• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.174-174
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• 2003

Highly (111)-oriented PZT [Pb(Zrl-xTix)O3] thin films in the Zr-rich rhombohedral phase-field were successfully fabricated on Pt(111)/Ti/SiO2/Si substrates by combining PLD method with sol-gel process. These highly (111)-oriented films can be used as model systems for polarized Raman scattering study of PZT in the rhombohedral-Phase field because the (111)-direction is the principal off-center axis of the rhombohedral ferroelectricity. For this purpose, we have fabricated PZT films employing two distinctive compositions : one with Zr/Ti = 90/10 (abbreviated as PZT90/10) and the other with Zr/Ti= 60/40 (PZT60/40). The PZT90/10 film belongs to the octahedrally distorted FR(LT) phase with a cell-doubled structure, whereas the PZT60/40 is in the high-temperature FR(HT) phase-field at room temperature. To clearly separate E(TO) phonon modes from Al(TO) modes of the (111)-oriented rhombohedral film, we have suitably devised Z(X,Y)Z and Z(X,X)Z backscattering geometries for E(TO) and Al (TO), respectively. The polarized scattering experiment demonstrated that both types of (111)-oriented rhombohedral films closely followed the Raman selection rule.

• 대한인간공학회지
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• 제17권1호
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• pp.115-123
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• 1998

We study the ski wear which are compared at the materials and the designes and their human physiological and phychological response during exercise in a cold and air-conditioned enviroments. Five men exercises in the experiment room with four types of ski-wears : two of one-piece and two of two-piece : two of special material and two of a normal material, respectively. We keep the environment at $-5^{\circ}C$ and speed of 3.6 mile/hr during the measurement of 13 points, which is a mean model of the Muju ski-resort at January 1996. We conclude the followings : 1. The ski-wear with special materials have higher than the normal type at mean skin temperature and rectal temperature. 2. Changes of temperature withing the clothes during the exercise is small, but the humidity within the clothes abruptly increases because of the weight loss. 3. Type A ski-wear with the special material has $295.5g/m^2hr$ weight loss, which is higher, and type D ski-wear is smaller 4. The special material shows comfortable in the thermal sensation. 5. In the design aspect of the ski-wears, the two-piece type ski-wear shows higher skin temperature and temperature & humidity within the clothes than the one-piece type due to the effect of the multiplicity.

• 설비공학논문집
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• 제18권11호
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• pp.933-940
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• 2006

In this study multi-zone modeling program CONTAM 2.4 developed by NIST is used for estimating the air disinfection rate of the interior of a room which is set up the indoor air disinfection system with filter and ultra violet germicidal irradiation (UVGI). Developed models those enable to predict the transmission of air home contagion such as bacteria and fungus generated in our daily life are useful model for designning air cleaning & ventilation system of building. Also, results indicate that these models are enable to compute the real situation that is almost impossible of carrying out experiment in an actual condition due to biohazard problems and suggest that engineers will use these models as a design tool for the future immune building system.

• International Journal of Advanced Culture Technology
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• 제9권1호
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• pp.129-135
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• 2021

In this study, we built a mock-up of an indoor garden for private use and vertical gardens were installed on the walls of this indoor garden model. The purpose of this study is to examine the types of plants for best fit for growth and nurture in vertical garden and to identify the effects of indoor air quality improvement by these plants. As the result of the experiment, 22 species out of 32 species previously used for indoor garden was selected to be suitable for vertical gardens of a personal indoor garden. 10 species were found to be inappropriate for a personal indoor garden in terms of ornamental value, growth status and maintenance. The effect of plants on reducing CO2 has been proven by many studies. Also, through photosynthesis, plants combine CO2 with water and produce sugars and O2 (oxygen). Everyone accepts this fact. In nature, the production of oxygen is so important that without plants we would soon use it up and die. From the NASA Fact Sheet we know that air contains 20.95% O2 and 0.04% CO2. If you had enough plants in a room to use up all of the all of CO2 and convert it to oxygen, the oxygen levels would increase from 20.95% to 21%. This increase is difficult to detect and would have no effect on humans.

