• 대한기계학회논문집B
• /
• 제28권4호
• /
• pp.415-424
• /
• 2004

Cooling the electronic equipment is one of the major focal points of the design process and the key to successful product launch. The two-phase loop thermosyphone which is a good candidate among many available options was investigated fur cooling of the high power amplifiers. The system is composed of evaporator which contains 6 parallel cold plates, fan cooled condenser, gas-liquid separator, and interconnecting tubes. Experiments were performed for several refrigerant charging values, hs and as a experiment result, the optimum charging value fur this system was proposed. In order to optimize the system design, the operating cycle pressure and inlet/outlet temperatures of evaporator and condenser are measured and analyzed. The effect of the three parameters such as flow rate and temperature of condenser cooling air, and thermal load on the evaporator are investigated. The lower the operating pressure and the cycle temperatures are also better to prevent the leakage of the system. The system invesigated in this paper can be directly used for cooling of a real unmanned wireless communication station.

• Journal of Chest Surgery
• /
• 제8권2호
• /
• pp.125-134
• /
• 1975

The record of 137 patients with spontaneous pneumothorax seen at Busan National University Hospital during past 3years were reviewed to study the possible pathogenesis and its effective management. and the results obtained as follows; 1] The incidence of the "spontaneous" pneumothorax which developed without underlying pathology was 13-1%. The majority of those cases was considered as the result of rupture of subpleural blebs. 2] The incidence of secondary pneumothorax which developed with underlying pathology was 50.0%, in which 42.3% was combined with pulmonary tuberculosis and 8, 0% was combined with pulmonary infection. The traumatic pneumothorax was developed in 36-5% of total series. 3] In age distribution, there was pronounced difference between spontaneous and secondary pneumothorax. The majority of spontaneous pneumothorax cases was 20-30 decade and tall and tall and thin in body structure. In secondary pneumothorax, however, the incidence was relatively high in age group more than 50 years old. 4] The incidence of pneumothorax combined with pulmonary tuberculosis was particularly high in our country, and the cause of pneumothorax was seemed due to the rupture of subpleural caseous foci in some cases, but the majority was seen due to the rupture of emphysematous blebs which were formed with a pathological process of chronic tuberculosis. 5]Closed [tube] thoracotomy was the main therapeutic approach of choice in the great majority ,of pneumothorax in our series with the relapse rate of 19.6%. However, open thoracotomy and adequate surgical procedures should be undertaken in patients with continuous air leakage over 7 days and recurrent attack of pneumothorax.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.1350-1357
• /
• 2010

In tunnelling, temporary ventilation is very important factor in the safety of worker and the work efficiency which is affected by visibility. There are a lot of problems in the recent tunnel construction, because the longer the tunnel, the more the present design doesn't satisfy the allowable standard about dust and air pollution. Especially, In case the length of tunnel is more than 1,000m, the ventilation efficiency tends to decrease. In this study, the field measurement of the degree of contamination was performed near the face of tunnel. Based on the results obtained, the main factors of problem in temporary ventilation are the difference of temperature between outside and inside, the rate of leakage of ventilation duct and the dust and so on. It maybe helpful to the solution of problems, and also the accurate ventilation estimate.

• Journal of Chest Surgery
• /
• 제24권8호
• /
• pp.757-764
• /
• 1991

We have observed 360 cases of spontaneous pneumothorax from January 1980 to May 1991 at the department of Thoracic and Cardiovascular Surgery, Chosun University Hospital. Males occupied 266 cases[73.9%] and females 94 cases[26.1%], and its ratio was 2.8: l. The age of patients ranged from neonate[5 days] to 84 years old. The site of pneumothorax was right in 50.3%, left in 43.3% and bilateral in 6.4%a. The clinical symptoms were frequently dyspnea, chest pain and coughing. The associated pulmonary lesions were shown pulmonary tuberculosis in 199 cases[55.3%], bullae in 54, pulmonary emphysema in 31, COPD in 17, pneumonia in 6, lung cancer in 5, paragonimiasis in 5, catamenial pneumothorax in 3 and unknown underlying pathology in 39 cases. The results of surgical management of spontaneous pneumothorax are followings: 288 out of 360 cases[80.0%] were cured by closed thoracotomy, 53 cases[14.8%] were cured by open thoracotomy. Open thoracotomy was the most effective procedure in persistent air leakage, recurrent pneumothorax, visible bleb or bullae on the chest X-ray, associated lesion, bilateral simultaneous pneumothorax, parenchymal incomplete lung expansion and bleeding after closed thoracotomy. The incidence of complication was developed in 10. ado and recurrent rate was seen in 10.6%. There was no operative death.

