goldfish, Carassius auratus)

  • 문명진;정문진
    • Applied Microscopy
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    • 제27권1호
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    • pp.71-86
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    • 1997
  • 상처치유과정중 관상어류 피부 색소체계의 재분화경로를 규명하기 위하여 외부 색채가 화려한 담수산 금붕어 (Carassius auratus L.)를 실험재료로 하여 피부의 일정부위에 인위적인 상처를 유도한 후, 시간 경과에 따른 조직과 색소 체계의 치유과정을 고배율의 투과 전자현미경으로 관찰하였다. 금붕어 피부 색소세포는 정상조직에서 황색소세포, 백색소세포 그리고 혹색소세포 등 세 종류의 진피성 색소세포로 이루어져 있었다. 황색소세포에는 pterinosome과 carotenoid vesicle 등 두 종류의 색소과립이 분포되어 있었고, 백색소세포와 혹색소세포에는 무정형 색소결정인 leucosome과 전자밀도가 높은 구형의 색소과립인 melamosome이 각각 함유되어 있었다. 초기 상처치유반응은 상처 유도직 후에 표면 손상부위로 전이되는 상피세포와 혈구세포에 의하여 수행되었다. 상처 유도후 $5\sim7$일이 경과된 조직의 표본에서는 조면소포체가 특이하게 발달되어 진피성 색소세포의 공통 원기로 추정되는 세포의 출현이 확인되었다. 또한 재생된 조직내에서 재분화된 색소세포는 상처유도 후 3주가 경과된 표본에서 처음 관찰되었다. 색소과립의 재분화 경로는 세포 내에서의 색소과립 형성 과정과 마찬가지로 색소세포내에 잘 발달된 조면소포체와 골지체를 경유한 후, 분비소포의 형태로 생성림이 확인되었다. 그리고 재분화된 색소세포로 유입되는 색소 원기물질은 음세포과립을 통하여 수송되었는데, 특히 조면소포체가 풍부한 원기세포와 연접된 색소세포의 원형질막에서 매우 활발한 물질의 수송이 관찰되었다. 한편, 각 색소세포의 일차적인 재분화과정은 상처 유도후 4주가 경과되어 피부 상처가 치유되는 시점을 전후하여 완료되었으나, 재분화된 색소세포의 수나 분포밀도는 충분한 체색발현을 위한 상태에 비해 크게 미달되는 것으로 분석되었다. 따라서 특별한 환경의 변화가 없는 한, 상처유도 이전의 색소체계와 동일한 상태로의 복구에는 적어도 3개월 이상이 소요되는 것으로 확인되었다.

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구개열환자에서 비인두공간과 비인강폐쇄부전과의 연관성 (RELATIONSHIP BETWEEN NASOPHARYNGEAL SPACE AND VELOPHARYNGEAL INCOMPETENCE IN CLEFT PALATE)

  • 조준희;최병재;심현섭;손흥규
    • 대한소아치과학회지
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    • 제27권4호
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    • pp.517-523
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    • 2000
  • 비인강폐쇄는 연구개, 인두측벽 그리고 인두후벽간의 움직임이 서로 조화되어 구강과 비강을 나누어주는 괄약근 기전으로서 연하, 호흡 및 발음 등의 생리적 기능에 중요한 역할을 한다. 이 기능에 문제가 생긴 경우를 비인강폐쇄부전이라하며 그 원인으로는 (1) 연구개의 길이 및 움직임이상, (2) 비인두강의 해부학적 공간문제, (3) 인두후벽과 측벽의 기능이상 등이 있다. 본 연구는 구개열 환자의 측면두부방사선 사진을 통해 비인두강을 해부학적으로 분석하고 동시에 산출된 각 모음의 과비음 정도를 평가하여 비인강폐쇄부전과의 연관성을 비교해 본 것이며, 얻어진 결과는 다음과 같다. 1. 연구개 길이는 정상인에 비해 현저히 짧았다. 2. adequate ratio는 정상인에 비해 작게 나타났다. 3. adequate ratio가 감소함에 따라 모음 조음시 anatomic mVPI가 점차 증가하였다. 4. 각 모음 조음시 anatomic VPI는 과비음정도와 비례관계를 보였다. 5. 고모음(/u/, /i/)의 과비음정도가 저모음(/a/)에 비하여 크게 나타났다. 결론적으로, 구개열환자에서 측면두부방사선 사진은 비인강폐쇄부전의 진단 및 평가에 유용하게 사용될 수 있으며, 비인두강의 해부학적 구조는 산출되는 과비음정도와 밀접한 연관성이 있었다.

