연소 전 고체 추진기관의 내부 온도변화 특성에 관한 실험적 연구

송기혁(Keehyeok Song),강윤구(Yoongoo Kang),구송회(Songhoe Koo) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

고체 추진기관 개발 과정에서 운용조건에서의 성능을 확인하기 위해 일반적으로 저온(-40℃), 상온(20℃), 고온(60℃)의 조건에서 지상연소시험이 수행된다. 온도챔버 내부에서 운용온도 조건으로 조정된 추진기관은 온도챔버 외부에 위치한 시험시설로 이동되고 신속한 설치 후 연소시험에 사용된다. 연소 전 설치과정에서 추진기관은 대기온도에 의해 열손실 혹은 열취득이 발생하게 되며 노출시간이 길어짐에 따라 원하는 시험목표 온도와 상이해질 수 있다. 본 연구에서는 HTPB계 추진제를 사용하는 추진기관을 대상으로 실험을 통해 얻은 내부 온도변화 특성을 제시하였다. Ground combustion test is generally implemented to verify the performance of the motor on the three different operation temperatures(-40, 20, 60℃). The internal temperature of the motor is adjusted to operation temperature by temperature chamber, and the motor is moved out to test facility. After rapid setting, the motor is tested for combustion. In this process, heat loss or heat gain may happen and the long exposure time at outside can cause unintended results. This paper shows internal temperature characteristics of solid propulsion motor using HTPB propellant before combustion.

실내 충격소음에서의 주파수별 귀마개 차음성능에 관한 연구

송기혁(Kee-Hyeok Song),정성학(Sung-Hak Chung) 한국컴퓨터정보학회 2014 한국컴퓨터정보학회 학술발표논문집 Vol.22 No.1

공간크기에 따른 로켓모타 충격소음의 비교분석에 관한 연구

송기혁 ( Kee Hyeok Song ),정성학 ( Sung Hak Chung ),강우람 ( Woo Ram Kang ),이덕주 ( Duk Ju Lee ),박종호 ( Jong Ho Park ) 한국안전학회(구 한국산업안전학회) 2014 한국안전학회지 Vol.29 No.3

The purpose of this study is to analysis the 3 differential size of the interior space for impulse noise. To achieve this goal the 3 kinds (27, 35, 50 m3) of interior space were performed comparing the impulse noise. Result of this study, the standard error of the mean peak sound pressure of value from 0.19 to 0.27dB and there was no significant difference (p<0.01). And B-duration is significant differences (P<0.01) range from 3.98 to 7.93ms. This is respectively less than 10ms. These findings are confirmed in accordance by the 3 differential space size of the indoor-impulse noise due to 0.3 dB or less, so there was no difference to the operational influence. And also below 100 Hz were found fundamental mode frequency analysis. Results were matched with calculated theoretical values.

비구면 렌즈 형상정보 추출을 통한 렌즈 설계 및 성형해석에 관한 연구

송기혁(K. H. Song),홍광표(K. P. Hong),윤호섭(H. S. Yoon),이동원(D. W. Lee),조명우(M. W Cho) 한국소성가공학회 2015 금형가공 심포지엄 Vol.2015 No.8

The development of polishing technology has enabled the production of injection molding with high quality shaping. For products such as mobile phones which require high quality performances the use of plastic materials bring in many restraints such as shrinkage and deflection. The purpose of this research, therefore, is to use reverse engineering in order to find and analyze the data of a prechosen aspherical lens thereby creating a process to design an improved lens. Additionally, the improved lenses are subject to molding analysis. In order to solve this problem lens construction program, Zemax, is used to analyze and optimize performance. In the case of optimization, the object is to eliminate spherical aberration and to find good MTF data. The result of the optimization data was similar to the MTF data found through the random lens. Resin and analysis conditions were selected and CAD modeling was done to enhance the injection molding analysis.

