다양한 중합 방법으로 제작한 간접 수복물용 복합레진의 굴곡 강도

김동연,박진영,강후원,김지환,김웅철,Kim, Dong-Yeon,Park, Jin-Young,Kang, Hoo-Won,Kim, Ji-Hwan,Kim, Woong-Chul 대한치과기공학회 2018 대한치과기공학회지 Vol.40 No.2

Purpose: The aim of this study is to evaluate composite resins of indirect restorations for testing of flexural strength according to various polymerization methods. Methods: Specimen was produced a total of 40 to 10 per each group with a length 25 mm, width 2 mm, thickness 2 mm using a Teflon zig. The polymerization groups were classified into four groups. The first group proceeded with light curing only(LC group). The second group proceeded with light and heat curing(LHC group). The third group proceeded with air press and light curing(ALC group). The fourth group proceeded with air press, light and heat curing(ALHC group). Each prepared group was evaluated by flexural strength test. Statistical analysis was performed by one-way ANOVA. Post-test was performed with Tukey test. Results: The lowest in the ALC group was 119.18 MPa and the highest in the ALHC group was 168.15 MPa. There were statistically significant differences. Conclusion : The composite resin of the indirect restoration is recommended to heat curing along with the air press.

와이브로를 통한 모바일 VoIP 서비스의 측정 기반 품질 평가 방안

김동연,김범준,Kim, Dong-Yon,Kim, Beom-Joon 한국전자통신학회 2010 한국전자통신학회 논문지 Vol.5 No.5

Currently the telephone service using Internet grows and the recent introduction of a smart phone is expected to accelerate the trend. In particular, considering the domestic situation that the wireless broadband (WiBro) system deployed over the nation, the telephone service over WiBro can be a solution toward its fast expansion. Unlike telephone service over a conventional telephone network or mobile network, however, internet telephone cannot guarantee it service quality, which can be severer in a wireless environment such as a WiBro network. Therefore, a more strict and systematic management for controlling the quality of internet telephone service over WiBro in a more efficient way. As the first step to establish the management system, this paper proposes a scheme to manage the quality of internet telephone service over WiBro and introduces a software developed for the purpose. The developed software is installed on a user terminal and facilitates efficient service quality management by measuring the quality of internet telephone service over WiBro in terms of VoIP metric, network metric, and wireless metric. 인터넷 전화의 사용이 증가하고 있고 최근에는 스마트폰이 보급됨에 따라서 스마트폰을 통한 인터넷 전화 서비스 이용이 급격하게 증가할 것으로 예상되고 있다. 특히 국내의 경우 이미 전국 상당 지역에 설치된 와이브로를 통한 인터넷 전화 서비스의 제공은 와이브로의 활성화로 이어질 수 있는 좋은 기회라 할 수 있다. 그런데 기존의 전화망이나 이동전화망을 통한 전화 서비스와는 달리 인터넷 전화는 서비스 품질이 보장될 수 없다는 문제점이 있고 특히 무선 환경을 통한 모바일 인터넷 전화 서비스의 경우 이 문제점은 더 심각해 질 수 있다. 따라서 보다 더 엄격하고 체계화된 모바일 인터넷 전화 서비스 품질 관리 방안이 마련될 필요성이 있다. 이를 향한 첫 단계로서 본 논문은 와이브로를 통한 모바일 인터넷 전화 서비스의 품질을 관리하기 위한 방안을 제안하고 이를 구현하기 위하여 개발된 소프트웨어의 개발 과정을 설명한다. 개발된 소프트웨어는 사용자 단말에 장착되어 전체적인 모바일 인터넷 전화 서비스의 품질을 VoIP 품질지표, 네트워크 품질지표, 무선 품질지표로 분류하여 측정함으로써 보다 효율적인 품질 관리가 가능하다는 장점이 있다.