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폐쇄용적(Closing Volume)이 증가된 만성 폐질환 환자에서 체위에 따른 폐환기량의 변화 (Effect of Posture on the Distribution of Pulmonary Ventilation in Patients with Increased Closing volume)

  • 김용태;김미경;임채만;고윤석;김우성;류진숙;이명혜;김원동
    • Tuberculosis and Respiratory Diseases
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    • 제40권6호
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    • pp.631-637
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    • 1993
  • 연구배경 : 정상 성인에서 폐환기는 균등하지 않아서, 평상호흡(tidal volume breathing)시 폐상부 보다 하부에서 환기가 더 많이 일어나는 것으로 알려져 있다. 한편 유아에서는 흉곽벽이 단단하지 못하여 폐에 대한 견인력이 부족하므로 평상호흡시 폐저부에 기도폐쇄가 일어나, 폐상부의 환기가 하부보다 더 많은 것으로 보고되었다. 또한 성인에서도 폐쇄용적이 증가하면 평상호흡시 폐하부에 기도폐쇄가 일어나 폐하부보다 폐상부에 환기가 더 많이 일어날 수 있을 것으로 예상할 수 있겠다. 방법 : 이에 연구자들은 이를 증명하기 위하여 정상대조군 및 만성 폐질환 환자군을 대상으로 폐활량측정법(spirometry) 및 폐쇄용적(dosing volume)을 측정하고 환기의 불균형은 체위에 따르므로 $^{133}Xe$ 폐환기주사($^{133}Xe$ ventilation scan)를 정와위(supine), 좌와위(left lateral decubitus) 및 우와위(right lateral decubitus)에서 시행하여 좌우 폐의 환기비를 측정하였다. 결과 : 1) 대상 환자는 정상 대조군 7명(평균 연령$62.9{\pm}6.1$세), 환자군중 폐쇄용적 정상인 6명(폐쇄용적 정상군)(연령 $62.8{\pm}8.2$세), 폐쇄용적 증가된 7명(폐쇄용적 증가군)(연령 $63.0{\pm}15.3$세)이었다. 2) 정상대조군에서 FVC는 평균(${\pm}$표준편차) 추정정상치의 $104{\pm}11%,\;FEV_1\;120{\pm}16%,\;FEV_1/FVC\;112{\pm}5%$, 폐쇄용적 $86.9{\pm}12.5%$으로 모두 정상범위 이었으며, 만성 폐질환 환자중 폐쇄용적 정상군에서는 FVC $62{\pm}11%,\;FEV_1\;54{\pm}17%$$FEV_1/FVC\;84{\pm}23%$로서 제한성 환기 장애 소견을 보였고 폐쇄용적 $92.6{\pm}15.5%$이었으며, 폐쇄용적 증가군에서는 FVC $53{\pm}9%,\;FEV_1\;38{\pm}13%,\;FEV_1/FVC\;69{\pm}16%$로서 폐쇄성 환기장애의 소견을 보였고, 폐쇄용적 $176.1{\pm}36.6%$로 환기용적 증가군에서 폐쇄용적이 유의하게 높았다(p<0.02). 3) $^{133}Xe$ 폐환기 주사상 좌측폐의 환기량이 정상대조군에서는 정와위시 총 환기량의 $48.1{\pm}5.3%$, 좌측 하위시 $54.1{\pm}9.8%$, 좌측 상위시 $40.9{\pm}6.5%$, 폐쇄용적 정상 폐질환군에서는 정와위시 $44.6{\pm}2.1%$, 좌측 하위서 $58.7{\pm}5.6%$, 좌측 상위시 $31.7{\pm}8.3%$, 폐쇄용적 증가 만성 폐질환군에서는 정와위시 $48.7{\pm}4.5%$, 좌측 하위시 $41.7{\pm}9.4%$, 좌측상위시 $60.9{\pm}15.7%$로서 정상대조군과 폐쇄용적 정상 만성폐질환 군에서는 좌측하위시 좌측환기량이 정와위시보다 유의하지는 않으나 증가하였고, 좌측상위시 좌측 환기량이 좌측 하위시보다 유의하게 감소하였으며, 폐쇄용적 증가군에서는 좌측 하위시 좌측의 환기량이 정와위시보다 유의하지는 않으나 감소하였고 좌측 상위시 좌측의 환기량이 좌측 하위시보다 유의하게 증가하여 양환자군 사이에 상반된 소견을 보였다. 결론 : 이상의 결과로서 폐쇄용적이 증가한 성인 만성 폐 질환 환자에서 평상호흡시 폐상부의 환기가 폐하부보다 더 많이 일어나는 것을 관찰할 수 있었다.

