• 전자공학회논문지
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• 제53권6호
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• pp.29-36
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• 2016

별도의 RF 소스가 센서 노드에게 에너지를 공급하는 무선 수동형 센서 망은 배터리 없이 영원히 동작할 수 있는 망이다. 그러나 영원한 수명에 대한 기대와 달리 무선 수동형 센서 망은 아직 에너지의 희소성, 에너지 수신과 데이타 전송의 동시불가성, 자원 활용의 비효율성 등 많은 문제를 안고 있다. 본 논문에서는 패킷 상실에는 관대하지만 패킷의 적시 전달을 요구하는 서비스를 제공하는 무선 수동형 센서 망을 다룬다. 이러한 망에서 여러 센서 노드들이 하나의 싱크 노드에게 패킷들을 전달하도록 현실적 제약을 인식하여 framed and slotted ALOHA에 기초한 경합형 MAC 방식을 고려한다. 이어서 지리적으로 흩어져있는 센서 노드들이 전송한 패킷들이 경로 손실을 겪어 결국 capture 현상이 빚어질 때 MAC 방식이 얻을 수 있는 망전체 throughput을 조사한다. 특히 두 센서 노드만이 망에 있을 때 망 전체 throughput의 정확한 공식을 closed form으로 도출한다. 마지막으로 설계 parameter들을 조절하여 최대의 망 전체 throughput을 취하도록 경합형 MAC 방식을 최적화한다.

• International Journal of Precision Engineering and Manufacturing
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• 제6권4호
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• pp.37-43
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• 2005

This paper presents a hybrid control algorithm for the active noise control in the rectangular enclosure using an active/passive foam actuator. The hybrid control composes of the adaptive feedforward with feedback loop in which the adaptive feedforward control uses the well-known filtered-x LMS(least mean square) algorithm and the feedback loop consists of the sliding mode controller and observer. The hybrid control has its robustness for both transient and persistent external disturbances and increases the convergence speed due to the reduced variance of the jiltered-x signal by adding the feedback loop. The sliding mode control (SMC) is used to incorporate insensitivity to parameter variations and rejection of disturbances and the observer is used to get the state information in the controller deign. An active/passive smart foam actuator is used to minimize noise actively using an embedded PVDF film driven by an electrical input and passively using an absorption-foam. The error path dynamics is experimentally identified in the form of the auto-regressive and moving-average using the frequency domain identification technique. Experimental results demonstrate the effectiveness of the hybrid control and the feasibility of the smart foam actuator.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.387-394
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• 2003

A compromise between passive and active control systems has been developed recently in the form of semi-active control systems. Semi-active control systems maintain the reliability of passive control systems while taking advantage of the adjustability of an active control system. This paper presents the results of an experimental study to evaluate the performance of a semi-active orificed fluid damper. The semi-active orificed fluid damper considered is a two-stage damper with normally open solenoid valve. Through a series of experimental tests, characteristics and performance of the damper is investigated.

• 한국융합학회논문지
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• 제8권7호
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• pp.349-356
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• 2017

본 연구는 골관절염을 앓고 있는 여성을 대상으로 24주간의 수동적 수중재활운동을 통하여 효율적인 골관절염 예방 재활 프로그램 및 운동처방의 양식에 지침을 제공하는데 목적이 있다. 본 연구의 대상자는 K 정형외과 전문의에게 골관절염이라는 진단 받고 골관절염으로 인한 통증으로 병원을 3회 이상 내원한 자 중 실험군은 수동적 수중재활 운동집단(CG, n=10)과 비교군(AREG, n=10)으로 선정하였다. 연구결과 집단 내 좌우 어깨 높이(shoulder height) 변화는 수동적 수중재활운동군에서 유의한 차이가 있었다(p<.001). 집단 내 좌우 견갑골 하각 무늬의(sacpula patterns inferior) 변화는 수동적 수중재활운동군에서 유의한 차이가 있었다(p<.001). 집단 내 좌우 골반 하각 무늬의(pelvis patterns inferior) 변화는 수동적 수중재활운동군에서 유의한 차이가 있었다(p<.001).