타문화권 환자 진료(방글라데시-1편)

김동연,Kim, Dong-Yeon 연세대학교 의과대학 2005 의학교육논단 Vol.7 No.2

전개성능을 고려한 대형 전개형 SAR 안테나의 회전스프링 힌지의 강성 최적설계

김동연,임재혁,장태성,차원호,이소정,오현웅,김경원,Kim, Dong-Yeon,Lim, Jae Hyuk,Jang, Tae-Seong,Cha, Won Ho,Lee, So-Jeong,Oh, Hyun-Ung,Kim, Kyung-Won 항공우주시스템공학회 2019 항공우주시스템공학회지 Vol.13 No.3

본 연구에서는 전개성능을 고려한 대형 전개형 SAR 안테나의 회전스프링 힌지의 강성 최적설계에 대해 기술한다. 대형 전개형 SAR 안테나는 발사환경에서는 접혀 있다가 궤도에서 임무를 수행할 때 펼치게 된다. 이러한 조건에서 여러 장으로 구성된 안테나 패널을 주어진 시간 내에 최소의 충격으로 전개할 수 있도록 회전스프링 힌지의 적절한 강성을 찾는 것은 매우 중요하다. 회전스프링 강성이 강하면 완전 전개시점에서 발생하는 큰 충격하중이 구조체에 손상을 주며, 약하면 전개 저항으로 인해 완전전개를 보장할 수 없기 때문이다. 이러한 문제를 해결하기 위해서 RecurDyn을 이용한 다물체동역학 해석모델을 생성하였으며 전개해석을 통해 전개성능(전개시간 전개충격하중)을 도출하였다 최적의 회전스프링 강성을 찾기 위해 이에 따른 전개성능을 반응표면법을 통해 근사화 시켰으며 최적설계를 수행하여 적절한 회전스프링의 강성 값을 도출하였다. This paper describes the stiffness optimization of the torsion spring hinge of the large SAR antenna considering the deployment performance. A large SAR antenna is folded in a launch environment and then unfolded when performing a mission in orbit. Under these conditions, it is very important to find the proper stiffness of the torsion spring hinge so that the antenna panels can be deployed with minimal impact in a given time. If the torsion spring stiffness is high, a large impact load at the time of full deployment damages the structure. If it is weak, it cannot guarantee full deployment due to the deployment resistance. A multi-body dynamics analysis model was developed to solve this problem using RecurDyn and the development performance were predicted in terms of: development time, latching force, and torque margin through deployment analysis. In order to find the optimum torsion spring stiffness, the deployment performance was approximated by the response surface method (RSM) and the optimal design was performed to derive the appropriate stiffness value of the rotating springs.

3D 프린팅용 광 중합 수지의 두께에 따른 수축 비교

김동연,김재홍,Kim, Dong-Yeon,Kim, Jae-Hong 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.1

Purpose: To perform a comparative study on curing shrinkage according to the thickness of photopolymerization resin. Methods: Stainless steel molds of 2, 4, and 6 mm heights were prepared. The 2, 4, and 6 mm-height molds were classified as the 2H, 4H, and 6H groups, respectively. A photopolymerization resin was injected into the stainless steel mold. Photopolymerization was carried out using a photopolymer machine. During photopolymerization, the wavelength and intensity of 400~405 nm were set to 10, the highest intensity among 1~10. Photopolymerization was performed for 30 min per specimen (each group=10). The inner and outer areas of the specimen were measured. The data were analyzed using one-way ANOVA and Kruskal-Wallis H test (α=0.05). Results: In terms of the inner and outer diameters of the photopolymerization resin specimen, the 2H group contracted the most, whereas the 6H group contracted the least. A statistically significant difference was found between the groups (p<0.05). Conclusion: The amount of light irradiation of the photopolymerization resin must be adjusted according to the thickness.