실내 충격소음 측정시스템 구현에 관한 연구

송기혁(Kee-Hyeok Song),정성학(Sung-Hak Chung) 한국컴퓨터정보학회 2014 韓國컴퓨터情報學會論文誌 Vol.19 No.6

본 연구의 목적은170dB 이상의 고충격 소음원에서 실내 충격소음을 측정 평가 할 수 있는 측정시스템 구축 방법을 제안하는데 있다. 이러한 목적을 달성하기 위하여 실내충격소음 측정시스템용 시험장을 설계 및 구현하고, 충격소음 측정용 마이크로폰, Head & Torso Simulator, Ear Simulator를 구성하였다. 충격소음 측정 시 정확한 측정을 위하여 3가지 측정방법을 동시에 측정할 수 있도록 구현하였으며, 정확성과 신뢰성을 위하여 3가지의 실내충격소음 측정값을 상호 비교하였다. 3가지 측정방법에 따른 최대 음압레벨과 옥타브 밴드 결과를 비교 분석함으로써 실내 충격소음의 주파수 특성에 따른 차이점을 확인하였다. 이러한 결과는 반사파의 영향에 의한 것으로 판단된다. 이에, 시험장의 크기를 변형하면서 측정할 수 있도록 실내 충격소음 측정시스템을 구현하였다. 본 시스템 구현을 통하여, 충격 소음원의 특징분석과 해당 주파수별 스펙트럼의 반사파 영향들을 파악할 수 있을 것이며, 향후, 실내 충격소음에 대한 데이터 획득 및 분석을 위하여 유용하게 활용될 수 있을 것으로 판단된다. The objective of this study is to propose the measurement system implementation method for the evaluation and measurement of the indoor-impulsive over 170 dB noise source. For the purpose of measuring impulse noise, design and implementation constructed followed subsystems of the testing center, microphone, ear simulator, head and torso simulator and so on. Measurement systems for the accuracy and reliability of impulse noise are implemented when measuring 3 ways of measurements method by the simultaneous measurement system design. For the accuracy and reliability of three mutually indoor-impulse noise measurements were compared, three kinds of measuring methods in accordance with the peak sound pressure level and octave band. Comparing the results of data, the indoor-impulse noise by analyzing a frequency characteristic was validated in difference for the statistical significance. Result are determined by the influence of the reflected wave. Therefore, the flexible size of the interior test site while interior impulse noise measurement system was constructed. Throughout this system can be affected by parameters that are the impulse noise source and the corresponding frequency-characteristic analysis to determine the spectrum of the reflected wave. And, in the near future, indoor impulse noise measurement systems for acquisition and analysis are utilized in useful data.

휴대용 유도탄의 후방 안전영역 평가방법에 관한 연구

송기혁 ( Kee Hyeok Song ),강우람 ( Woo Ram Kang ),박종호 ( Jong Ho Park ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.2

Recoilless weapons, which lead strong back blast and impulse noise more than 160 dB, have been used in compliance with the regulation of the safety zone for the safe operations. However, the safety zone regulations for the newly developed weapons should be prepared since the existing guidelines do not provide any information concerning the reason for the safety zone. In this study, the outdoor launch tests were performed to collect the data such as noise, pressure and temperature of the back blast. An assessment method using data obtained from launch tests has been proposed to determine the safety zone. The safety zone has been determined with consideration for the following criteria: Impulse noise, temperature and pressure of the back blast and blast angle. As a results, new safety zones for them have been established for the recoilless weapon developed by ADD (Agency for Defense Development). We expect that this research can be used as a guideline for establishing a new safety zone regulation of similar weapon to be developed.

실내에서의 로켓모타 충격소음 특성에 관한 실험적 연구

송기혁(Kee Hyeok Song),강우람(Woo Ram Kang),이덕주(Duck Joo Lee),공병학(Byung Hak Kong),이수갑(Soo Gab Lee),정성수(Sung Soo Jeong),박종호(Jong Ho Park) 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12

본 논문에서는 실내공간에서 발생하는 충격소음의 특성에 대해 연구되었다. 로켓추진장치가 분석을 위한 소음원으로 사용되었으며 동일 성능의 로켓추진기관을 가지고 실외와 실내에서 순차적으로 실험이 진행되었다. 실내실험의 경우 세 가지 실내 공간 크기(27, 35, 50 m3)에서 실험이 수행되었다. 실험 결과에 따르면 실외에 비해 실내에서 최고음압레벨(Peak sound pressure level)과 잔향시간이 크게 증가하였으며 주파수 분석을 통해 100 Hz이하 저주파 영역에서 모드주파수가 발생했음을 확인하였다. 실내공간 크기에 대한 모드주파수 분석 결과에 따르면 실험값이 이론값과 비슷함을 알 수 있었다. In this paper, the characteristics of impulsive sound pressure generated inside the building were studied. The rocket propulsion motors were used as a source of impact sound pressure and sound pressure was measured by using microphones, through launching test to analyze both outdoor and indoor noise characteristics. Indoor launching tests were carried out under three types of indoor size conditions: 27, 35, and 50 m3. According to the indoor launching test results, both peak sound pressure level and reverberation time were highly measured in comparison with the outdoor test cases. The frequencies of the fundamental mode existed in the low-frequency region, below 100 Hz, were found through frequency analysis. These results were well matched with calculated theoretical values.

