FFT-FEM을 이용한 자동차용 디스크 브레이크의 열 해석

최지훈,김도형,이인,Choi, Ji-Hoon,Kim, Do-Hyung,Lee, In 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.8

Transient thermal analysis of a three-dimensional axisymmetric automotive disk brake is presented in this paper. Temperature fields are obtained using a hybrid FFT-FEM scheme that combines Fourier transform techniques and finite element method. The use of a fast Fourier transform algorithm can avoid singularity problems and lead to inexpensive computing time. The transformed problem is solved with finite element scheme for each frequency domain. Inverse transforms are then performed for time domain solution. Numerical examples are presented for validation tests. Comparisons with analytical results show very good agreement. Also, a 3-D simulation, based upon an automotive brake disk model is performed.

무인로봇 정밀위치추정을 위한 전술통신 및 영상 기반의 통합항법 성능 분석

최지훈,박용운,송재복,권인소,Choi, Ji-Hoon,Park, Yong-Woon,Song, Jae-Bok,Kweon, In-So 한국군사과학기술학회 2011 한국군사과학기술학회지 Vol.14 No.2

This paper presents a navigation system based on the tactical communication and vision system in outdoor environments which is applied to unmanned robot for perimeter surveillance operations. GPS errors of robot are compensated by the reference station of C2(command and control) vehicle and WiBro(Wireless Broadband) is used for the communication between two systems. In the outdoor environments, GPS signals can be easily blocked due to trees and buildings. In this environments, however, vision system is very efficient because there are many features. With the feature MAP around the operation environments, the robot can estimate the position by the image matching and pose estimation. In the navigation system, thus, operation modes is switched by navigation manager according to some environment conditions. The experimental results show that the unmanned robot can estimate the position very accurately in outdoor environment.

The Relationship between Fat Level and Quality Properties of Ground Pork Patties Cooked by Microwave Energy

최지훈,정종연,최윤상,이의수,김천제,Choi, Ji-Hyun,Jeong, Jong-Youn,Choi, Yun-Sang,Lee, Eui-Soo,Kim, Cheon-Jei Korean Society for Food Science of Animal Resource 2008 한국축산식품학회지 Vol.28 No.3

This study was carried out to elucidate the relationship between different fat levels (0%, 5%, 10%, 15%, 20%, and 25%) and the quality of ground pork patties cooked to reach an internal temperature of $75^{\circ}C$ in a microwave oven. The relationship between fat level and cooking rate of pork patties cooked by microwave energy was highly significant ($R^2=0.72$), and had a low determination coefficient ($R^2=0.55$). The relationship between fat level and total cooking loss of pork patties cooked by microwave energy was also very significant, with a high correlation coefficient of $R^2=0.89$. The correlation coefficient between fat level and cooking drip loss of patties cooked by microwave energy was 0.92, which was highly significant. Although the correlation coefficient between fat level and evaporation loss had a negative value ($R^2=-0.63$), there was a highly significant relationship between fat level and shear force of pork patties cooked by microwave energy.

선체-부가물 영향을 고려한 비공동 수중추진기의 소음예측 연구

최지훈,설한신,박일룡,이수갑,Choi, Jihun,Seol, Hanshin,Park, Ilryong,Lee, Soogab 한국음향학회 2019 韓國音響學會誌 Vol.38 No.3

본 연구에서는 대형화, 고속화되어가는 잠수함 추진기의 소음을 보다 정확하게 예측하기 위하여 선체-부가물-추진기의 상호작용이 묘사되는 유동 수치해석을 토대로 비공동 추진기 소음을 예측하였다. 추진기 방사 소음을 예측하기 위해 선체-부가물-추진기 전체영역에 대한 유동 정보를 전산유체역학 해석으로 얻은 뒤, FW-H(Ffowcs Williams-Hawkings) 음향상사법을 적용하여 두께소음, 하중소음에 대한 소음을 수치적으로 예측하였다. 수치적 소음예측 결과는 모형시험을 통해 검증하였으며, 전체 소음 수준과 저주파 대역 소음예측에 있어 계측결과와 좋은 일치를 보였다. In this study, to predict the noise of a submarine propeller which is going to become bigger and faster, the non - cavitating propeller noise was predicted based on the numerical analysis which considering the interaction of the hull - appendages - propeller. In order to predict the radiated noise of the propeller, the flow field for the entire region of hull-appendages-propeller was computed by CFD (Computational Fluid Dynamics). And the noise for the thickness noise and the load noise was numerically predicted using FW-H (Ffwocs Williams-Hawkings) acoustic analogy. Numerical noise prediction results were verified by model tests and showed good agreement with the measurement results in predicting total noise level and low frequency noise.