DLP 프린터로 출력한 임시의치용 전악 인공치아의 후경화에 따른 변형 분석

김동연,이광영,Kim, Dong-Yeon,Lee, Gwang-Young 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.2

Purpose: This study aimed to analyze deformation according to post-curing of complete arch artificial teeth for temporary dentures printed with a digital light processing (DLP) printer. Methods: An edentulous model was prepared and an occlusal rim was produced. The edentulous model and occlusal rim were scanned using a model scanner. A complete denture was designed using a dental computer-aided design, and the denture base and artificial tooth were separated. Ten complete arch artificial teeth were printed using a 3D printer (DLP). Complete arch artificial teeth was classified into the following three groups: a group no post-curing (NC), a group with 10 minutes post-curing (10M), and a group with 20 minutes post-curing (20M). Specimens were scanned using a model scanner. The scanned data were overlapped with the reference data. Statistical analysis was performed using one-way ANOVA analysis of variance, Kruskal-Wallis test, and Mann-Whitney U test (α=0.05). Results: Regarding the overall deviation of complete arch artificial teeth, the NC group showed the lowest mean deviation of 111.13 ㎛ and the 20M group showed the highest mean deviation of 131.03 ㎛. There were statistically significant differences among the three groups (p<0.05). Conclusion: The complete arch artificial tooth showed deformation due to post-curing. In addition, the largest shrinkage deformation was observed at 10 minutes of post-curing, whereas the least deformation was observed at 20 minutes.

광중합용 DLP 프린터로 제작한 전악 인공치아의 UV-C 초음파 세척에 따른 체적 안정성 평가

김동연,이광영,Kim, Dong-Yeon,Lee, Gwang-Young 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.3

Purpose: The purpose of this study was to compare the dimension safety evaluation between a general ultrasonic cleaner and an ultrasonic cleaner equipped with UV-C (ultraviolet-C). Methods: An edentulous model was prepared. A denture base and an occlusal rim were fabricated, and scanning was performed. After scanning, a denture base and full arch artificial teeth were designed. The full arch artificial teeth were printed using a three-dimensional printer (n=10). The residual resin was washed with alcohol and then scanned (reference data). The printed specimens were classified and cleaned using a general ultrasonic cleaner (GU group) and an ultrasonic cleaner equipped with UV-C (UC group). After each washing, a rescan was performed (scan data). Reference data and scan data were superimposed using overlapping software. Data were statistically analyzed using the Mann-Whitney test (α=0.05). Results: In the deviation values of full arch artificial teeth, the GU group showed a high deviation of 18.02 ㎛ and the UC group showed a low deviation of 15.02 ㎛. The two groups demonstrated a statistically significant difference (p<0.05). Conclusion: Full arch artificial teeth prepared using photopolymerized resin were deformed according to the temperature of water generated in the ultrasonic cleaner. It is judged that there is no deformation according to the UV-C ultrasonic cleaner.

Long-term recombinant interferon-γ treatment in 2 cases of osteopetrosis

김동연,한동균,백희조,정성택,국훈,Kim, Dong-Yun,Han, Dong-Kyun,Baek, Hee-Jo,Jung, Sung-Taek,Kook, Hoon,Hwang, Tai-Ju The Korean Pediatric Society 2007 Clinical and Experimental Pediatrics (CEP) Vol.50 No.11

골화석증은 뼈파괴세포의 기능의 이상과 백혈구의 과산화물 생성 이상을 특징으로 하는 드문 골경화성 질환으로, 유전방법이나 발병나이, 증상, 증상의 정도 등에 따라 몇 가지 아형으로 분류된다. 악성형 골화석증의 궁극적 치료 방법은 조혈모세포이식이지만, 조직형 일치 공여자가 없는 경우나 비교적 양성인 만성형 골화석증에서는 스테로이드나 carcitriol, 인터페론 감마 등의 치료를 시도해 볼 수 있다. 특히 인터페론 감마 치료는 골흡수를 증가시키고, 조혈 기능과 백혈구 기능을 향상시킨다고 보고되고 있다. 본 저자들은 약 6년, 3년 동안 인터페론 감마 치료 후 각각 수혈, 골절과 같은 다른 합병증 없이 조절되고 있는 골화석증 2례에 대해 보고하는 바이다. Osteopetrosis, a rare osteosclerotic bone disease characterized by a defect in osteoclast function and the reduced generation of superoxide by leukocytes, can be classified into several types based on their mode of inheritance, age of onset, severity, and associated clinical symptoms. Stem cell transplantation is the only curative therapy for the infantile malignant type, although alternative treatments, such as corticosteroids, calcitriol, and interferon (IFN)-${\gamma}$ have been attempted in patients with milder clinical types. In addition, IFN-${\gamma}$ therapy has been reported to increase bone resorption and hematopoiesis and to improve leukocyte function. Here, we present the cases of two patients with osteopetrosis who benefited from either 3 or 6 years of INF-${\gamma}$ therapy that resulted in improved blood counts and no further pathological fractures.

