• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 춘계 학술대회논문집
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• pp.41-46
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• 2002

Computational study has been undertaken to investigate the aerodynamic influence of side jet on a supersonic missile and to find a similarity condition between the flight condition and the wind tunnel testing. Tasks were peformed to validate the existing Raytheon test body with side jet, to simulate the flow inside the supersonic wind tunnel, and to compare the flow fields between the missile in free flight and that in the wind tunnel. Then sub-scale model of body-tail configuration was analyzed to estimate the influence of the side jet on the missile components. It is found that the influence of side jet is not as significant on the tail region as on the body surface and a simple algebraic formula for aerodynamic coefficients accounting for the side jet as a point force may be cautiously utilized in setting up control logic.

• 항공우주의학회지
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• 제30권3호
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• pp.91-94
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• 2020

The coronavirus infectious disease-19 (COVID-19) pandemic has had a profound impact on the aviation industry. In order to overcome this crisis, airlines have made their efforts in various fields. Therefore, we tried to summarize these efforts of airlines. It is also essential to keep aircraft that have been in landing for a long time in optimal condition. In this paper, we tried to find out about efforts to maintain landing aircraft and maintenance of personnel. Through such constant care, airlines will be able to quickly respond to increasing aviation demand when the infectious disease situation is stabilized in the future. Finally, airlines and passengers must make several efforts to ensure that passengers are free from COVID-19 while traveling by air. These include general precautions to prevent infection, separation of airline personnel and passengers, changes in seat assignments and in-flight services, periodic aircraft disinfection, and prevention of in-flight infections.

• Mass Spectrometry Letters
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• 제15권1호
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• pp.26-39
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• 2024

Gold nanostructures (Au NSs) are useful and interesting matrices for mass spectrometric analysis of various biomolecules based on organic matrix-free laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF-MS). Au NSs provide high efficiency and versatility in LDI-TOF-MS analysis based on their well-established synthesis and surface functionalization, large surface area, high laser absorption capacity, and photothermal conversion efficiency. Therefore, Au NSs based LDI-TOF-MS can be a facile, functional, and efficient analytical method for important small biomolecules owing to its simple preparation, rapid analysis, salt-tolerance, signal reproducibility, and quantitative analysis. This review chronologically summarizes the important advance of Au NSs-based LDI-TOF-MS platforms in terms of in-depth mechanism, signal enhancement, quantitative analysis, and disease diagnosis.

• 한국축산식품학회지
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• 제44권3호
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• pp.651-661
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• 2024

Chicken broth has a taste of umami, and the stewing time has an important effect on the quality of chicken broth, but there are fewer studies on the control of the stewing time. Based on this, the study was conducted to analyze the effects of different stewing times on the sensory, small molecular metabolites, free fatty acids, and volatile flavor compounds contents in chicken broths by liquid chromatography-quadrupole/time-of-flight mass spectrometry, gas chromatography-mass spectrometry, headspace solid-phase microextraction, and gas chromatography-mass spectrometry. Eighty-nine small molecular metabolites, 15 free fatty acids, and 86 volatile flavor compounds were detected. Palmitic and stearic acids were the more abundant fatty acids, and aldehydes were the main volatile flavor compounds. The study found that chicken broth had the best sensory evaluation, the highest content of taste components, and the richest content of volatile flavor components when the stewing time was 2.5 h. This study investigated the effect of stewing time on the quality of chicken broth to provide scientific and theoretical guidance for developing and utilizing local chicken.

• 한국항공우주학회지
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• 제46권2호
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• pp.95-105
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• 2018

차세대 회전익기 개발에서 고속화는 중요한 과제이며, 선행 연구들을 통해 덕트 팬을 가지는 비행체는 고속화 실현 가능성이 높은 형상으로 평가된다. 본 연구에서는 다중 덕트 팬 비행체의 전진 비행시의 유동 특성 및 공력 성능 분석을 위한 전산해석을 수행하였다. 전방 팬의 공력 성능은 자유류 유동과 팬 유입류에 의해 결정되는 반면, 후방 팬의 성능은 전방 팬에서 발생한 유동에 지배적인 영향을 받음을 확인하였다. 전진 속도가 증가하며 전방 팬 입구에서의 유동 박리는 후방 팬보다 먼저 발생하며, 덕트 입구 박리는 팬 추력의 증가를 유도한다. 두 덕트 팬 간의 상호 작용으로 인해 후방 팬에는 상대적으로 정렬된 유동이 유입되므로 박리 이전까지 추력이 꾸준히 감소하고, 전/후방 팬의 추력의 급격한 변화는 동시에 발생한다. 전진 속도에 따라 전체 비행체의 수직력은 감소하였다. 이는 팬 후류에 의한 동체 아랫면 압력 저하가 주요 원인으로 분석되었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.109-114
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• 2008