Response Evaluation after Stereotactic Ablative Radiotherapy for Lung Cancer

최지훈,Choi, Ji Hoon Korean Society of Medical Physics 2015 의학물리 Vol.26 No.4

정위 방사선치료를 받은 폐암환자에서 결과를 후향적으로 분석하고자 하였다. 연속된 흉부 컴퓨터단층촬영(CT)의 종양의 크기변화 분석을 통해 치료 반응 평가를 조사하였다. 11명의 초기 비소세포폐암환자를 대상으로 정위 방사선치료 선량의 중앙값은 6,000 cGy이고 분할 조사 회수의 중앙값은 5회였다. 경과 관찰기간의 중앙값은 28개월로 치료후 종양의 크기 변화는 총 51회의 CT를 통해 분석하였고, 각 환자당 중앙값 3회의 CT 촬영이 시행되었다. 본 연구에서 치료의 총 반응률은 90.9%로 5명의 환자에서 완전관해와 5명에서 부분관해가 관찰되었다. 부분관해와 완전관해까지의 기간의 중앙 값은 각각 3개월과 5개월이었다. 경과관찰에서 3명의 환자가 병의 진행양상을 나타내었다. 본 연구에서 초기 폐암의 정위방사선치료후 CT 분석을 통해 반응 평가와 함께 치료 반응 시점을 확인할 수 있었다. We retrospectively reviewed lung cancer patients who were treated with stereotactic ablative radiotherapy (SABR). We investigated the value of response evaluation after treatment by measuring the volume change of tumors on serial chest computed tomography (CT) examinations. The study included 11 consecutive patients with early-stage (T1-T2aN0M0) non-small cell lung cancer (NSCLC) who were treated with SABR. The median dose of SABR was 6,000 cGy (range 5,000~6,400) in five fractions. Sequential follow-up was performed with chest CT scans. Median follow-up time was 28 months. Radiologic measurement was performed on 51 CT scans with a median of 3 CT scans per patient. The median time to partial response ($T_{PR}$) was 3 months and median time to complete remission ($T_{CR}$) was 5 months. Overall response rate was 90.9% (10/11). Five patients had complete remission, five had partial response, and one patient developed progressive disease without response. On follow-up, three patients (27.2%) developed progressive disease after treatment. We evaluated the the response after SABR. Our data also showed the timing of response after SABR.

지상파/케이블 데이터방송 재전송 서비스를 위한 PMCP 기반 PSIP 변환기

최지훈,김용호,최진수,홍진우,Choi Ji Hoon,Kim Yong Ho,Choi Jin Soo,Hong Jin Woo 한국정보처리학회 2005 정보처리학회논문지B Vol.12 No.6

