• 대한관절경학회:학술대회논문집
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• 2009.10a
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• pp.14-22
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• 2009

회전근 개 부분 파열은 노화의 과정 중 생기는 무증상의 병변 또는 견관절 기능 장애의 잠재적인 원인으로 생각되었다. 발병 원인은 해부학적인 원인에 의한 충돌 또는 반복적 미세 외상 등이 원인으로 이해되고 있으며 병리생태에 관한 이해가 깊어지고 진단 기구, 즉 초음파나 자기공명영상, 관절경 등의 발달로 발생률이 과거에 비해 증가하고 있다. 그러나 회전근 개부분 파열은 질환 자체보다 전층 파열로 진행하는 일종의 질환 스펙트럼(disease spectrum)의 개념으로 전층 파열에 비해 현재까지 발표된 연구 자료가 많지 않다. 즉 회전근 개 부종, 견봉과의 마찰로 생긴 염증성 건병증, 회전근 개 섬유화 및 부분 또는 전층 파열로 진행되는 회전근 개 병변의 스펙트럼의 일부로 간주되는 경우가 많다. 본 종설은 회전근 개 부분 파열의 진단, 파열 분류, 수술의 적응증 및 수술 방법과 그 결과에 대해 논하고자 한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.62-76
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• 1995

The safety analysis becomes very essential in the crash environment with the growth of automobile industry. Recently, an airbag system is required to protect the occupant. The effects of an airbag can be evaluated exactly from the barrier or sled test which is quite expensive. The airbag system in a passenger car is analyzed with the occupant analysis program. The modeling of the passenger car including an airbag is established and the results are verified by comparisons with real crash tests. However, the solution of an airbag design can not be obtained easily with the conventional method such as an optimization due to the nonlinearity and complexity of the problem. An iterative design algorithm using the orthogonal array is proposed to overcome the difficulties. The design trend of an airbag is recommended to minimize the injury of an occupant with the proposed design algorithm and the results are discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9A
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• pp.1601-1608
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• 2001

본 논문에서는 무선 ATM 환경에서 음성과 같은 실시간 서비스가 요구되는 트래픽의 QoS를 보장하기 위한 구현 방법을 제안하였다. 음성은 셀이 발생되는 토크스퍼트 구간과 셀이 발생되지 않는 휴지구간이 주기적으로 반복되는 특성을 갖는다. 따라서 음성과 같은 실시간 서비스의 QoS를 보장하기 위해서는 휴지구간 상태에 있는 음성단말의 수와 음성단말의 상태를 고려하여 음성단말의 수에 관계없이 일정한 QoS를 보장할 수 있어야 한다. 음성단말의 수에 관계없이 일정한 연결 지연시간을 제공하기 위하여, 휴지 상태에 있는 음성 단말 수와 휴지 상태의 지속시간에 따라서 동적으로 음성 예약 슬롯을 할당하는 방식을 제안한다. 컴퓨터 시뮬레이션을 통하여 slotted-ALOHA나 NC-PRMA 같은 기존의 슬롯 할당방법과 비교하였으며, 그 결과 제안된 방법이 동적으로 예약슬롯을 할당하여 부하에 관계없이 음성 트래픽에 일정한 지연시간과 낮은 충돌율을 제공하면서 프레임에 예약슬롯의 오버헤드를 최소화하므로, 채널 사용 효율을 높일 수 있음을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.41-48
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• 2006

An anti-collision algorithm is very important in the RFID system because it decides tag identification time and tag identification accuracy. We propose improved anti-collision algorithms using Bin slot in RFID system. In the proposed algorithms, if the reader memorizes the Bin slot information, it can reduce the repetition of unnecessary PingID command and the time to identify tags. If we also use ScrollA11ID command in the proposed algorithm, the reader knows the sequence of collided E bits. Using this sequence, the reader can reduce the repetition of PingID command and tag identification time. We analyze the performance of the proposed anti-collision algorithms and compare the performance of the proposed algorithms with that of the conventional algorithm. We also validate analytic results using simulation. According to the analysis, for the random tag n, comparing the proposed algorithms with the conventional algorithm, the performance of the proposed algorithms is about $130\%$ higher when the number of the tags is 200. And for the sequential tag ID, the performance of the conventional algorithm decreases. On the contrary, the performance of the proposed algerian using ScrollA11ID command is about $16\%$ higher than the case of using random tag ID.

