• 한국정밀공학회지
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• 제29권2호
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• pp.222-228
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• 2012

Haptics and virtual reality are rapidly growing technologies in medical fields. Physicians and nurses can benefit from medical simulation via training and acquire surgical and clinical techniques. In this paper, the research on needle insertion force of biological tissue for haptic based intravenous injection simulator was carried out. We built the setup for needle insertion (intravenous injection) experiments and performed the experiments on live pigs. The force responses against needle insertion were measured using the experimental setup. In addition, the modeling of needle insertion force was carried out with the experimental results and numerical models via nonlinear least-squares method. The results presented in this paper indicate that the developed models can be applied not only to estimate the force feedback during intravenous injection procedure but also to improve the overall training quality of the medical simulator.

• 한국정보과학회논문지:데이타베이스
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• 제31권1호
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• pp.30-38
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• 2004

지구 관측 시스템(EOSDIS)나 많은 수의 클라이언트를 추적하는 이동전화 서비스 등 많은 응용에서는 지속적으로 생겨나는 대량의 복잡한 데이타들을 보관하고 인덱싱하는 것이 매우 어려운 일이다. 다차원 데이타를 효과적으로 관리하기 위해 R-tree에 기반 한 인덱스 구조가 널리 사용되어 왔다. 본 논문에서는 빠른 데이타 생성 속도를 따라잡으면서 대량 삽입을 통해 R-tree를 관리할 수 있는 seeded clustering이라는 확장성 있는 기법을 제안한다. 이 기법에서는 삽입할 대상 R-tree의 상위 k레벨의 구조를 활용하여 시드 트리를 만들어 삽입 데이타를 분류해 클러스터를 생성한다. 그리고 각 클러스터로부터 삽입 R-tree를 생성하고 이를 대상 R-tree에 한 번에 하나씩 삽입한다. 논문에서는 자세한 알고리즘과 함에 다양한 실험 결과를 보여준다. 실험 결과를 통해 seeded clustering을 이용한 대량 삽입이 기존의 대량 삽입 기법들과 비교해 삽입이나 질의 처리 모두에서 우수함을 알 수 있다.

• 한국음향학회지
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• 제22권7호
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• pp.612-621
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• 2003

MP3의 사용이 늘어나면서 저작권 보호나 음악 콘텐츠 정보의 삽입을 위한 방법에 대한 요구가 증가하고 있으며 관련된 연구가 활발히 진행 중에 있다. 이때 부가적인 정보가 삽입되어도 MP3의 비트스트림 구조가 크게 변형되어 음질의 열화나 파일 크기의 변화가 발생하여서는 안 된다. 본 연구에서는 위의 조건을 만족할 수 있도록 MP3 부호화 과정 중에서 양자화 된 정수 형태의 계수가 허프만 부호화 될 때, 값이 큰 샘플들의 특징을 이용하여 linbits 중 몇 개의 비트를 변형하여 부가적인 정보를 삽입하고, 그 음질의 열화 정도를 테스트하였다. 일련의 실험 과정을 통하여 평균 60 bytes/sec의 정보 삽입률에서 MOS 4.6 정도의 음질을 얻을 수 있음을 확인하였다. 제안된 방법을 이용하면 저작권에 대한 정보 또는 미디어 자체에 대한 정보들을 효과적으로 삽입할 수 있어 음악 데이터베이스의 운용과 같은 다양한 분야에 적용될 수 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.148-149
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• 2012

This paper reports doping of carbon atoms in GaN layer, which based on dimethylhydrazine (DMHy) and growth temperature. It is well known that dislocations can act as non-radiative recombination center in light emitting diode (LED). Recently, many researchers have tried to reduce the dislocation density by using various techniques such as lateral epitaxial overgrowth (LEO) [1] and patterned sapphire substrate (PSS) [2], and etc. However, LEO and PSS techniques require additional complicated steps to make masks or patterns on the substrate. Some reports also showed insertion of carbon doped layer may have good effect on crystal quality of GaN layer [3]. Here we report the growth of GaN epitaxial layer by inserting carbon doped GaN layer into GaN epitaxial layer. GaN:C layer growth was performed in metal-organic chemical vapor deposition (MOCVD) reactor, and DMHy was used as a carbon doping source. We elucidated the role of DMHy in various GaN:C growth temperature. When growth temperature of GaN decreases, the concentration of carbon increases. Hence, we also checked the carbon concentration with DMHy depending on growth temperature. Carbon concentration of conventional GaN is $1.15{\times}1016$. Carbon concentration can be achieved up to $4.68{\times}1,018$. GaN epilayer quality measured by XRD rocking curve get better with GaN:C layer insertion. FWHM of (002) was decreased from 245 arcsec to 234 arcsec and FWHM of (102) decreased from 338 arcsec to 302 arcsec. By comparing the quality of GaN:C layer inserted GaN with conventional GaN, we confirmed that GaN:C interlayer can block dislocations.

