• 대한의생명과학회지
• /
• 제11권3호
• /
• pp.407-416
• /
• 2005

Cardiopulmonary bypass (CPB) for cardiac surgery induces the production and release of numerous chemotactic substances and cytokines, ensuing systemic inflammatory response that causes postoperative major organ dysfunctions. We performed a randomized, prospective study to investigate clinical effects of preoperative treated-methylprednisolone for preventing inflammation in pediatric cardiac surgery with CPB. Thirty pediatric patients scheduled for elective cardiac surgery were randomized to either control(n=15) or steroid group (n=15, 10 mg/kg of methylprednisolone). Arterial blood samples were taken before and after the operations for measuring total leukocyte (T-WBC) and differential counts, platelet counts, interleukin-6 (IL-6), myeloperoxidase (MPO), neuron specific enolase (NSE), troponin-I (TNI), aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine levels. Postoperative parameters such as pulmonary index (PI, $PaO_2/FiO_2$), 24 hrs and total bleeding volumes, mechanical ventilating (MVP) and intensive care unit (ICU)-staying periods, and hospitalization were assessed. T-WBC, neutrophil fraction, IL-6, MPO, NSE, TNI, AST and creatinine levels, bleeding volumes, PI, and MVP at the postoperative periods were lower or shorter in steroid group than in control group (P<0.05). These findings indicated that preoperative administration of methylprednisolone attenuated CPB-induced inflammatory reactions, contributing to postoperative recovery of patients underwent cardiac surgery.

• 대한기계학회논문집B
• /
• 제23권6호
• /
• pp.695-702
• /
• 1999

A cross-flow fan which constitutes a fan-duct system with a stabilizer and a scroll-casing is widely used in many air-ventilating and air-conditioning devices. The cross-flow fan system has many design parameters which have crucial influence on the performance and the noise characteristics of the devices, which means many difficulties during the design stage of the devices and the general design guide has not sufficiently established yet. This study presents the experimental results of the parameter investigation of some chosen design parameter values, which are the shapes of the stabilizers, the profiles of the scroll casing part, and the diffusion angles of the flow exit. The results are expressed by the varying performance characteristics with the values of the parameters. They are found to have considerable effects on the system performance and should be considered with care in the design stage. Finally some helpful guides for the design and manufacturing of the cross-flow fan system are proposed.

• 한국생활과학회지
• /
• 제18권2호
• /
• pp.509-522
• /
• 2009

This is a basic study to improve air quality of school classrooms in winter time. The purposes are to check indoor thermal and air environment in school classrooms during winter and to analyze influencing factors on indoor environment. The measurements of students' physical elements with questionnaire surveys were carried out in a total of 6 classrooms. As a result, this research shows that the temperature of one classroom was below indoor thermal standard level, three classrooms had lack of heat, and two classrooms are heated much, which induce relatively low humidity. All of 6 classrooms had lack of ventilation, being high level of $CO_2$ concentration and 2 classrooms are in condition of high PM10 concentration. The majority of students(76%) answered that the cause of their 'heated space syndrome' is because of the lack of ventilation. Students' opening windows for ventilations is hardly carried out at normal times, except that indoor temperature is over standard. That is, we can suggest one of solutions, which is to enable students to operate heating and ventilating system by themselves according to students' physical condition.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 춘계학술대회 논문집
• /
• pp.588-593
• /
• 2011

The Main design parameters of ship HVAC systems are pressure drop and noise analysis of ducts. The Noise prediction for HVAC(Heating, Ventilating and Air Conditioning) systems are normally performed by empirical method suggested by NEBB(National Environmental Balancing Bureau, 1994), but NEBB's method is not suitable for the ship HVAC systems. In this paper, numerical analysis methods are used to develop a noise prediction method for the ship HVAC systems, especially for large ducts. To develop regression formula of attenuation of sound pressure level in large duct, Boundary Element Method(BEM) is used. Using dynamic loss coefficient which is suggested by ASHRAE fitting data base and numerical methods of HVAC noise analysis, integrated HVAC noise analysis of Program is developed. The developed program can present pressure drop and noise analysis of the ship HVAC systems. To verify the accuracy and convenience of the developed program, prediction of HVAC system for Semi-Submersible Drilling RIG is carried out and the results are compared with measurement of noise level during sea trial.

• 한국화재소방학회논문지
• /
• 제17권3호
• /
• pp.50-54
• /
• 2003

본 연구는 도로 터널 화재 발생 시 연소가스의 backlayer현상을 수치실험하고 그 결과를 분석하였다. 상업용 열 유체해석코드인 PHOENICS를 사용하여 정상상태의 열 유동현상을 수치해석하였으며 환기용 공기속도를 독립변수로 하고 종속변수는 backlayer의 길이로 하였다. 수치해석에 사용한 난류모델은 $textsc{k}-\varepsilon$ 모델을 사용하였고 Hybrid 차분법을 사용하고 질량 잔류값을 수렴조건으로 사용하였다. 수치실험 결과 backlayer의 길이가 환기 속도에 반비례하여 감소하고 backlayer가 발생하지 않는 임계 환기속도가 있음을 확인 할 수 있었다. 또한 연소가스의 수직방향 성층화로 터널하부에 승객이 대피할 수 있는 공간이 존재함을 확인 할 수 있었다.

