• 대한기관식도과학회지
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• 제4권2호
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• pp.188-192
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• 1998

Background and Objectives： The most common cause of the failure of endoscopic dacryocystorhinostomy is closure of the osteotomy site due to granulation or adhesion. We used mitomycin-C, an antineoplastic antibiotic agent, soaking over the osteotomy site to suppress fibrous proliferation and scar formation during the endoscopic dacryocystorhinostomy. Materials and Methods : A total of 20 Patients diagnosed with nasolacrimal duct obstruction were assigned randomly to either a mitomycin-C group or a control group. Endoscopic dacryocystochinostnmy has been used in both groups. In the mitomycin-C group, a piece of merocel soaked with 0.2 mg/ml mitomycin-C was applied to the osteotomy site and then after 30 minutes was removed. Results : All patients in the mitomycin-C group remained symptom free after removal of their silicone tube (100% success), and there were two patients in the control group who had recurrent epiphora (67% success). In the mitomycin-C group, the average surface area of the osteotomy at the end of the sixth postoperative month was 4.1 $\textrm{mm}^2$, whereas that of the control group was 2.5 $\textrm{mm}^2$. Neither serious systemic nor local toxicity were noted in the mitomycin-C group. Conclusion : Intraoperative mitomycin-C may possibly improve success rates over the endoscopic dacryocystorhinostomy procedure.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.226-231
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• 2011

This study set out to review the air current fluidity in exhaust common ducts by installing an inlet pipe at a leisure space in the PS(Pipe Shaft)room for the sake of wind power generation with kitchen and bathroom exhaust common ducts of all the equipment and air conditioning shafts in high-rise apartment. The air current functionality of kitchen and bathroom exhaust common ducts was reviewed by analyzing wind velocity changes according to changes to the area of exhaust common ducts through a simulation, changes to the wind velocity of the kitchen hood by applying an external inlet pipe, changes to the usage factor of exhaust common ducts, and changes to wind velocity by altering the form of the ventilator at the bottom of the old exhaust common duct. It was a basic study on the utilization of exhaust wind velocity in exhaust common ducts.

• 대한기계학회논문집B
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• 제29권3호
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• pp.340-348
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• 2005

Repeated ribs are used on heat exchange surfaces to promote turbulence and enhance convective heat transfer. Applications include fuel rods of gas-cooled nuclear reactors, inside cavities of turbine blades, and internal surfaces pipes used in heat exchangers. Despite the great number of literature papers, only few experimental data concern detailed distributions of friction factors and heat transfer coefficients in square channels varying the number of rough walls. This issue is tackled by investigating effects of different number of ribbed walls on heat transfer and friction characteristics in square channel. The rough wall have a $45{\circ}C$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The heat transfer coefficient and friction factor values increase with increasing the number of rough walls.

• 설비공학논문집
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• 제28권2호
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• pp.75-80
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• 2016

There are three types of dehumidification systems : refrigeration dehumidification method, desiccant dehumidification method and hybrid dehumidification method. The first method involves removing moisture by condensation below the dew point, the second method involves absorption by a desiccant material and the last is an integration method. However, the refrigeration dehumidification system consumes too much power and controlling the humidity ratio is difficult. The desiccant dehumidification system uses less power but it has problems of environmental pollution. The hybrid dehumidification system has the disadvantage of a high initial cost. On the other hand, the energy consumption of the membrane based dehumidification system is lower than for the refrigeration dehumidification system. Also, it is an environmentally friendly technology. In this study, the performance parameters are evaluated for the dehumidification system using a hollow fiber membrane. Available area, duct side dry-bulb temperature, sweep gas flux (flow rate) and LMPD (Log Mean Pressure Difference) were used as the performance parameters.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.379-385
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• 2010

본 연구는 V-gutter형 보염기를 장착한 연소기 내에 발생한 연소 주파수의 발생 메커니즘에 대해 규명하는 것이다. 연소기는 $40{\times}40mm$의 단면적을 가진 긴 덕트 형상을 가지고 있으며, 10,12,14mm의 폭을 가진 V-gutter 형의 보염기를 장착하였다. 연료로 CNG를 수직 분사하여 실험을 수행하였다. 연소시 발생하는 주파수는 연소기의 형상에 기인한 1L 종방향 모드가 발생함을 확인하였다. 또한 보염기의 크기가 화염 가능 영역의 범위에 영향을 미침을 확인하였다. 그리고 종방향 모드의 압력변동이 화염 구조에 중요한 영향을 미침을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.119-123
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• 2013

We conduct the research for reducing aeroacoustic noise occurred when a vehicle operates in high speed situation without modifying the structural configuration such as deforming A-pillar's side curvature. We introduce PAU (Pneumatic Auxiliary Unit) which is a sort of air duct using intake air through radiator grill. According to our research, we can reduce overall noise levels around the surface of HSM (Hyundai Simplified Model). When a vehicleruns 100km/s, area-weighted acoustic power level (AWAPL) indicates 33dB without PAU. However with PAU, coverall AWAPL is decreased to 29dB which means we can improvesilentness approximately 12% compared to ordinary case. Moreover we conduct similar implementation to steering situation especially about yawing. In varioussituations, -10, 0, 10 degree of yawing, we observe 10% reduction in the upstream region of HSM but little increase in downstream region. It seems that inlet air overlap turbulent kinetic energy to surrounding flow. Even though downstream region's noise is louder than upstream region, overall AWAPL is still lower than conventional condition. We also apply this scheme to the real vehicle situation, then we get reasonable output which can support our research outputs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.37-42
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• 2006

