해외건설 특집 (I) : 해외건설 진출개황 ( Review of Overseas Construction Works )

정재덕 대한건축학회 1978 建築 Vol.22 No.4

우리나라의 해외건설은 1966년 대림산업이 월남에 진출하여 공비 85만불의 항만파일공사를 수주한 것을 효시로 하는데 그 해 대림을 비롯한 6개업체가 동남아 지역에 진출, 합계 1,100만불의 계약고를 올렸다. 그러나 우리나라 해외건설은 1973년 12월 삼환기업이 사우디의 카이바 고속도로공사를 수주함으로써 중동진출을 실현한 후 비로서 본격화 하여 현재에는 국제수지, 고용확대, 경제성장등 모든 면에서 우리나라 국민경제를 선도하는 중요산업으로 성장하였다. 중동지역에 거대한 건설시장이 형성된것은 1973년 석유파동과 유가폭등, 그로 인한 산유국들의 석유수입의 급증에 기인한 것인데 우리나라가 중동지역건설시장에 본격적으로 진출하기 시작한것은 1974년부터이다.

해양플랜트용 허니컴 패널의 차음 특성 연구

정재덕,홍석윤,송지훈,권현웅 해양환경안전학회 2017 海洋環境安全學會誌 Vol.23 No.7

Currently, porous materials (e.g., mineral wool) are the core materials used in offshore plant panels, but in spite of their superb acoustic performance, these items must be replaced for environmental reasons. A honeycomb structure is widely used throughout the industry because of its high strength-to-weight ratio. However, research in terms of noise and vibration is minimal. An acoustic study should be conducted by taking advantage of honeycomb structures to replace porous materials. In this study, a simulation was performed assuming that a honeycomb panel is a superposition of symmetric mode and antisymmetric mode. Reliability was verified by comparing a simulation results based on a theory with a experimental results, and the possibility of the panel as a core material was evaluated by studying the sound insulation characteristics of a honeycomb. As the panel thickness increased, the coincidence frequency shifted to low frequency. As the angle between horizontal line and oblique wall and cell-size decreases, the sound insulation performance is improved. And as the cell-wall thickness increased, the sound insulation performance improved. 현재 해양플랜트용 패널의 주요한 중심재는 다공성재료(미네랄울) 이지만, 뛰어난 차음성능에도 불구하고 환경적인 이유로 이를 대체할 재료가 요구되고 있다. 허니컴 구조는 무게 대비 강도가 우수하여 산업전반에서 많이 쓰이고 있다. 하지만 소음진동 측면에서의 연구는 미미하다. 다공성재료를 대체하기 위한 연구로서 허니컴의 음향학적 연구가 필요하다. 본 논문에서는 허니컴패널을 대칭모드와 비대칭모드의 중첩으로 가정하여 수치해석을 진행하였다. 이러한 이론을 통한 수치해석과 실험결과를 비교하여 수치해석의 신뢰성을 검증하였다. 그리고 수치해석을 통해 허니컴패널의 차음특성을 연구하고 중심재로서의 가능성을 평가하였다. 패널두께를 키울수록 일치주파수가 저주파수로 이동하였다. 셀사이즈와 셀벽의 사이각이 감소함에 따라 차음성능이 개선되었고, 셀벽두께의 경우 증가할수록 차음성능이 향상되었다.

海外建設

鄭在德 대한토목학회 1977 대한토목학회지 Vol.25 No.4

FSI기법을 이용한 수중 센서의 소음차단구조 검증

정재덕,홍석윤,송지훈,권현웅,전재진,서영수 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5

수중센서의 음향성능 및 소음 차단구조 성능 파악을 위하여 여러 가진력에 대해 해석을 수행하였다. 상용 소프트웨어인 ANSYS를 이용하여 수중 몰수체를 내부에서 단위속도로 가진 하였고, 몰수체 외부에서 평면파에 대해 소음 차단구조 성능을 파악하였다. 내부가진에 의한 센서위치에서의 음압차단률은 다소 변동이 있었지만 평균적으로 주파수가 높아질수록 음압차단률이 낮아지는 경향을 보였고, 구조진동 차단률의 경우는 주파수가 올라감에 따라 전체적으로 높아졌다. 평면파의 경우 주파수 별로 음압의 차이뿐만 아니라 정상상태에 도달하기전에 소폭 음압이 상승함을 보였다. 이를 위하여 구조와 유체를 연성해석하는 FSI(fluid structure interaction)기법을 이용하여 검증하였다.