• Tribology and Lubricants
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• 제32권4호
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• pp.113-118
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• 2016

As an economic, high quality, and highly reliable gear with low noise and low vibration is demanded, an overall finite element analysis regarding a gear is required. Also, an infrared thermography test, which is a quantitative testing technique, is demanded for safety and longer lifespan of gear products. In order to manufacture a gear product or to determine safety of a gear being used, it is necessary to precisely determine ingredients of a material constituting a gear and detect any internal defect. This study aims to realize a design that minimizes the spur gear displacement with respect to power during its rotation and ensures the spur gear control capacity by using a 3D model and the midasNFX program. This facilitates the assessment of the possibility of cracking by evaluating the stress intensity and focusing on the integrity of the spur gear. We prepare the specimen of the spur gear based on the possibility of cranking as per the result of the structural interpretation from an infrared ray thermal measuring technique. After cooling the spur gear, we perform experiments using thermography and halogen lamps and analyze the temperature data according to the results of the experiment. In the experiment which we use thermography after cooling, we find a rise in the temperature of the room. As a result, the defective part show temperatures lower than their surroundings while the normal parts have temperatures higher than the defective parts. Therefore, it possible to precisely identify defective part owing to its low temperature.

• 한국농공학회논문집
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• 제55권6호
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• pp.135-144
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• 2013

Ventilation efficiency has an important role in agricultural facilities such as greenhouse and livestock house to keep internally optimum environmental condition. Age-of-air concept allows to assess the ventilation efficiency of an agricultural facility according to estimating the ability of fresh air supply and contaminants emission using LMA and LMR. Most of these methods use a tracer gas method which has some limitations in experiment like dealing unstable and invisible gas. Therefore, the aim of this study was to develop a straightforward method to calculate age-of-air values with CFD simulation which has the advantage of saving computational time and resources and these method can solve the limitations in experiment using tracer gas method. The main idea of LMA computation is to solve the passive scalar transport equation with the assumption that the production of the time scalar throughout the room is uniform. In case of LMR calculation, the transport of the time scalar was reversed compulsively using UDF. The methodology to validate the results of this study was established by comparing with preceding research that had performed a computing LMA and LMR value by laboratory experiments and CFD simulations using tracer gas. As a result, the error was presented similarly level of results of preceding research. Some big errors could be caused by stagnated area and incongruity turbulence model. while the computational time was reduced to almost one fourth of that by preceding research.

• 한국재난정보학회 논문집
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• 제19권2호
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• pp.439-450
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• 2023

연구목적: 국내에서 소방점검을 시행시 바닥면적 400m2 미만일 경우 공기유입구와 배출구간의 직선거리 5m이상 하라는 소방법규에 위반되는 대상물들이 있으며 이러한 이유를 분석하고 관련 소방법규의 필요성을 뒷받침 하기 위해 모형실험연구를 시행한 논문이다. 연구방법: 국내소방 대상물을 조사확인 하였고, 국내 및 해외논문 및 정책, 법규를 문헌고찰 하였으며, 400m² 미만의 거실에서 공기 유입구와 배출구간의 직선거리 5m 이하와 5m이상인 공간을 선정하여 모형실험 을 통해 분석하였다. 연구결과: 국내 소방법규(NFPC-화재안전성능기준)를 고찰 하였을 때 바닥면적 400m² 미만일 경우 공기유입구와 배출구 간의 5m 이상으로 이격 거리가 규정되어있지 만 실제 조사해 본 결과 이격 거리를 지키지 못하는 소방대상물이 있는 것으로 확인되었다. 또한 5m 이상의 직선거리에 대한 해외 소 방법규에 대한 논문 고찰을 해봤을 때 공기유입구와 배출구간의 직선거리에 대한 규정이 없는 것으로 나타났지만, 모형실험 한 결과 공기유입 구와 배출구간의 직선거리가 5m이상 일 때가 5m미만 일 때보다 배출속도가 우수한 것으로 나타났다. 결론: 본 연구에서는 공기유입구와 배출구간의 직선거리에 대한 제연설비 성능비교로 해외 소방법규 를 조사하였을 때 직선거리에 대한 강제규정이 없지만 국내 소방법규(NFPC_화재안전성능 기준)에 서는 5m이상을 해야 한다는 법규를 뒷받침하는 근거를 마련하는 논문이다. 앞으로 설계 단계에서 이를 반영하여 소방 감리의 책임과 부담을 줄여줄 수 있는 토대가 마련되길 바란다.