디자인 패턴을 적용한 위성영상처리를 위한 군집화 분류시스템의 설계

김동연,김진일,Kim, Dong-Yeon,Kim, Jin-Il 한국정보처리학회 2002 정보처리학회논문지B Vol.9 No.3

본 논문에서는 위성영상을 처리하기 위한 무감독분류 기법인 군집분류 시스템을 설계하고 구현하였다. 구현된 시스템은 새로운 위성영상 포맷과 군집분류 기법의 지원이 용이하고, 확장성 있는 시스템의 설계를 위하여 팩토리 패턴과 전략적 패턴 등 다양한 디자인 패턴을 적용하였다. 군집분류 시스템은 순차군집분류 기법, K-Means 군집분류 기법, ISODATA 기법, Fuzzy C-Means군집분류 기법을 설계, 구현하였으며 Landsat TM 위성영상을 분류기의 입력영상으로 실험하였다. 그 결과 군집분류 기법은 사전지식이 없는 위성영상의 분류를 위한 표본영역의 추출작업과 위성영상의 실시간 분류에 효과적인 사용이 가능함을 보였으며, 재사용성 및 확장성이 우수한 시스템을 개발하였다. In this paper, we have designed and implemented cluttering classification systems- unsupervised classifiers-for the processing of satellite remote sensing images. Implemented systems adopt various design patterns which include a factory pattern and a strategy pattern to support various satellite images'formats and to design compatible systems. The clustering systems consist of sequential clustering, K-Means clustering, ISODATA clustering and Fuzzy C-Means clustering classifiers. The systems are tested by using a Landsat TM satellite image for the classification input. As results, these clustering systems are well designed to extract sample data for the classification of satellite images of which there is no previous knowledge. The systems can be provided with real-time base clustering tools, compatibilities and components' reusabilities as well.

3D 프린팅용 광경화 수지를 사용하여 제작한 의치상용 인공치아의 항온수조 침적에 따른 변형률 비교 분석

김동연,이광영,김재홍,양천승,Kim, Dong-Yeon,Lee, Gwang-Young,Kim, Jae-Hong,Yang, Cheon-Seung 대한치과기공학회 2020 대한치과기공학회지 Vol.42 No.3

Purpose: This study is a comparative analysis of the strain according to deposition in a constant temperature water bath after manufacturing ultraviolet (UV)-cured artificial teeth. Methods: As a control group, 10 ready-made artificial teeth were selected as the first molar on the right side of the maxilla (RT group). Silicone was used as a duplicate of the artificial denture teeth. Experimental teeth were prepared in two groups using the prepared silicone mold. In the first experimental group, the UV-cured resin was injected into the negative silicone, followed by irradiation with a UV-curing machine for 5 minutes (5M group). In the second experimental group, the UV-cured resin was injected into the negative silicone, and then irradiated for 30 minutes using a UV-curing machine (30M group). The one-way ANOVA was performed, and post-test was analyzed by Tukey. Results: When immersed in a water bath for 15 days, it was found to be -0.3% in the RT group, -0.6% in the 5M group, and -0.7% in the 30M group. The results revealed -0.2% in the RT group, 0.2% in the 5M group, and -0.2% in the 30M group when they were in the bath for 30 days. Conclusion: In the water bath, the swelling was greater when deposited for 1 to 15 days, but was less when deposited for 15 to 30 days.