HL7과 IEEE 1451 기반 센서 네트워크와의 연동에 관한 연구

김우식,임수영,안진수,나지영,김남현,Kim, Woo-Shik,Lim, Su-Young,Ahn, Jin-Soo,Nah, Ji-Young,Kim, Nam-Hyun 대한의용생체공학회 2008 의공학회지 Vol.29 No.6

HL7(Health Level 7) is a standard for exchanging medical and healthcare data among different medical information systems. As the ubiquitous era is coming, in addition to text and imaging information, a new type of data, i.e., streaming sensor data appear. Since the HL7 is not covering the interfaces among the devices that produces sensor data, it is expected that sooner or later the HL7 needs to include the biomedical sensors and sensor networks. The IEEE 1451 is a family of standards that deals with the sensors, transducers including sensors and actuators, and various wired or wireless sensor networks. In this paper, we consider the possibility of interoperability between the IEEE 1451 and HL7. After we propose a format of messages in HL7 to include the IEEE 1451 TEDS, we present some preliminary results that show the possibility of integrating the two standards.

윈도우 함수를 이용한 2차원 신호의 위상복원

김우식,Kim, Woo-Shik 대한전자공학회 1998 電子工學會論文誌, S Vol.s35 No.10

이 논문에서는 윈도우를 이용한 위상복원에 관하여 다룬다, 구하고자 하는 신호의 푸리에 크기와 이 원하는 신호에 서로 보완 (complementary) 윈도우가 곱해진 신호의 푸리에 크기로부터 원하는 신호를 구하는 문제에 대하여 알아본다. 여기서는 유일 조건을 만족하기 위한 여러 조건을 제시하고 Gerchberg-Saxton 알고리즘을 응용한 새로운 복원 알고리즘을 제시한다. 이 연구의 결과는 광학, 특히 천문학에서 Ground-based Telescope의 성능 개선에 이용할 수 있을 것으로 생각된다. In this paper, we consider the problem of reconstructing a two-dimensional signal from its Fourier intensity and the Fourier intensities of two windowed signals: one by a window w(m,n) and the other by its complementary window [1-w(m,n)]. We develop several conditions under which a signal can be uniquely specified to within several trivial ambiguities such as sign, translation,and time-reversal from the given conditions. We present two possible reconstruction algorithms derived from the Gerchberg-Saxton algorithm.

MPEG-4 동영상 압축에서 비트율과 오류 내성을 고려한 인트라 업데이트

김우식,박래홍,Kim, Woo-Shik,Park, Rae-Hong 대한전자공학회 2002 電子工學會論文誌-SP (Signal processing) Vol.39 No.6

동영상 압축에서 움직임 보상은 뛰어난 압축 효율을 보이는 반면에 어느 한 시점에서 오류가 발생할 경우 그 시점 이후로 계속해서 오류가 확산된다는 단점이 있다. 인트라 업데이트 방법은 이러한 오류의 확산을 차단하는 방법이다. 그러나 인트라 업데이트 방법은 압축의 효율을 떨어뜨린다는 단점이 있다. 본 논문에서는 오류의 영향과 비트율 제어를 함께 고려하여 인트라 업데이트를 할 수 있는 방법을 제안한다. 제안된 방법은 비트율과 왜곡의 값을 추정하고 라그랑지안 최적화를 통해 부호화 모드와 양자화 파라메터를 선택하는 방법으로 MPEG-4 코덱에 적용하여 실험하였다. 실험 결과는 제안된 방법이 기존의 방법보다 패킷 손실과 같은 오류 환경에서 더 좋은 화질을 나타내는 것을 보여준다. Motion compensation is a powerful method to compress an image sequence. Its main drawback is that once an error is occurred, the error propagates through the frames. Recently, the intra update method was proposed to stop the error propagation at the expense of reduction in compression efficiency. This paper proposes an intra update method based on a rate-distortion optimization in error prone environments. The rate and the distortion are estimated using the Lagrangian optimization to select the coding mode and the quantization step size. The proposed method is applied to MPEG-4 codec, and the experimental results show that it is robust to the error such as packet losses comparing with the conventional ones.

