주기억장치 DBMS Tachyon을 위한 동시성 제어

김윤호,장연정,김진호,김상욱 강원대학교 정보통신연구소 2000 정보통신논문지 Vol.4 No.-

In this paper, we deal with concurrency control in the Tachyon, a main memory DBMS(MMDBMS). Since an MMDBMS, unlike a disk-based DBMS, performs all of data update or retrieval operations by accessing main memory only, the portion of the cost for concurrency control in the total cost for a data update or retrieval is fairly high. Thus, the development of an efficient concurrency control manager highly accelerates the performance of the entire system. The concurrency control in the Tachyon basically employs 2-phase locking protocol, and has the following characterisics. First, it adapts the partition, an allocation unit of main memory, as a locking granule, and thus, dffectively adjusts the trade-off between the system concurrency and locking cost through the analysis of applications. Second, it enjoys low locking costs by maintaining the lock information dirctly in the partition itself. Third, it provides the latch as a mechanism for physical consistency of system data. Our latch supports both of and Unix semaphore facility. Fourth, for solving the deadlock problem, it periodically examines whether a system is in a deadlock state using lock waiting information. In addition, we discuss various issues arising in development such as mutual exclusion of a transaction table, mutual exclusion of indexes and system catalogs, and realtime application supports.

캠구동기구의 Windup과 Jump해석

김상욱,최연선 成均館大學校 科學技術硏究所 1989 論文集 Vol.40 No.1

Cam driven mechanisms offer a flexibility of design, which is simple, low price and adaptable to high speed. But all cams cause two problems due to eccentricity from shaft-center, the jump phenomenon between cam and follower and the windup of camshaft. The equation of motion for the cam driven system including the shaft windup and the contact, uncontact with follower is drived and solved numerically using 4th-order Runge-Kutta Method. The derived equation of motion shows a self-excited nonlinear vibration. The numerical results shows that three parameters of the follower mass, the slope, and the system stiffness are the most influential design parameters to reduce the vibration at a given speed of operation, and harmonic cam has better performance compared with cycloidal cam.

水泳一스트레스에 의한 血裝 Corticosterone 증가에 미치는 水溫, Clonidine 및 Bromazepam의 영향

金炯健,申炅浩,金庚旭,全普權,千然淑 고려대학교 의과대학 1989 고려대 의대 잡지 Vol.26 No.2

Recently, many reports suggested that warm water swim-stress induces an opioid-analgesia, while cold water swim-stress produces a nonopioid form of analgesia. And Hong et. al. reported that the increase of plasma corticosterone (p-CS) in response to swim-stress at 20℃(20-SS) was significantly attenuated by swim-stress at 4℃ (4-SS) was affected by CL but markedly suppressed by BA. In this paper, the influences of CL-500㎍/㎏ and BA-5㎎/㎏ on the change of p-CS in response to 20-SS or 4-SS were studied in male mice comparing with those of morphine and naloxone. The 20-SS induced increase of p-CS was significantly inhibited by CL and BA, respectively, while the 4-SS induced increase was not affected by CL but markedly inhibited by BA. And the 20-SS or 4-SS induced increase of p-CS was slightly inhibited by naloxone,2mg/kg but not affected by morphine, 2㎎/㎏. The increase of p-SS in response to three times repeated 20-SS or 4-SS with one hour interval was little affected by B-pretreatment, but CL-pretreatment slightly attenuated the 4-SS induced increase of p-CS and significantly inhibited the 20-SS induced increase. The increase of p-CS induced by the repeated SS was little affected by the treatment of BA 30 minutes before the last SS, but the such treatment of CL slightly attenuated the p-CS increase induced by the repeated 20-SS but significantly enhanced the p-CS increase by the repeated the repeated 4-SS. And during the experiment of repeated 4-SS, 55.6% of mice pretreated with BA were drowned. The results demonstrate that there are some pharmacological differences between the mechanisms of hypothalamo-adenohypophysial responses to 20-SS and 4-SS, respectively.

인공신경망을 이용한 전동연삭기의 품질자동검사기 개발

김재욱,최연선 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.1

An automatic quality inspection machine of an electric grinder at its production line is developed using artificial neural network theory. Vibration signal for the quality inspection is measured from a running electric grinder. The vibration signals are analyzed using FFT algorithm for selected five frequency bands, which can specify the cause of faults. The judgement on the quality should have an coincidence between inspector and actual users. In this respect, the judgement criteria were established using artificial neural network theory. A multilayer back-propagation neural network is adopted for training the inspection machine to judge the faults. As a result, judgments using neural network are successfully performed rather than the test by the vibration level only.