• 보건행정학회지
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• 제17권1호
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• pp.75-93
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• 2007

This research purposed to analyse the diversity of the long-term care system based on the dependency/independency of the aged. For this purpose, we divided the long-term care systems to three components; form of benefit, generosity of benefit and delivery system. Form of benefit is whether the benefit is cash or in-kind, and the generosity of benefit is related to the level and coverage of benefit. The last concerned to focus on provider and user selection. According to this, we tried to make an ideal type of long-term care in the perspective of citizenship and consumerism. As a result, we established four types of long-term care system; active citizen type, passive citizen type, latent citizen type, and family dependent type. And we investigated Austria, Sweden, Germany and Korea for each type empirically.

• 한국환경보건학회지
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• 제35권6호
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• pp.500-509
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• 2009

Passive samplers have been used for many years for the sampling of organic vapors in work environment atmospheres. Currently, all passive samplers used in domestic occupational monitoring are foreign products. This study was performed to evaluate variable parameters for the development of passive organic samplers, which include the geometry of the device and diffusive length for the sampler design. Four prototype diffusive lengths; A-1(4.5 mm), A-2(7.0 mm), A-3(9.5 mm), A-4(12.0 mm) were tested for adsorption performances to a chemical mixture (benzene, toluene, trichloroethylene, and n-hexane) according to the US-OSHA's evaluation protocol. A dynamic vapor exposure chamber developed and verified by related research was used for this study. The results of study are as follows. The results in terms of sampling rate and recommended sampling time test indicate that the most suitable model was A-3 (9.5 mm diffusive lengths on both sides) for passive sampler design in time weighted average (TWA) assessment. Sampling rates of this A-3 model were 45.8, 41.5, 41.4, and 40.3 ml/min for benzene, toluene, trichloroethylene, and n-hexane, respectively. The A-3 models were tested on reverse diffusion and conditions of low humidity air (35% RH) and low concentrations (0.2 times of TLV). These conditions had no affect on the diffusion capacity of samplers. In conclusion, the most suitable design parameters of passive sampler are: 1) Geometry and structure - 25 mm diameter and 490 $mm^2$ cross sectional area of diffusion face with cylindrical form of two-sided opposite diffusion direction; 2) Diffusive length - 9.5 mm in both faces; 3) Amount of adsorbent - 300 mg of coconut shell charcoal; 4) Wind screen - using nylon net filters (11 ${\mu}m$ pore size).

• Corrosion Science and Technology
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• 제9권1호
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• pp.20-28
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• 2010

According to the bipolar model, ion selectivity of some species in the passive film is important factor to control the passivation. An increase of cation selectivity of outer layer of the passive film can stabilize the film and improves the corrosion resistance. Therefore, the formation and roles of ionic species in the passive film should be elucidated. In this work, two types of solution (hydrochloric or sulfuric acid) were used to test high N and Mo-bearing stainless steels. The objective of this work was to investigate the formation of oxyanions in the passive film and the roles of oxyanions in passivation of stainless steel. Nitrogen exists as atomic nitrogen, nitric oxide, nitro-oxyanions (${NO_x}^-$), and N-H species, not nitride in the passive film. Because of its high mobility, the enriched atomic nitrogen can act as a reservoir. The formation of N-H species buffers the film pH and facilitates the formation of oxyanions in the film. ${NO_x}^-$ species improve the cation selectivity of the film, increasing the oxide content and film density. ${NO_x}^-$ acts similar to a strong inhibitor both in the passive film and at active sites. This facilitates the formation of chromium oxide. Also, ${NO_x}^-$ can make more molybdate and nitric oxide by reacting with Mo. The role of Mo addition on the passivation characteristics of stainless steel may differ with the test environment. Mo exists as metallic molybdenum, molybdenum oxide, and molybdate and the latter facilitates the oxide formation. When nitrogen and molybdenum coexist in stainless steel, corrosion resistance in chloride solutions is drastically increased. This synergistic effect of N and Mo in a chloride solution is mainly due to the formation of nitro-oxyanions and molybdate ion. Oxyanions can be formed by a 'solid state reaction' in the passive film, resulting in the formation of more molybdate and nitric oxide. These oxyanions improve the cation selectivity of the outer layer and form more oxide and increase the amount of chromium oxide and the ratio of $Cr_2O_3/Cr(OH)_3$ and make the film stable and dense.