소듐냉각고속로 원자로 유동분포 시험을 위한 중간열교환기 모의기 설계

김우식(Woo Shik Kim),장석규(Seok-Kyu Chang),어동진(Dong-Jin Euh) 한국유체기계학회 2015 유체기계 연구개발 발표회 논문집 Vol.2015 No.12

화재진압용 스프링클러에 대한 기존 연구 및 동향

김우식 ( Woo Shik Kim ),류성욱 ( Sung Uk Ryu ) 한국액체미립화학회 2008 한국액체미립화학회 학술강연회 논문집 Vol.2008 No.-

하부늑골 골절에 의한 지연성 대량혈흉을 동반한 횡격막 손상

김우식 ( Woo Shik Kim ),김중석 ( Joong Suck Kim ) 대한외상학회 2015 大韓外傷學會誌 Vol.28 No.2

Simple rib fracture is one of most common injury after blunt thoracic trauma found in approximately 7% to 40% of cases. Delayed traumatic diaphragmatic injury with massive hemothorax after rib fracture is rare but a potentially lifethreatening condition. We present a rare case of a 79-year-old male with delayed diaphragmatic injury with massive hemothorax due to fracture of the lower ribs. Under thoracoscopy, hemothorax was evacuated, diaphragmatic rupture was identified and repaired, and the lower ribs were fixed with metal plate (s). Although simple lower rib fractures may be the only clinical finding, close observation and monitoring are required because of the possibility of diaphragmatic and/or intraabdominal organ injury. [ J Trauma Inj 2015; 28: 79-82 ]

미립화 및 분무장치 1 : 다공성 물질 표면의 분무 냉각에 관한 연구 동향

김우식 ( Woo Shik Kim ),이상용 ( Sang Yong Lee ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

Recently, several attempts have been made to enhance the spray cooling performance by employing porous layers or constructing micro-structures on the target substrates. The impinged drops permeate easily through the porous surfaces and the heat transfer area between the solid and the liquid becomes much larger compared to the non-porous case. Also, the duration of the liquid-solid contact becomes much longer due to retention of the liquid within the substrate by the capillary force. At the same time, the pores on the surface behave as the nucleation sites when the substrate temperature is maintained higher than the boiling point. A few studies showed that existence of the optimum geometry of the porous later/structure but any reasonable criterion based on the physical explanations has yet been proposed. To find the ideal spraying conditions and the optimum configuration of the porous layers/structures for improvement of the cooling performance, the heat transfer mechanism of a single-drop impact on the porous surface should be investigated in detail. The amount of liquid mass deposited onto the surface, time of contact and the vapor release rates in single-drop impact should be obtained as fundamental information in estimating the surface cooling performance of sprays. According to the previous studies on hydrodynamic behavior and cooling performance of a liquid drop impinging on a porous substrate, suppression of Leidenfrost phenomenon, decrease in total evaporation time, absence of receding process, and suppression of splash phenomena were observed in accordance with the penetration of the drop into the porous structures. However, most of the previous studies are limited to the qualitative comparison between the porous and non-porous substrates based on each specific type of porous material. Thus, there should be a systematic study on the effects of the porous characteristics (e.g. porosity, permeability) on the post-impingement behavior and the cooling performance. In other words, effects of the nucleation site density and cavity size (represented by the number density of the surface pores and the size of them) on the boiling phenomena (bubble growth rate), and the relationship between the spreading and penetrating behavior (represented by permeability) should be investigated in detail as the future work.