본 논문은 디지털방송 서비스의 필수 기술 요소이고 디지털방송 전환과 밀접하게 관련 있는 PSIP 응용 기술인 디지털방송 표준 인터페이스로 표준화된 PMCP(Program Metadata Control Protocol) 인터페이스 규격과, 이를 이용하여 구현된 지상파/케이블 데이터방송 재전송 서비스를 위한 PSIP 변환기의 구조 및 주요 기능에 대해서 기술한다. 본 논문의 PSIP 변환기는 지상파/케이블 데이터방송 재전송 서비스 환경하에서 디지털 지상파 데이터방송 콘텐츠를 디지털 케이블 데이터방송에 재사용하여 데이터방송 콘텐츠 활용도를 높일 뿐만 아니라 실시간 채널 정보 변경 및 방송 프로그램 이벤트 정보 변경만으로 지상파 방송프로그램 안내 정보를 쉽게 재활용/관리할 수 있다. 또한 저장/관리된 방송프로그램 안내 정보를 ATSC T3/Sl에서 표준화한 PMCP 규격을 이용하여 XML형태로 케이블 시스템(OOB SI, Out Of Band Service Information)으로 전송하거나, MPEG-2 전송스트림 형태로 전송할 수도 있다. In this paper, we implemented a terrestrial/cable PSIP converting system, so-called a PSIP converter, which is converting a terrestrial PSIP into a cable PSIP for a data broadcasting service in the interoperable network of terrestrial and cable, and define an interface between the PSIP converter and the OOB SI generator by using PMCP messages compliant to ATSC T3/Sl. The exiting PSIP converter just converts a terrestrial PSIP into a cable PSIP compliant to ATSC and OCAP standard and transmits by a MPEG-2 TS format. That is to say, it is not for the digital data broadcasting but for the digital broadcasting. In addition, the PSIP converter can support various types of PSIP information to the OOB SI generator by using PMCP messages defined by a hierarchical structure as per each channel, audio/video event, data event and so on.

유럽 및 오세아니아의 기능성 축산물과 식육제품에 대한 운영현황 및 관리방안

최지훈,최윤상,김학연,김현욱,김진만,김천제,Choi, Ji-Hun,Choi, Yun-Sang,Kim, Hack-Youn,Kim, Hyun-Wook,Kim, Jin-Man,Kim, Cheon-Jei 한국축산식품학회 2010 한국축산식품학회지 Vol.30 No.5

본 연구는 유럽과 오세아니아의 선진국형 기능성 축산물 및 식육제품의 운영현황 및 관리방안을 연구 분석함으로서 국내 실정에 부합되는 규격기준 표준화와 관리방안 및 제도를 마련하는데 있어서 기초 자료를 제시하는데 있다. 우리나라를 비롯하여 전 세계적으로 국제경쟁력 강화 차원 등의 여러 여건 변화로 식품의 3차적 기능이 점차 강조되고 있다. 따라서 우리나라 자체적으로 기능성 축산물에 대한 정확한 정의와 범위를 확립하는 것이 시급하다. 식품에 기능성 표시를 허용하는 것은 이미 국제적인 대세이다. 유럽과 오세아니아에서도 별도의 기능성 축산물에 관한 법률이나 관리제도가 없으나 식품의 기능성 강화 측면에서 영양표시기준(nutrition claims)과 건강표시기준(health claims)을 통해 식품을 관리하고 있다. 강화 영양소에 대한 표시기준은 일부에 국한되어 있어 이들 기준을 사용하여 국내의 기능성 축산물 및 식육가공품에 적용할 경우, 기능성 지표물질 및 허용량의 설정이 반드시 이루어져야 할 것으로 보이며, EU와 호주 뉴질랜드에서 운영하는 제도 이외의 다른 선진국의 사례를 바탕으로 기능성 축산물에 대한 표준화가 이루어져야 할 것으로 보인다. 또한 기능성 축산물 및 식육제품의 표시를 확립하기 위해서는 현재 시중에 유통되고 있는 제품에 사용되는 기능성 소재 조사 및 각 기능성 소재가 인체에 유해한지 안전성에 대한 연구가 필요하며, 이들 소재의 적정 사용범위 설정을 위한 data base를 확립하기 위해 많은 실험적인 연구가 요구된다. It has recently been considered urgent to establish an accurate definition and scope of functional foods in the livestock industry in Korea. The tertiary function of food is gradually emphasized with various changes in conditions such as international competitive power enhancement of the whole world, including Korea. Therefore, the purpose of this study was carried out to gather basic information toward the establishment of standardization, management plans, and a system adapted to the Korean state through researching management systems of functional meat and meat products in the European Union (EU) and the Oceania Area (OA). A brief summary of this study is as follows. In the EU and OA, special management systems and laws about functional livestock and products were once nonexistent; only 'nutrition claims' and 'health claims' operated in the nutritional consolidation side of foods. Also, it was once thought that functional index materials and permissions established in the application of functional products sufficed, because management standards for enriched food were not established. Therefore, standardization of functional live stock products needs to be considered based on the case of developed countries in the EU and OA. It also seems that the above functional indicative substances can be applied, based on normal standards of indicative substances of functional products and the normal standards of indicators of functional substances added to livestock products presented in this study.