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공동이 있는 수직 분사 초음속 연소기 내의 불안정 연소유동 해석 (Numerical Analysis of Unstable Combustion Flows in Normal Injection Supersonic Combustor with a Cavity)

  • Jeong-Yeol Choi;Vigor Yang
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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    • pp.91-93
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    • 2003
  • A comprehensive numerical study is carried out to investigate for the understanding of the flow evolution and flame development in a supersonic combustor with normal injection of ncumally injecting hydrogen in airsupersonic flows. The formulation treats the complete conservation equations of mass, momentum, energy, and species concentration for a multi-component chemically reacting system. For the numerical simulation of supersonic combustion, multi-species Navier-Stokes equations and detailed chemistry of H2-Air is considered. It also accommodates a finite-rate chemical kinetics mechanism of hydrogen-air combustion GRI-Mech. 2.11[1], which consists of nine species and twenty-five reaction steps. Turbulence closure is achieved by means of a k-two-equation model (2). The governing equations are spatially discretized using a finite-volume approach, and temporally integrated by means of a second-order accurate implicit scheme (3-5).The supersonic combustor consists of a flat channel of 10 cm height and a fuel-injection slit of 0.1 cm width located at 10 cm downstream of the inlet. A cavity of 5 cm height and 20 cm width is installed at 15 cm downstream of the injection slit. A total of 936160 grids are used for the main-combustor flow passage, and 159161 grids for the cavity. The grids are clustered in the flow direction near the fuel injector and cavity, as well as in the vertical direction near the bottom wall. The no-slip and adiabatic conditions are assumed throughout the entire wall boundary. As a specific example, the inflow Mach number is assumed to be 3, and the temperature and pressure are 600 K and 0.1 MPa, respectively. Gaseous hydrogen at a temperature of 151.5 K is injected normal to the wall from a choked injector.A series of calculations were carried out by varying the fuel injection pressure from 0.5 to 1.5MPa. This amounts to changing the fuel mass flow rate or the overall equivalence ratio for different operating regimes. Figure 1 shows the instantaneous temperature fields in the supersonic combustor at four different conditions. The dark blue region represents the hot burned gases. At the fuel injection pressure of 0.5 MPa, the flame is stably anchored, but the flow field exhibits a high-amplitude oscillation. At the fuel injection pressure of 1.0 MPa, the Mach reflection occurs ahead of the injector. The interaction between the incoming air and the injection flow becomes much more complex, and the fuel/air mixing is strongly enhanced. The Mach reflection oscillates and results in a strong fluctuation in the combustor wall pressure. At the fuel injection pressure of 1.5MPa, the flow inside the combustor becomes nearly choked and the Mach reflection is displaced forward. The leading shock wave moves slowly toward the inlet, and eventually causes the combustor-upstart due to the thermal choking. The cavity appears to play a secondary role in driving the flow unsteadiness, in spite of its influence on the fuel/air mixing and flame evolution. Further investigation is necessary on this issue. The present study features detailed resolution of the flow and flame dynamics in the combustor, which was not typically available in most of the previous works. In particular, the oscillatory flow characteristics are captured at a scale sufficient to identify the underlying physical mechanisms. Much of the flow unsteadiness is not related to the cavity, but rather to the intrinsic unsteadiness in the flowfield, as also shown experimentally by Ben-Yakar et al. [6], The interactions between the unsteady flow and flame evolution may cause a large excursion of flow oscillation. The work appears to be the first of its kind in the numerical study of combustion oscillations in a supersonic combustor, although a similar phenomenon was previously reported experimentally. A more comprehensive discussion will be given in the final paper presented at the colloquium.

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