• 한국공작기계학회논문집
• /
• 제15권4호
• /
• pp.63-68
• /
• 2006

This research presents the reliability analysis of the pneumatic actuator within the tape feeder that is used to transfer the correct force to linked parts during l.0E+7 cycles. First, the degradation analysis for thrust and air leakage is executed to obtain the failure data of a product based on its performance over time. Second, once the parameters has been calculated using the weibull 2-parameter distribution and MLE(Maximum Likelihood Estimation), information related to life such as reliability, failure rate, probability density function is estimated. Finally, MTTF(Mean Time To Failure) and $B_{10}$ life of actuators are calculated. MTTF means the mean life at the confidence level and $B_{10}$ life refers to the time by which 10% of the product would fail. In this study, failure causes and solutions are examined using the reliability analysis.

• Journal of Chest Surgery
• /
• 제33권3호
• /
• pp.245-251
• /
• 2000

Backround: Pulmonary aspergilloma is a potential life-threatening disease resulting from massive hemoptysis. Pulmonary aspergilloma has been treated surgically for many years, however, it has also had higher risk of mortality and complication rate. The purpose of this study is to analyze the operative methods and the types of complications. Material and Method: Sixty patients who underwent surgical resection for pulmonary their medical reconrds. Result: The mean age was 46.3$\pm$13.4 years(range 20 to 76 years). The most common clinical presentation was hemoptysis which occurred in 48 patients(80%). Pulmonary tuberculosis was the most common pre-existing disease, occurri9ng in 28 patients(46.7%). The other associated lung diseases were bronchiectasis(n=11), silicosis(n=2), and chronic pnumonia(n=1). Operative proceudres wer lobectomy in 35 patients, pneumonectomy in 6, segmentectomy in 5, lobectomy and thoracoplasty in 3, segmentectomy and thoracopasty in 1, and cavernostomy in 10. The operative mortality was 6%(n=3) in lung resection patients but 0% in cavernostomy patients. The most common complications were prolonged air leakage, wound infection and postoperative bleeding. Conclusion: In most cases of pulmonary aspergilloma surgical resectin remains the only effective therapy. However, cavernostomy may be more effective for pulmonary aspergilloma patients with decreased pulmonary functions and for patients with high risk for lung resection.

• Journal of Chest Surgery
• /
• 제28권12호
• /
• pp.1132-1138
• /
• 1995

From 1991 to 1994, we experienced 24 cases of neonatal pneumothorax who were admitted to the Neonatal Intensive Care Unit[NICU , Chosun University Hospital. The Following results were obtained.1 The incidence of neonatal pneumothorax was 0.70%, and there were 8 spontaneous pneumothoraces and 16 secondary pneumothoraces. 2 The clinical manifestation of neonatal pneumothorax was as followed. Male infant was dominant[M:F=2:1 , the onset was within 24 hours in the majority[83% , and the right side[62% was more frequent than the left side. The gestation duration and birth weight show no correlation with underlying neonatal pneumothorax. The pulmonary diseases were meconium aspiration syndrome and hyaline membrane disease, and the incidence of those was 58%. Meconium aspiration syndrome occurred earlier than hyaline membrane disease. Symptoms and signs were tachypnea[46% , cyanosis[21% , irritability[13% , chest retraction[8% and apnea[8% .3 The treatments performed were oxygen therapy[17% , thoracentesis[4% and closed thoracostomy with underwater seal drainage[79% . The Mean duration of air leakage was 11.7 hours, and the mean drainage time was 4.35$\pm$1.3day. 4 The overall hospital mortality was 33%, and the rate of complication was 46%. The complications were metabolic acidosis, atelectasis, pleural effusion, pulmonary hemorrhage and pneumonia. We concluded that the prognosis was related to the underlying pulmonary disease.