유한요소해석을 통한 복합병렬전단벽 접합부의 성능평가방안에 대한 해석적 연구

최지훈,배백일,최창식 한국구조물진단유지관리학회 2011 한국구조물진단학회 학술발표회논문집 Vol.2011 No.9

The purpose of this study is to find out characteristics for behavior of hybrid coupled shear wall using FEM. Determining optimized length of hybrid coupled shearwalls, a couple of parameters are investigated, compressive strength of concrete, fiber volume fraction, and embedded length. According to analysis result, embedded depth can be designed by shorten length against the ASCE proposed embedded depth. This results suggest that optimization should be needed to design hybrid coupled shearwall eco-nonically.

The Effects of Electric Grill and Microwave Oven Reheating Methods on the Quality Characteristics of Precooked Ground Pork Patties with Different NaCl and Phosphate Levels

최지훈,김학연,안광일,김천제,Choi, Ji-Hun,Jeong, Jong-Youn,Kim, Hack-Youn,An, Kwang-Il,Kim, Cheon-Jei Korean Society for Food Science of Animal Resource 2008 한국축산식품학회지 Vol.28 No.5

The objective of this study was to determine the effects of different reheating methods on the quality characteristics of precooked ground pork patties with different combinations of salt (1, 2%) and phosphate (0, 0.3%). The cooking and reheating methods used were the electric grill and the microwave oven. The cooking method and the addition of phosphate had detectable effects on the quality characteristics of ground pork patties. The reheating rate by microwave oven was faster than by electric grill, and decreased with increases in salt and the addition of phosphate. Cooking loss and reduction in patty diameter after reheating by microwave oven were higher than by electric grill, and these values decreased with increasing of salt/phosphate levels. The pH of patties with added phosphate was significantly higher than patties without phosphate, and no significant difference in pH was observed among patties reheated by each method. The patties reheated by electric grill had higher moisture contents than those reheated by electric grill, and the addition of phosphate resulted in higher moisture contents. The hardness of patties reheated by electric grill was lower than patties reheated by microwave oven, and the addition of phosphate increased the hardness with both reheating methods.

분쇄 계육 가슴살의 도체가공방법과 염지조건이 품질특성에 미치는 영향

최지훈,김일,정종연,이의수,최윤상,김천제,Choi, Ji-Hun,Kim, Il,Jeong, Jong-Youn,Lee, Eui-Soo,Choi, Yun-Sang,Kim, Cheon-Jei 한국축산식품학회 2009 한국축산식품학회지 Vol.29 No.3

This study was carried out to investigate the effect of hot boning and curing condition on the quality characteristics of ground chicken breast. Treatments were cured by four conditions follows; control (general curing method), T1 (after hot-boning and then immediately cured), T2 (after hot-boning and immediately cured, then frozen), and T3 (after hot-boning, immediately frozen, refrigerated and then cured). The pH of chicken breast in the state of pre-rigor was 6.22. The pH of cold storage or freezing chicken breast meat respectively were 5.70 or 5.61. The pH of T1 and T2 treatments were significantly higher than those of control and T3 treatment (p<0.05). After stored for 1 wk, the pH value of T1 treatment had a higher value than those of other treatments. T1 treatment had the highest water holding capacity and the lowest cooking loss among all treatments, regardless of the cooking methods. The reduction in diameter for T1 and T2 treatments was lower than those of control and T3 treatment (p<0.05). T1 treatment had the lowest fat loss and moisture loss among all treatments, and the emulsifying capacity of T1 treatment was the highest. The protein solubility of T1 treatment was significantly lower than that of T3 treatment.