Melt spinning 법으로 제조된 Ti-Ni-Cu 합금리본의 상변태거동 및 형상기억특성

金載勳,崔美善,李喜佑,金泰俊,김연욱,南泰鉉 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.7

Phase transformation behavior and shape memory characteristics of Ti-Ni-Cu alloy ribbons fabricated by melt spinning have been investigated by means of differential scanning calorimetry, X-ray diffraction, optical microscopy and thermal cycling tests under constant load. With increasing linear velocity and decreasing ejection pressure, transformation start temperatures of ribbons decreased and stability of the B19 martensite was lowered, comparing to those of alloys fabricated by conventional casting since the cooling rate increased. Only after heat treating ribbons at temperatures higher than 873 K where recrystallization occurred, the B19 martensite was observed in Ti-40Ni-10Cu alloy ribbons. Transformation elongation and hysteresis associated with the B2-B19 transformation in Ti-Ni-Cu alloy ribbons decreased with increasing Cu-content, which was attributed to the decrease in lattice deformations. Transformation elongations of ribbons were larger than those of alloys made by casting, which was closely related to a texture developed in ribbons.

Ti/p-Si 太陽電池의 製作과 特性

羅炳旭,李相潤,孫鍊圭,金東洛 慶北大學校 物理化學硏究所 1984 硏究論文集 Vol.5 No.-

Titanium thin film was deposited on the chemically etched (100) surface of silicon single crystal by the vacuum evaporation. The interfacial oxide was grown by ramp heating. The Ti/p-Si solar cells have shown good rectification properties with the 0.78V built-in potential and the 20㎂/㎠ reverse saturation current density in dark. The best cell have 0.58V open circuit voltage, 38.0 ㎃/㎠ short circuit photocurrent density, 0.64 fill factor and 13.9% energy conversion efficiency under 100㎽/㎠ tungsten halogen lamp irradiation. Therefore, this solar cell is a very promising one, but the life testing is not performed yet in our laboratory.

주기억장치 데이타베이스를 위한 새로운 락 관리

장연정,김상욱,김진호,김윤호 강원대학교 정보통신연구소 1999 정보통신논문지 Vol.3 No.-

The locking is the most widely-used concurrency control mechanism for guaranteeing logical consistency of a database where a number of transactions perform concurrently. In this paper, we propose a new lock management method appropriate for main memory databases. Our method chooses the partition, a fixed-sized container for records, as a unit of locking, and directly keeps lock information within the partition itself. These make our method enjoy the following advantages: (1) it has freedom in controlling of the trade-off between the concurrency and locking overhead by considering the characteristics of given target applications, (2) it enhances overall system performance by eliminating the hashing overhead, a serious problem occurred in the traditional method.