• 영어어문교육
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• 제17권4호
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• pp.177-191
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• 2011

This paper examines nursing professionals' English abstract to learn their preferences towards tense and voice choices. A total of 24 abstracts, completed reviews to be published by the editorial board members of the Korea Industrial Nursing Association, were analyzed for the study. Each sentence in the four parts of the abstract (Purpose, Methods, Results, and Conclusion) was examined and classified into active/passive voices, and present/past/present perfect tenses. Verbs were then further identified to see which ones were commonly preferred to state the objectives of the study, methods, and to draw conclusions. Hedging expressions in Conclusion were also examined. The results of the present study revealed that Purpose was mostly (79%) stated in the past tense with slight use (17%) of the present tense in the form of 58% active and 42% passive voice whereas Methods were dominantly (96%) illustrated in the past tense with preference of mixed active and passive voice. The Results were also preferably (92%) stated in past tense and Conclusion in both present and past tense. Verbs used by these nursing professionals seemed diverse; however, hedging appeared to be narrowly limited to a few expressions including suggest and should. More diverse English hedging expressions need to be taught at least college level writing so that the EFL learners and writers can have a better understanding of presenting statements in an appropriate level of caution, confidence, or uncertainty.

• 근관절건강학회지
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• 제25권3호
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• pp.167-175
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• 2018

Purpose: The aim of this study was to test the effects of passive exercise on upper extremities muscle spasticity, finger edema, and depression for chronic stroke patients. Methods: A non-equivalent pretest-posttest design was employed for this study. The subjects were 30 elderly patients who were hospitalized to treat chronic stroke. 15 patients were assigned to the experimental and control groups respectively. Passive exercise for 20 minutes per day, five days a week for 8 weeks (total 40 times) was provided for the experimental group. Outcome measurements included manual spasticity test to measure upper extremities' muscle spasticity, the ring measurement method for finger edema and the Korean version of Short-form Geriatric Depression Scale (SGDS-K) for depression. Results: The upper extremities' muscle spasticity (Z=-2.52 p=.012) and the degree of depression (F=5.56, p=.006) in the experimental group were significantly reduced compared to those of the control group. But the degree of finger edema did not significantly differ between the two groups (F=1.46, p=.240). Conclusion: Passive exercise for upper extremities should be encouraged for elderly patients with chronic stroke to enhance the upper extremities' functional capacity as well as depression.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.3435-3449
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• 2024

Considering that system analysis codes are used for the evaluation of the performance of Passive Safety Systems (PSSs), it is important to investigate the capability of the system analysis code to reliably predict the heat transfer and natural circulation flow, which are the main phenomena governing the performance of a PSS. Since MARS-KS has been widely validated for heat transfer models, this study focuses on evaluating its capability to predict the single and two-phase pressure drops and natural circulation flow. The straight pipe simulation results indicate that the pressure drop predictions are reliable within ±5 % error margin for the single-phase flow and the errors of pressure drop up to - 30 % for the two-phase flow. Through single-phase natural circulation flow analysis, it is concluded that the use of the appropriate K-factor modeling based on the flow regimes is important since the natural circulation flow rate in MARS-KS is mainly affected by the form loss factor modeling. With two-phase natural circulation flow analysis, this study emphasizes the behavior of the system could change significantly depending on the two-phase wall friction and pressure loss modeling. With the analysis results, modeling considerations for the PSS performance evaluation with the system analysis codes are proposed.