• Journal of Advanced Navigation Technology
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• v.12 no.4
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• pp.357-365
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• 2008

Broadcast is a efficient interactive method between a server and mobile clients via wireless channel and broadcast environments are incarnating as various applications. Most studies have been proposed in broadcast environments deal with read-only mobile transactions, many applications are emerging recently that need to manage the update transactions at mobile clients. So we propose a concurrency control for mobile transactions consisted mainly of update operations in broadcast environments. As an optimistic approach is applied for scheduling update transactions, repetitive aborts of update transactions are occur due to conflict between transactions. To solve this problem update transactions must have been executed with distributed manner, but unnecessary aborts are occur as well because of continuous restart. Thus, in this paper we propose a method that transactions are executed distributed manner and can avoid unnecessary aborts of update transactions. Proposed method has no unnecessary uplink and can save resources of mobile client.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.3
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• pp.825-831
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• 1996

Using the two-dimensional hydrocode HI-DYNA2D, a calculation on the explosive selding of dissimilar plates(Steel Titanium) was made for the pressure, temperature, velocity and impact ingles adjacent to the collision point during the welding process. The FEM result indicates that optimal stand-off distance of initially parallel set-up is 3-5mm for various values of the explosive thickness. The calculation shows that when the explosive thickness is around 30mm, the temperature of welding point which is strongly related to the metallic jet formation is 2, 000-3, 500K for the given stand-off distance.

• Journal of the Korea Computer Graphics Society
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• v.16 no.3
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• pp.41-48
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• 2010

Photon mapping is a traditional global illumination method using many photons emitted from the light source for photo-realistic rendering. However, this method needs a lot of resources to perform tracing of millions of photons. Progressive photon mapping solves this problem. Typical progressive photon mapping performs ray tracing at first to find the hit points on diffuse surface of objects. Next, light source repeatedly emits a small number of photons in photon tracing pass, and power of photons in each sphere that has a fixed radius with the hit points in the center is accumulated. This method requires less resources than previous photon mapping, but it spends much time for gathering enough photons since each of photons progresses through a random direction and rendering high quality image. To improve the method, we propose photon probing that calculates variance of photons in the sphere and controls radius of sphere. In addition, we apply cone filter in radiance estimation step for reducing aliasing at the edges in result image.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.422-431
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• 2004

In recent years, different models in data delivery have been explored in mobile computing systems. Particularly, there were a lot of research efforts in the periodic push model where the server repetitively disseminates information without explicit request. However, average waiting time per data operation highly depends on the length of a broadcast cycle and different access pattern among clients may deteriorate the response time considerably. In this case, clients are preferably willing to send a data request to the server explicitly through backchannel in order to obtain optimal response time. We call the broadcast model supporting backchannel as hybrid broadcast. In this paper, we devise a new transaction processing algorithm(O-PreH) in hybrid broadcast environments. The data objects which the server maintains are divided into Push_Data for periodic broadcasting and Pull_Data for on-demand processing. Clients tune in broadcast channel or demand the data of interests according to the data type. Periodic invalidation reports from the server support maintaining transactional consistency. If one or more conflicts are found, conflict orders are determined not to violate the consistency(pre-reordering) and then the remaining operations have to be executed pessimistically. Through extensive simulations, we demonstrate the improved throughput of the proposed algorithm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.69-77
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• 1991

A collision-free trajectory planning algorithm using an iterative learning concept is proposed for dual robot arms in a 3-D common workspace to accurately follow their specified paths with constant velocities. Specifically, a collision-free trajectory minimizing the trajectory error is obtained first by employing the linear programming technique. Then the total operating time is iteratively adjusted based on the maximum trajectory error of the previous iteration so that the collision-free trajectory has no deviation from the specified path and also that the operating time is near-minimal. To show the validity of the proposed algorithm, a numerical example is presented based on two planar robots.

• Korean Journal of Cognitive Science
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• v.23 no.1
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• pp.25-46
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• 2012

When performing a monotonous task, one often experiences an urge to quit. This urge may vary depending on how long one has performed the task (a temporal factor) and on which particular component of the task one is carrying out (an event-based factor). Using the Stroop task and a working memory task, we examined changes in the urge to quit as a function of basic temporal (repetition) and event-based (cognitive conflict) factors. Consistent with the law of least work and recent theorizing, for the memory task, urges to quit were greater following difficult trials; for the Stroop task, urges to quit were greater following incongruent than congruent trials, but only during early/novice phases of performance, when responding is inefficient. This is a demonstration of an avoidance response toward cognitive conflict. Regarding temporal sources of quitting, urges to quit were greater for late task stages than early stages. These basic findings may illuminate the nature of the more 'hot' motivational struggles involving the delay of gratification.