In this study, $20Nm^3/hr$ scale compact hydrogen generator which can be apply to the hydrogen station was tested for hydrogen station application. $20Nm^3/hr$ scale compact hydrogen generator was developed by upgrading concept of stacking plate reactor from former $20Nm^3/hr$ scale plate hydrogen generator. concepts for improving system efficiency and performance include such as idea of heat recovery from the exhaust, exhaust duct which is especially design for plate type reactor reinforcement of insulation, enlargement of heat exchange area of reactor, introduction of desulphurizer reactor and PROX rector in a compact design, introduction of back fire protection structure of plate burner and so on, We can learn that final prototype of scale-up $20Nm^3/hr$ scale compact hydrogen generator can be operated steadily in 100% road at which over 94% of methane conversion(S/C=3.75) was obtained. In case of making up the weak point, we expect that it is possible to apply to hydrogen station by way of showing an example.

• 자동차안전학회지
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• 제16권2호
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• pp.44-50
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• 2024

The windshield of a vehicle plays an important role in ensuring driver safety and maintaining visibility. To prevent issues such as frost and mist from occurring inside and outside the vehicle, research related to the defrosting performance of the windshield is being conducted. Evaluating defrosting performance requires accurate thermal flow analyses. Therefore, in this study, a defrosting duct was constructed within a chamber at an actual vehicle scale to evaluate its performance, and a finite element model was developed and verified. To evaluate defrosting performance, the temperature of the windshield was measured under condition with a mass flow rate of 0.1 kg/s, which corresponds to that of a typical midsize vehicle. A total of 45 thermocouples were arranged at equal intervals of 9 widths and 5 lengths on the windshield to measure the temperature and compare it with the temperature predicted through finite element analysis. A volume grid was created in the main flow area to ensure accurate thermal flow analyses, and a prism layer was added at the interface between the windshield and fluid. In total, 6 million grid systems were formed. Comparing the temperature fields of the experimental results and the finite element analysis results confirmed a similar defrosting pattern, with an average temperature difference of 0.64K.

• 대한방사선기술학회지:방사선기술과학
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• 제30권4호
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• pp.357-363
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• 2007

본 연구는 2005년 통계청의 전국 인구비율에 대한 발표를 기준으로 노인 인구 비율이 가장 낮고 광역도시 중 유방암의 조발생률과 연령표준화발생률이 가장 낮은 지역을 중심으로 외래에 내원하여 검사한 유방촬영술과 유방초음파 검사에서 질환별 발생빈도와 검사 분포를 조사하였다. 연중 유방검사 빈도는 7월과 8월에서 가장 많은 검진을 한 것으로 조사되었으며, 연령별 분포는 40대가 39.8%, 30대가 32.4%의 순으로 조사되었다. 외래에 내원하여 검진한 환자 중 질환별 분포는 유방초음파 검사에서 43%가 비정상 소견을 보였다. 그 중 치밀조직과 소결절이 21.5%, 섬유낭종이 8.3%의 순으로 진단 소견을 보였다. 유방촬영술에서는 치밀조직과 소결절이 41.3%, 양성석회화가 6.4%의 순으로 조사되었다. 검사 유형별 조사에서는 유방초음파 검사가 8개 질환으로 세분되어 판독되었고 유방촬영술은 6개 질환에서 진단 소견을 보여 구체적인 질환의 명시가 부족한 것으로 나타났다. 이 지역에서 외래 진료로 유방검사를 실시한 검사자 중 46%가 비정상 소견을 보인 것으로 나타났다.

• 대한핵의학회지
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• 제39권6호
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• pp.489-490
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• 2005

Purpose: The thyroglossal duct runs from the base of the tongue to the thyroid. Rarely the thyroid completely fails to migrate and results in ectopic thyroid tissue, which can be demonstrated scintigraphically. A 31-year old female patient was referred for thyroid scintigraphy due to protruding mass at the base of the tongue. She was mildly hypothyroid. Te-99m pertechnetate thyroid scan was performed to rule out ectopic thyroid gland. There showed a focal area of intense tracer uptake in sublingual area, suggesting the sublingual thyroid. In addition there noted diffusely increased tracer uptake in both breasts. The patient delivered a baby 6 months prior to the scan and was on breast-feeding. Free Tc-99m pertechnetate physiologically secrets into the salivary glands, the stomach, the gastrointestinal tract, the genitourinary tract and the mammary glands and sodium-iodide symporter plays a role in the accumulation of free Tc-99m pertechnetate. We report simultaneous visualization of lactating breasts and ectopic thyroid gland in the base of the tongue.