부하순환 하에서 제V급 복합레진 수복물의 미세변연누출에 대한 재접착제의 효과에 관한 연구

윤연희,김영재,김정욱,장기택,이상훈,김종철,한세현 大韓小兒齒科學會 2004 大韓小兒齒科學會誌 Vol.31 No.3

저점도의 레진을 복합레진 수복물 위에 도포하는 것은 미세누출방지와 변연 완전성(integrity) 유지를 위한 한 방법이다. 하지만 장기간 관찰하면, 수복물은 저작압에 의한 영향을 받게 되는데, 저점도의 레진으로 수복물 변연부를 재접착(rebonding)하였을 때 저작압에 의한 응력에 견디면서 계속하여 수복물에 긍정적인 영향을 주는지에 대한 연구는 미흡한 실정이다. 본 연구는 부하순환(load cycling) 하에서 제Ⅴ급 수복물의 미세변연누출에 대한 재접착제 (rebonding agent)의 효과를 알아보고자 하였다. 40개의 건전한 소구치의 협면에 제Ⅴ급 와동을 형성하고 제조사의 지시대로 광중합복합레진으로 수복하였다. 20개씩 무작위로 나누어 표면전색을 하지 않는 Ⅰ군과 표면을 산부식 후 재접착한 Ⅱ군으로 설정하였다. 열순환 후 각 군에서 10개씩의 하위군 (A군=No load cycling군, B군=Load cycling군)으로 나누어 이중 B군의 시편에 1 Hz의 속도로 수직력이 4-100까지 100,000회의 부하순환을 가하였다. methylene blue용액에 침윤시켜 변연의 미세누출릉도를 평가하여 다음과 같은 결과를 얻었다. 1. 교합변연에서는 재접착과 무관하게 유의한 차이가 없었다(ⅠA-ⅡA군, ⅠB-ⅡB군) (p>0.05). 2. 치은변연의 경우는 부하순환을 하지 않은 군의 경우 재접착을 한 군(ⅡA군)이 재접착을 하지 않은 군 (ⅠA군)에 비해 더 적은 미세누출결과를 보였다(p<0.05). 3. 치은 변연에서 부하순환을 시행한 군의 경우에는 재접착을 한 군(ⅡB군)과 재접착을 하지 않은 군 (ⅠB군)과 유의차가 없는 비슷한 미세누출의 결과를 보였다(p>0.05). One clinical technique recommended f3r improving marginal integrity is "rebonding" or application of unfilled resins to the surface of composite restoration. But continuously the restorations are affected with occlusal load. There is room for doubt that the rebonding agent has the positive effect on microleakage in spite of the stress generated by the occlusal load. This study determined the effect of rebonding on microleakage of Class Ⅴ resin composite restorations under load cycling. Class Ⅴ cavities were prepared on the buccal surface of 40 sound extracted premolars and restored with a hybrid light-cured resin composite according to manufacturers' directions. They wert randomly divided into two groups consisting of 20 samples a control(group Ⅰ), without surface sealing, and the other group (group Ⅱ) in which margins were etched and rebonded. After thermocycling, each of groups was divided into subgroups (group A, B), and load cycling(total 100,000 cycles with 4-100N load at a rate of 1 Hz) were applied on the group B. Assessment of microleakage utilized methylene blue dye penetration. The following results were obtained : 1. In the occlusal region, no significant difference was noted in the scores regardless of whether or not the rebonding agent was used (group ⅠA-ⅡA, ⅠB-ⅡB) (p>0.05). 2. In the cervical region, the control group with rebonding (group ⅡA) showed the better result than the group without rebonding (group ⅠA) (p<0.05). 3. In the cervical region, the rebonded group with load cycling(group ⅡB) showed similar results to the groupf·ithout rebonding(group ⅠB) and no significant difference was noted(p>0.05).

HPLC를 이용한 Alnus속 식물에서의 diarylheptanoids의 정량분석

정동욱,김준식,조수민,이연아,김광호,김세원,이민원 중앙대학교 약학연구소 1999 약학 논총 Vol.13 No.-

Quantitative determination of diarylheptanoids (oregonin and hirsutanonol), which were characteristic components of Alnus spp. has been conducted by High Performance Liquid Chromatography. The HPLC analysis was carried out using an YMC J'sphere ODS-H80 column [150×4.6mm, S-4μm. 80A(particle)] and a combination of acetonitrile and H2O was used as mobile phase in gradient solvent system. The results showed differnce in the species (Alnus japonica, A hirsuta and A. hirsuta var. sibirica)

고속 채널환경에 강건한 OFDM 시스템을 위한 채널추정기법

강연석,황태욱,최준철,김영수 경희-다반 ASIC 설계교육센터 2004 경희-다반 ASIC센터 논문집 Vol.5 No.-

본 논문에서는 Orhogonal Frequency Division Multiplexting(OFMB) 시스템의 성능 향상을 위해 파일럿 심볼을 이용한 향상된 채널추정 알고리즘을 제안한다 기존의 LMMSE 알고리즘을 이용한 채널 추정 방법은 파일럿 심볼만을 채널 추정에 이용함으로써 파일럿 간격이 멀어짐에 따라 성능이 현저하게 떨어지는 단점이 있다. 이런 문제를 해결하기 위해 파일럿 사이의 채널을 선 추정하고 이 추정된 값을 다시 파일럿과 함께 이용하여 채널을 추정하는 채널추정기법을 제안하였다. 제안된 추정기법은 도플러 주파수를 36Hz애서 185Hz인 페이딩 채널환경에 적용했다. 기존의 LMMSE 추정기법과 비교했을 때 특히 큰 도플러 주파수애 대해 강건한 특성을 보였다.