• 대한물리치료과학회지
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• 제15권4호
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• pp.27-34
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• 2008

Background: This study was designed to analyze Repetitive dorsiflexion exercises in ankles have effects on the active range of flexion and extension motion through lumbar, cervical spine and ankle, wrist joints. Methods: 30 female college students in their twenties who frequently wear high heels participated the number of the experimental group was 15 persons and the number of the control group was 15 persons. They did exercise at the physical therapy room in M college, from the 8th of March to the 11th of April 2007. The experimental group had used the model of dorsiflexion repetitive exercise three times per week, for 4 weeks, but the control group did not exercise at all. In the sagittal plane active ROM of the these spine and joints were measured before and after the experiment using a digital goniometer. The results of two groups were compared and analyzed using paired T-test. Results: The active range of flexion and extension motion of the vertebra(especially lumbar flexion) and distal joints were significantly different in exercise group(p<.05). Conclusion: The model of repetitive dorsiflexion exercise of the ankle joint had positive effects on improving the active range of flexion and extension motion of the lumbar vertebra and distal joints of limbs. The results suggest that the repetitive dorsiflexion exercise is useful and also effective therapy for improving motion in women usually wearing high-heel.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.168-168
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• 1999

Recently, Fe/Si multilayered films (MLF) have been a focus of interest due to the strong antiferromagnetic (AF) coupling observed in such kind of MLF originates from the same nature as in the metal/metal MLF. In particular, a question of whether the spacer layer in the Fe/Si MLF is metallic or semiconducting is of interest. In spite of various experimental techniques envolved in the study, the chemical composition and the properties of the interfacial regions in the MLF exhibiting the AF coupling is still questionable. The nature of the AF coupling and the interfacial properties of Fe/Si MLF are investigated in this study. A series of Fe/Si MLF with a fixed nominal thickness of Fe(3nm) and a variable thickness of Sk(1.0-2.2nm) were deposited by RF-sputtering onto glass substrates at room temperature. The atomic structures and the actual sublayer thicknesses of the Fe/Si MLF are investigated by using x-ray diffraction. The magnetic-field dependence of the equatorial Kerr effect clearly shows an appearance of the AF coupling between Fe sublayers at tsi = 1.5 - 1.8 nm. the drastic discrepancies between the experimental magnetooptical (MO) and optical properties, and based on the assumption of sharp interfaces between Fe and Si sublayers leads to a conclusion that pure si is absent in the AF-coupled Fe/Si MLF. Introducing in the model nonmagnetic semiconducting FeSi alloy layers between Fe and Si sublayers or as spacer between pure Fe sublayers only slightly improves the agreement between model and experiment. A reasonable agreement between experimental and simulated MO spectra was reached with using the fitted optical properties for the spacer with a typical metallic type of behavior. The results of the magnetic properties measured by vibrating sample magnetometer and magnetic circular dichroism are also analyzed in connection with the MO and optical properties.

• 자원리싸이클링
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• 제32권2호
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• pp.33-42
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• 2023

금속 에멀젼(metal emulsion)은 제강 공정의 효율성을 높이는 방법으로 수십 년 동안 연구되어 왔습니다. 본 연구는 육안으로 관찰하기 어려운 고온 실험의 단점을 보완하기 위해 상온에서 관찰 가능한 수모델을 이용하여 수행하였다. 슬래그 내 금속 에멀젼의 대신하여 증류수를 실리콘 오일에 적하하여 운동량 균형 방정식에 의한 계산 결과와 비교하는 실험을 하였다. 물방울의 하강 속도는 물방울의 직경과 유체(실리콘 오일)의 점도가 증가함에 따라 감소하였다. 교반 조건에서 실리콘 오일에서 물방울의 하강 속도를 시뮬레이션하기 위해 유체(실리콘 오일)의 유속을 입자 이미지 속도계(PIV) 방법으로 측정하였다. 물방울의 하강 속도 계산은 점성 실리콘 오일을 교반하거나 교반하지 않고 측정된 값과 잘 일치하였다.