• Journal of Periodontal and Implant Science
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• 제43권1호
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• pp.30-36
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• 2013

Purpose: Implant stability at the time of surgery is crucial for the long-term success of dental implants. Primary stability is considered of paramount importance to achieve osseointegration. The purpose of the present study was to investigate the correlation between the insertion torque and primary stability of dental implants using artificial bone blocks with different bone densities and compositions to mimic different circumstances that are encountered in routine daily clinical settings. Methods: In order to validate the objectives, various sized holes were made in bone blocks with different bone densities (#10, #20, #30, #40, and #50) using a surgical drill and insertion torque together with implant stability quotient (ISQ) values that were measured using the Osstell Mentor. The experimental groups under evaluation were subdivided into 5 subgroups according to the circumstances. Results: In group 1, the mean insertion torque and ISQ values increased as the density of the bone blocks increased. For group 2, the mean insertion torque values decreased as the final drill size expanded, but this was not the case for the ISQ values. The mean insertion torque values in group 3 increased with the thickness of the cortical bone, and the same was true for the ISQ values. For group 4, the mean insertion torque values increased as the cancellous bone density increased, but the correlation with the ISQ values was weak. Finally, in group 5, the mean insertion torque decreased as the final drill size increased, but the correlation with the ISQ value was weak. Conclusions: Within the limitations of the study, it was concluded that primary stability does not simply depend on the insertion torque, but also on the bone quality.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.115-121
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• 2015

PURPOSE. This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS. The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities ($0.16g/cm^3$, $0.24g/cm^3$, and $0.32g/cm^3$). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at $30^{\circ}$ against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS. The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P<.001). Groups A and group B had similar maximum static compressive strengths, as did groups C and D (P>.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION. The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

• 한국정보통신학회논문지
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• 제13권3호
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• pp.489-497
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• 2009

원 영상을 이용하지 않고 워터마크를 검출할 수 있는 블라인드 워터마킹 기법들은 주로 주파수 변환 계수의 관계를 이용하였다. 하지만 대부분의 블라인드 워터마킹 방법에서는 공격에 취약하고 미세한 계수 값의 변화에도 영향을 많이 받는다. 본 논문에서는 이러한 문제점을 개선하기 위하여 계수 적응적인 다중 삽입 방법과 계수 변경 보호값을 설정하여 공격에 의한 계수 관계 변화를 최소화하였다. 실험 결과 제안한 방법은 우수한 화질에서 손실 압축, 잡음 첨가 등의 공격에 강인함을 유지 할 수 있었다.

• ETRI Journal
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• 제25권2호
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• pp.65-72
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• 2003

To achieve cost and size reductions, we developed a low cost manufacturing technology for RF substrates and a high performance passive process technology for RF integrated passive devices (IPDs). The fabricated substrate is a conventional 6" Si wafer with a 25${\mu}m$ thick $SiO_2$ surface. This substrate showed a very good insertion loss of 0.03 dB/mm at 4 GHz, including the conductive metal loss, with a 50 ${\Omega}$ coplanar transmission line (W=50${\mu}m$, G=20${\mu}m$). Using benzo cyclo butene (BCB) interlayers and a 10 ${\mu}m$ Cu plating process, we made high Q rectangular and circular spiral inductors on Si that had record maximum quality factors of more than 100. The fabricated inductor library showed a maximum quality factor range of 30-120, depending on geometrical parameters and inductance values of 0.35-35 nH. We also fabricated small RF IPDs on a thick oxide Si substrate for use in handheld phone applications, such as antenna switch modules or front end modules, and high-speed wireless LAN applications. The chip sizes of the wafer-level-packaged RF IPDs and wire-bondable RF IPDs were 1.0-1.5$mm^2$ and 0.8-1.0$mm^2$, respectively. They showed very good insertion loss and RF performances. These substrate and passive process technologies will be widely utilized in hand-held RF modules and systems requiring low cost solutions and strict volumetric efficiencies.

• 한국콘텐츠학회논문지
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• 제4권3호
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• pp.61-70
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• 2004

최근 인터넷을 통하여 멀티미디어 데이터와 응용물들이 아주 쉽고 빠르게 분배되며, 전자상거래와 온라인 서비스 등이 급격히 성장하고 있다. 따라서 디지털 데이터에 워터마크를 삽입하여 소유권을 보호하고 데이터의 무결성을 보증하도록 하는 연구가 활발히 진행되고 있다. 본 논문에서는 디지털 이미지를 대상으로 웨이블릿 변환과정을 거쳐 3개의 레벨로 고주파 밴드와 저주파 밴드로 분해하고, 그 후 중주파 밴드에서 시각적으로 중요한 계수를 찾아 인간 시각 시스템(HVS) 기술을 이용하여 눈의 특성에 맞게 워터마크를 삽입함으로써 한층 향상된 화질과 굳건함을 보여 준다. 또한 제안한 워터마킹 알고리즘의 성능평가를 위한 모의실험에서는 워터마크에 대한 여러 가지 공격에서도 삽입된 워터마크가 검출됨을 증명하고 PSNR 값을 구한 복원화질이 우수함을 보여 준다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.468-472
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• 2005

This paper is to investigate the influence of the endface quality on the loss characteristics of a plastic optical fiber connector for in-car network service. Using the parameters of the surface roughness and applied load, insertion loss of connector is measured. Due to scattering and change of refractive index, an optimal condition for low-loss coupling exists. We present the optimal condition as surface roughness $R_{rms}$ = 8 nm and contact load up to 50 N.