This paper presents the development status of a subscale precooled turbojet engine "S-engine" for the hypersonic cruiser and space place. S-engine employs the precooled-cycle using liquid hydrogen as fuel and coolant. It has $23cm{\times}23cm$ of rectangular cross section, 2.6 m of the overall length and about 100 kg of the target weight employing composite materials for a variable-geometry rectangular air-intake and nozzle. The design thrust and specific impulse at sea-level-static(SLS) are 1.2 kN and 2,000 sec respectively. After the system design and component tests, a prototype engine made of metal was manufactured and provided for the system firing test using gaseous hydrogen in March 2007. The core engine performance could be verified in this test. The second firing test using liquid hydrogen was conducted in October 2007. The engine, fuel supplying system and control system for the next flight test were used in this test. We verified the engine start-up sequence, compressor-turbine matching and performance of system and components. A flight test of S-engine is to be conducted by the Balloon-based Operation Vehicle(BOV) at Taiki town in Hokkaido in October 2008. The vehicle is about 5 m in length, 0.55 m in diameter and 500 kg in weight. The vehicle is dropped from an altitude of 40 km by a high-altitude observation balloon. After 40 second free-fall, the vehicle pulls up and S-engine operates for 60 seconds up to Mach 2. High altitude tests of the engine components corresponding to the BOV flight condition are also conducted.

• 한국항공우주학회지
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• 제49권6호
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• pp.497-504
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• 2021

본 논문에서는 항공기가 편대 비행 중에 발생되는 수신잡음에 대한 개선 방안을 연구하였다. 항공기의 통신 장비는 내/외부통신의 기능을 담당하기에 비행 임무 수행과 안전에 있어서 매우 중요하기 때문에 잡음이 없고 깨끗한 통신 품질과 송/수신 기능이 구현이 요구된다. 따라서 수신잡음 현상에 대해서 FTA 분석 및 고장탐구를 수행하였고, 수신잡음에 영향을 주는 인터컴의 내부 잡음 및 송신 끊김 현상이 식별되었다. 인터컴의 다중 접지를 단일 접지로 변경하고 DC Offset 전압을 필터링하는 개선된 방안을 적용하였다. 이를 통해 편대 비행 시 수신잡음 저감을 통하여 항공기 통신 시스템의 품질을 향상시켰으며, 지상 및 비행 시험의 결과로도 확인하였다.

• 한국가시화정보학회지
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• 제15권2호
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• pp.33-40
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• 2017

Abstract In the present study, the characteristics of kinematics and dynamics in the fluttering motion of free-falling plates are investigated at Reynolds number of $10^5$. We record quasi-two-dimensional trajectories of free-falling plates with and without superhydrophobic coating using high-speed camera, and compute the drag and lift forces by trajectory analysis. Translational and angular velocities are modeled as harmonic functions with specific phase differences. In particular, periodic mass elevations near turning points are explained using the suggested models. At each turning point, a sudden drop in lift and a rapid increase in drag occur simultaneously due to fast increase in angle of attack. However, the lift is increased over the buoyancy-corrected weight of plate during gliding flight, resulting in periodic mass elevations near turning points. Superhydrophobicity is shown to increase lift but to reduce drag on a fluttering plate, resulting in the decrease of mean descent speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.821-825
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• 2005

Tilt rotor aircraft was developed for satisfying VSTOL (vertical short take off and landing) capability and cruise performance. However the noise generated by tilt rotor system causes one of the most serious problems. In this paper, noise characteristics of tilt rotor system in hovering flight are predicted by using free wake method and Lowson's formula. The flow field of the tilt rotor is simulated by using time marching free wake method, and the free field acoustic pressure is calculated through Lowson's formula. The predicted results are compared with experimental data at various observing positions. In the near field, they show good agreement with experimental data regardless of rotating speed and collective pitch angles of 6, 8 and 10 degree, although there are some discrepancies between prediction and experiment in the far field and at the rotating axis in the near field. It seems that the reason of these discrepancies is difference of unsteady force fluctuation between experiment and calculation.

• BMB Reports
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• 제53권7호
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• pp.349-356
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• 2020

Mass spectrometry (MS) is an ideal tool for analyzing multiple types of (bio)molecular information simultaneously in complex biological systems. In addition, MS provides structural information on targets, and can easily discriminate between true analytes and background. Therefore, imaging mass spectrometry (IMS) enables not only visualization of tissues to give positional information on targets but also allows for molecular analysis of targets by affording the molecular weights. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS is particularly effective and is generally used for IMS. However, the requirement for an organic matrix raises several limitations that get in the way of accurate and reliable images and hampers imaging of small molecules such as drugs and their metabolites. To overcome these problems, various organic matrix-free LDI IMS systems have been developed, mostly utilizing nanostructured surfaces and inorganic nanoparticles as an alternative to the organic matrix. This minireview highlights and focuses on the progress in organic matrix-free LDI IMS and briefly discusses the use of other IMS techniques such as desorption electrospray ionization, laser ablation electrospray ionization, and secondary ion mass spectrometry.