SMART 피동잔열제거계통 성능 해석

김우식(Woo Shik Kim),정서윤(Seo Yoon Jung),문주형(Joo Hyung Moon),이민규(Min Kyu Lee),김영인(Young In Kim),김긍구(Keung Koo Kim) 한국유체기계학회 2015 유체기계 연구개발 발표회 논문집 Vol.2015 No.6

미립화 및 분무장치 : 다공성 표면에 충돌하는 액적 거동에 대한 실험/수치해석적 연구

김우식 ( Woo Shik Kim ),이상용 ( Sang Yong Lee ) 한국액체미립화학회 2013 한국액체미립화학회 학술강연회 논문집 Vol.2013 No.-

Behavior of a water drop impinging on heated porous surfaces was investigated experimentally and then a numerical solver was developed to predict the spreading/penetrating motion. Four porous substrates were prepared by sintering the glass particles with different sizes (60 - 270 μm in diameter). A water droplet was directed to the porous substrates with the initial wall temperature varying from 60ºC to 300ºC. The impinging Weber numbers ranged from 25 to 200 that correspond to the impact velocities from 0.8 m/s to 2.3 m/s for a water drop of 2.6 mm in diameter. The post-impingement behavior was visualized by using a high-speed camera, and the time variation of the surface temperature distribution was measured with the aid of a high-speed IR camera. The post-impingement regime map was constructed based on the observation. Basically three impingement regimes were identified: full-contact regime in the low temperature range and non-contact regime in the high temperature range, and the partial-contact regime between them. The full-contact regime, in which the drop evaporated or boiled while in contact with the surface without any disintegration, was divided into two sub-regimes: internal evaporation and internal boiling. In the partial-contact regime, a vigorous vapor nucleation was observed at the interface between the drop and the surface, which resulted in formation of the secondary droplets. In the non-contact regime, the drop was levitated but at a lower wall temperature with the larger-bead substrates due to more active nucleation on the rougher surfaces. The increase in the Weber number resulted in the higher transition temperature to the non-contact regime. This is considered to be due to the increase of the dynamic pressure at the liquid-solid interface at the instant of impact. Time variation of the surface temperature was also examined. The temperature sharply decreased right after the drop impact, and then increased with time to reach a thermal equilibrium between the penetrated liquid drop and the porous solid structure (phase I). Then the surface temperature decreased again along with the evaporation of the liquid (phase II), and finally increased up to the initial wall temperature upon completion of evaporation (phase III). The total evaporation time decreased with the larger wet-area diameter, which could be achieved with the larger impact velocity. However, there existed an optimum pore size (or size of particles) to show the maximum wet-area diameter and the shortest evaporation time. The spreading diameter and the wet-area diameter turned out to be the major indicators of the cooling performance, which were strongly influenced by both the impact condition and the characteristics of the porous substrates. In order to examine the spreading/penetrating behavior of the impinging drop against porous substrates in detail, a simulation solver (porousInterFoamWoo) was developed. The solver is based on the open source code, OpenFOAM, but the governing equations were modified from those in a pre-adapted VOF solver (porousInterFoam). The effects of the porosity on the displacement of the liquid-vapor interface and the capillary wicking force were additionally considered in the solver. A capillary-rise experiment and a one-dimensional pressure drop measurement were performed to validate the porousInterFoamWoo solver. Finally, the spreading/penetrating behavior of an impinging water drop against the porous substrates was simulated and compared with the experimental data. The solver predicted the time variations of the spreading and the wet-area diameters with a reasonable accuracy. An improved version of the solver that can predict the temperature distribution as well is currently under construction.

핀-관 열교환기용 분배기에서 유량 분배가 압력손실에 미치는 영향에 대한 실험적 연구

김우식(Woo Shik Kim),조성근(Seong Keun Jo),이상용(Sang Yong Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

In the present study, the effect of flow distribution on pressure loss at distributor for fin-tube heat exchanger was investigated experimentally. Filtered tap water was used as working fluid. The working fluid was flowed into single inlet with 10 ㎜ of inner diameter and distributed to seven axisymmetric outlet ports with 2.5 ㎜ of inner diameter. Inlet flow rate range was from 0.06 to 0.09 ㎏/s and flow distribution ratio, which means flow rate through on outlet tube divided by inlet flow rate, was varied from 0.05 to 0.35. Pressure loss at the distributor was estimated from measured pressure profiles in the inlet and one of the outlet tubes. The value of the loss coefficient calculated from pressure loss decreased with the increase of the both inlet flow rate and flow distribution ratio. Empirical correlation of the loss coefficient was proposed in terms of inlet Reynolds number and the flow distribution ratio.