폭발파 모델을 이용한 실내 음장 해석에 관한 연구

송기혁 ( Kee Hyeok Song ),강우람 ( Woo Ram Kang ),이덕주 ( Duck Joo Lee ),김영남 ( Young Nam Kim ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.4

A portable recoilless guided missile generates a strong back blast and impulsive noise at the nozzle when it launches. In the case of indoor operations, the hazard of the blast noise from a recoilless weapon increases due to limited indoor spaces. Also, the noise levels determine the operational feasibility of a weapon; therefore, it is important to predict the blast noise levels distribution in the indoor space in advance. In addition, computational fluid dynamics (CFD) method generally used for fluid related simulations, requires high computing cost and time to simulate the whole domains. The domain includes both blast wave region and large and various indoor space region. Therefore, an efficient method for predicting the far-field noise level within a short time should be developed. This paper describes an analysis model for predicting the indoor noise distributions by considering the shape effect of the building within a short time. A new developed blast wave model was implemented using the noise source. Additionally, noise reflections at the closed surfaces such as walls and noise transmissions at the opened surfaces such as windows and doors were considered in calculating the noise levels. The predicted noise levels were compared with the experimental data obtained from the indoor launch test to validate the reliability of program.

LED 칩 제조용 사파이어 웨이퍼 절단을 위한 내부 레이저 스크라이빙 가공 특성 분석

송기혁(Song, Ki-Hyeok),조용규(Cho, Yong-Kyu),김병찬(Kim, Byung-Chan),강동성(Kang, Dong-Seong),조명우(Cho, Meyong-Woo),김종수(Kim, Jong-Soo),유병소(Ryu, Byung-So) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.9

스크라이빙 공정은 LED 칩 생성을 위한 절단 공정으로 칩의 특성 및 생산량을 결정하는 중요한 공정이다. 기존의 기계적 방식 및 레이저 방식의 스크라이빙 공정은 칩의 열 변형 및 강도 저하, 절단 영역의 제한 등의 문제점이 있다. 이러한 문제를 해결하기 위해 웨이퍼 내부에 공극을 생성하여 자가 균열을 유도하는 내부 레이저 스크라이빙 공정이 연구되고 있으 나 LED 칩 제작을 위한 사파이어 웨이퍼의 절단에 대한 연구는 미비한 실정이다. 본 논문은 LED 칩 제작에 사용되는 사파이 어 웨이퍼의 내부 레이저 스크라이빙 공정을 적용하기 위해 주요 가공 변수를 정립하고 가공 실험을 통하여 절단 특성을 분석함으로써 내부 레이저 스크라이빙 시스템 구축을 위한 기초 가공 조건을 확립하였다. Scribing is cutting process to determine production amount and characteristic of LED chip. So it is an important process for fabrication of LED chip. Mechanical process and conventional scribing process with laser source has several problems such as thermal deformation, decreasing of material strength and limitation of cutting region. To solve these problems, internal laser scribing process that generates void in wafer and derives self-crack has been researched. However, studies of sapphire wafer cutting by internal laser scribing process for fabrication of LED chip are still insufficient. In this paper, cutting parameters were determined to apply internal laser scribing process for sapphire wafer for fabrication of LED chip. Then, foundation of cutting condition was established to set up internal laser scribing system through investigation of cutting characteristics by several experiments.

CAE를 활용한 Cell Cryopreservation System의 온도 특성 분석

송기혁(K. H. Song),임동욱(D. W. Lim),김지훈(J. H. Kim),하석재(S. J. Ha) 한국생산제조학회 2021 한국생산제조시스템학회 학술발표대회 논문집 Vol.2021 No.12