• 태양에너지
• /
• 제15권3호
• /
• pp.119-125
• /
• 1995

지금까지 우리는 건물분야에서의 합리적인 에너지 사용을 위하여 건물외피의 단열성능을 향상시킴으로써 열손실을 줄이려는 데에 주력하여 왔으며, 침기로 인한 열손실을 줄이려는 노력은 상대적으로 미흡하였다. 그러나, 침기로 인한 난방에너지의 소비가 상당량에 이르는 것으로 조사됨으로써 재실형태에 따라 최소환기기준을 만족시키면서 침기에 의한 불필요한 에너지의 손실을 줄이려는 노력이 매우 유효한 것으로 평가되고 있다. 실제로 침기에 의한 불필요한 에너지의 낭비가 얼마나 되는가를 평가하기 위해서는, 건물에서의 침기율을 정확하게 측정할 수 있는 방법이 전제되어야 한다. 본 연구에서는 감압/가압법의 일종인 Blower Door System을 사용하여 공동주택에서의 기밀성능을 측정, 평가함은 물론 측정결과를 토대로 합리적인 수준까지 기밀화할 경우 난방에너지의 절약가능성에 대하여 추정하였다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.369-374
• /
• 2006

Quantification of infiltration rate is an important issue in HVAC system design. The infiltration in buildings depends on many uncertain parameters that vary with significant magnitude and hence, the results from standard deterministic simulation approach can be unreliable. The authors utilize uncertainty analysis In predicting the airflow rates. The paper presents relevant uncertain parameters such as meteorological data, building parameters (leakage areas of windows, doors, etc.), etc. Uncertainties of the aforementioned parameters are quantified based on available data from literature. Then, the Latin Hypercube Sampling (LHS) method was used for the uncertainty propagation. The LHS is one of the Monte Carlo simulation techniques that is suited for our needs. The CONTAMW was chosen to simulate infiltration phenomena in a residential apartment that is typical of residential buildings in Korea. It will be shown that the uncertainty propagating through this process is not negligible and may significantly influence the prediction of the airflow rates.

• Journal of Chest Surgery
• /
• 제41권6호
• /
• pp.724-728
• /
• 2008

배경: 본원에서 자발성 기흉으로 흉강경을 이용 폐 쐐기절제술 후 퇴원한 환자가운데 재발로 수술을 다시 받은 환자에서 기흉의 재발에 관한 위험 인자에 대해 연구하였다. 대상 및 방법: 2002년 1월부터 2005년 12월까지 본원 흉부외과에서 흉강경을 이용하여 흉막 유착술 없이 폐 쐐기절제술만을 시행한 235명을 대상으로 하였다. 퇴원 후 외래 추적관찰 중에 재발이 없었던 A군(225명: 96%), 재발이 있었던 B군(10명: 4%)으로 나누어서 후향적 조사를 통하여 재발 위험인자에 대하여 알고자 하였다. 결과: 각 군의 평균나이는 재발되는 군에서 $19.6{\pm}7.17$세로 더 어렸으며(p<0.05), 각군 남녀 비는 남자가 많았으나, 통계학적 의의는 없었다 흡연력, 병변 부위 및 폐허탈 정도는 양군사이에 유의한 차이는 없었다. 수술적 요인에 대한 것으로 술 후 공기 누출기간이 길수록, 흉관 거치 기간이 짧을수록 재발 가능성이 더 높았으며(p<0.05), 평균 재발기간은 $10.2{\pm}8.5$개월($0.6{\sim}22$개월)이었다. 재발된 군 중 4명은 술 후 한달 동안 충분한 준비 운동 없는 과격한 운동(농구 등)을 했던 경험이었다. 술 후 재발에 영향을 주는 단일 변수는 수술 시 나이,공기 누출기간, 키/몸무게 비 및 흉관 유지 기간이었으며, 다중 변수에 의한 위험 인자는 수술 시 나이, 신장/몸무게 비, 공기 누출 및 흉관 유지 기간 순이었다 결론: 자발성 기흉에서 흉강경을 이용한 폐기포 절제술은 재발율이 개흉술에 비하여 높지 않아서 시행할 수 있지만, 재발 위험인자로 나이가 젊거나, 큰 신장/몸무게비, 지속적인 공기 누출 있거나 짧은 흉관 유지 기간이었으며, 퇴원 후 너무나 빠른 심한 운동은 폐기포절제술 후 기흉 재발의 원인이 될 수 있다.