• 대한기관식도과학회:학술대회논문집
• /
• 대한기관식도과학회 1987년도 제21차 학술대회 연제순서 및 초록
• /
• pp.20.3-21
• /
• 1987

저자들은 1977년 10월부터 1987년 3월까지 한양대학교 부속병원 이비인후과에서 경험한 기도 이물환자 20명을 대상으로 임상적 관찰 후 다음과 같은 결과를 얻었다. 1) 성별은 남자 16예(80%) 여자 4예(20%)로 남자에서 4:1의 비율로 많았고, 연령별은 4세이하가 16예로써 80%를 차지하였다. 2) 발병후 내원까지의 기간은 24시간이내가 12예(60%), 2-3일이 3예(15%), 그 이후가 5예(25%)이었다. 3) 개재부위로는 좌측 기관지 10예(50%)로 가장 많았으며, 우측 기관지 6예(30%), 기관 2예 (lo%) 순이었다. 4) 이물의 종류는 식물성 9예(45%)로 가장 많았으며 그 외에 플라스틱 5예(25%), 금속성 3예(15%), 골편이 1예(5%), 미발견이 2예(10%)순이었다. 5) 내원 당시 주증상으로는 기침 10예(50%), 호흡곤란 6예(30%), 청색증 4예(20%), 무증상 3예(15%), 전흉부동통 1예(5%)순이었다. 6) 초진시 이학적 소견으로는 호흡음감소 14예(70%)가 가장 중요한 소견이었으며 수포음 5예(25%), 흡기성 천명 3예(15%), 흉벽함몰 3예(15%), 특기소견 없는 경우 3예(15%)순이었다. 7) 흉부 X-선 소견으로는 무기폐 8예(40%), 무소견 6예(30%), 폐기종 4예(20%), 이물음영 3예(15%), 폐렴소견 2예(10%)순이었다. 8) 적출은 ventilating bronchoscope를 이용하였다.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2005년도 동계학술발표대회 논문집
• /
• pp.33-38
• /
• 2005

A hybrid ventilation system was introduced to predict the ventilation performance of the apartments. This ventilation system was composed of the natural supply-air inlet and the forced exhaust-air outlet. Analysis was conducted by CFD technique and was performed on three ventilating flow rates; 30, 60, 120 $m^3/h$. As the results, residents feel comfortable thermally and in air flow conditions for 60 $m^3/h$. But the case of 30 $m^3/h$ shows 1100ppm of $CO_2$ concentration due to the deficient of air flow rate. In the case of 120 $m^3/h$, however, residents feel uncomfortable thermally and in air currents. In this study the energy saving for space heating is also an important factor. A detailed prediction for more complicated whole apartment space will be investigated in the future.

• 설비공학논문집
• /
• 제29권1호
• /
• pp.1-6
• /
• 2017

In order to better save energy, many buildings have been constructed with high levels of insulation and airtightness in recent years. Additionally, having high quality indoor air has become more relevant, necessitating a ventilating system. This study is aimed at evaluating the performance of a humidity exchanger through computational fluid dynamics (CFD) analysis of elements for the purpose of providing comfortable indoor air and reduced energy consumption. The simulation was conducted with three different shapes (triangle, rectangular, and curve) of heat exchanger elements, in order to find the most effective element. A follow-up simulation then proved the efficiency of the chosen humidity exchanger, which was selected by analyzing the results of the preceding simulation, comparing study data with measurement data from the Korea Testing Laboratory (KTL). The resulting analysis revealed that the rectangular element showed the lowest level of efficiency in both heating and cooling, while the curved element showed the highest level of efficiency in both heating and cooling.

• 한국지능시스템학회논문지
• /
• 제18권1호
• /
• pp.60-65
• /
• 2008

본 논문에서는 강인 디지털 제어기를 통한 스마트 스페이스의 안정도에 대해 논의하고자 한다. 제안된 제어기 설계 방법은 지능형 디지털 재 설계 기법을 적용하는 것이다. 좀 더 구체적으로, 불확실성 및 비선형성이 포함된 아날로그 시스템을 Takagi-Sugeno 퍼지 모델을 사용하여 나타낸다. 그리고 전역적 지능형 디지털 재 설계를 위하여 해당 문제를 볼록 최적화 관점으로 변환 한 후, 에러가 가질 수 있는 놈의 영역을 최소화하여 상태 정합을 이루고자 하였다. 전역적 접근을 통해 정리된 식은 선형 행렬 부등식으로 나타나게 된다. 마지막으로, 설계된 제어기를 HVAC (Heating, ventilating, and air conditioning) 시스템에 적용함으로써 효율성을 입증하고자 한다.

• 한국기계가공학회지
• /
• 제13권4호
• /
• pp.106-112
• /
• 2014

This study presents the mechanical behavior of a ventilating window (a tsunami damper) on the building wall of a nuclear power plant. The window, which is under development, is used to ventilate a machinery room and the building under normal conditions, but it also provides a safety barrier for critical equipment against a tsunami caused by an earthquake. A finite element analysis was conducted to investigate the deflection and the stress distribution of the window under given loading conditions. With symmetry, a one-quarter portion of one window was modeled, and the pressure due to a great tide is assumed to be 7 bar. A structural analysis of the assembled frame, composed of a blade and casing, was also conducted using contact conditions to find the stress and strain configurations caused by the applied pressure.