치과 Implant 보철 수복시 자연지대치와의 연결형태에 따른 응력분석의 유한요소법적 분석

鄭載悳,曺仁鎬 단국대학교 치의학연구소 1992 논문집 Vol.4 No.-

Dental prosthodontics, of which primary objective is the rehabilitation of mastication, esthetice and phonetics etc. caused by the loss of teeth and their supporting structures, has a new vista in which the studies of making fixed or removable prosthesis by implanting artificial roots into jaw one are actively under progress. In the early phase, osseo-integrated implants were mostly used for the treatment of fully edentulous patients byt recently various methods of rehabilitation partial edentulous jaws has been studied and are actually applied to the clinical use. Clinicians have much interest in the connection modalities of the natural abutments and implants, and he fact which type of connection brings about the most favorable results is a very important question. As a part of biomechanical study of biofunction, stress analysis using finite elements were applied to compare and analyse stress produced in adjacent bone tissue to the natural abutments and dental implants. Experimental models have dental implants in partial edentulous areas in the lower arch, where 1st and 2nd molars were unilaterally lost. 4 finite models(free standing, rigid, semi-rigid, and telescopic connector) were designed. Load of 1.5Kg and 30Kg were applied to each experimental group respectively. After the models were checked and results were calculated by the transformation procedures following results were obtained. The stress occuring along the interface of cortical bone and supporting structures of the abutments, and along the cancellous bone, were compared according to the model types. 1. In the free standing implant prosthesis, which is not connected to the natural abutment tooth, high stress distributions were observed in the distal third area of natural abutment apex, mesio-cervical area of 1st implant and in disto-cervical area of 2nd implant in all of experimental groups. 2. In the case of rigid and telescopic models of 3 unit bridge, using one natural abutment and one implant fixture, stress distribution and amount were similar in both group 1(1.5㎏) and group 2(30㎏). High stress distributions were observed in the mesio-apical third of natural abutment and cervical region of implant fixture. 3. In the semi-rigid model, high stress distributions were observed in the cervical region of natural abutment and cervical third of implant fixture in group 1.Stresses were more concentrated in implant fixtures. In group 2, high stress distributions were observed in the apical third of natural tooth and in the mesio-apical third and disto-middle third of implant fixtures. The stress was concentrated more from mesio-apical third to the disto-middle third in the implant fixture than natural abutment tooth. 4. In the cancellous bone under the interface of cortical bone, natural abutment and implant fixtrue, stresses were concentrated on underlyingapex of natural abutment tooth in free standing model. Stree distribution was high in disto-middle third of natural abutment in rigid and telescopic model, and it was relatively high in each underlying apex of natural abutment. In group 1 of semi-rigid model, high stress distributions were observed in the disto-middle third of abutment tooth and in the mesial surface of implant fixtures. Stress distributions were high in the disto-middle third natural abutment and mesial and apical region of implant fixtures in group 2. 5. Under the limits of elasticity, the pattern of stress distribution was almost unaffected by the differences in the load applied, but resultant stress amounts were affected by the magnitude in the forces applied.

FSI기법을 이용한 수중 센서의 소음차단구조 검증

정재덕,홍석윤,송지훈,권현웅,전재진,서영수 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5

수중센서의 음향성능 및 소음 치단구조 성능 파악을 위하여 여러 가진력에 대해 해석을 수행하였다. 상용 소프트웨어인 ANSYS롤 이용하여 수중 몰수체를 내부에서 단위속도로 가진 하였고, 몰수체 외부에서 평면파에 대해 소음 차단구조 성능을 파악하였다. 내부가진에 의 한 센서위치에서의 음압치단률은 다소 변동이 있었지만 평균적으로 주파수가 높아질수록 음압차단를이 낮아지는 경향을 보였고, 구조진동 차단률의 경우는 주파수가 올라감에 따라 전체적으로 높아졌다. 평면파의 경우 주파수 별로 음압의 차이뿐만 아니라 정상상태에 도달하기 전에 소폭 음압이 상승함을 보였다. 이를 위하여 구조와 유체를 연성해석하는 FSI(fluid structure interaction)기법을 이용하여 검증하였다.

폴리에스테르 織物에 대한 減量加工이 “태”의 特性變化에 미치는 影響

鄭在德,鄭濟石,朱鋼 단국대학교 대학원 1985 學術論叢 Vol.9 No.-

Characteristics variances of domestic polyester fabrics are Conducted by treating with different concentrations of alkaline solution and temperature. Consequently, the effects to the handle of polyester fabrics are studied as follows: 1) Weight decreasing phenomena appeared as a line equation when treated in 7.5∼15.0 percentage of alkaline concentration, and 60∼90 degree centigrate of treating temperature. 2) Atong with decreasing weight, softness and smoothness of polyester fabrics are increased but fullness and tightness are decreased. 3) In relation with sensory properties and physical properties, softness and smoothness are revealed as a mines correlat ionship, and fullness and tightness plus correlationship. are revealed 4) The regression equations sensory characteristics related with physical ones are calculated as follows: softness: y=44.098-0.136x smoothness: y=44.594-0.140x fullness: y=6.399+0.140x tightness: y=5.969+0.145x

Development of eco-friendly and lightweight insulation panels for offshore plant

정재덕,홍석윤,송지훈,권현웅,주원호,김성훈 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.6

Recently, regulations pertaining to the noise and vibration environment of offshore plants have been strengthened. For example, the NORSOK standards have been applied, which are very strict regulations that are comparable to those applied to passenger ships. Furthermore, the use of porous materials, such as those used in most of the current insulating panels, has been forbidden. Therefore, honeycomb-backed Micro-Perforated Plates (MPPs) are now regarded as next-generation absorber materials. This paper reports the results of parametric studies that were performed using numerical methods to determine the effect of the thickness on the performance of a honeycomb panel and the effect of the perforation ratio on the MPP performance. The numerical results were verified through experiments. Finally, we propose a combined honeycomb/MPP panel where the MPP is placed between upper and lower honeycomb panels and one end surface is also replaced with an MPP.

용기와 협동을 심어 자랑스러운 양계인이 되자

정재덕 대한양계협회 1979 월간 양계 Vol.11 No.11

미세 천공판이 적용된 허니컴패널의 차음성능 연구

정재덕(Jae-Deok Jung),홍석윤(Suk-Yoon Hong),송지훈(Jee-Hun Song),권현웅(Hyun-Wung Kwon) 한국소음진동공학회 2018 한국소음진동공학회 학술대회논문집 Vol.2018 No.10