• Journal of the Korean Applied Science and Technology
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• v.39 no.5
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• pp.614-622
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• 2022

This study attempted to investigate the effect of manufacturing a formulation with lavender extract and applying it to damaged hair. The experimental material was prepared by adding 0 g, 3 g 6 g, and 9 g of lavender extract to the perm base agent. The prepared formulation was applied to four damaged hair samples and compared and analyzed. As a measurement method for the effect on damaged hair, tensile strength, absorbance using methylene blue, and gloss were measured. Statistical analysis was conducted for the reliability of the research results. The tensile strength measurement results showed that the tensile strength of the sample applied with a formulation containing 6 g and 9 g at 8 levels increased, affecting damaged hair. As a result of absorbance analysis using methylene blue, it was found that the absorbance of all samples applied by adding extracts decreased, affecting damaged hair. The gloss measurement results showed that the addition of 9 g affected the damaged hair. In conclusion, it can be seen that lavender extract affects damaged hair, so it is considered to have an effect of improving Damage hair.

• Journal of the Korean Applied Science and Technology
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• v.41 no.1
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• pp.36-45
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• 2024

This study was to investigate the effect of manufacturing an avocado oil-added formulation and applying it to damaged hair. The experimental materials were prepared by adding avocado oil contents of 0 g, 3 g, 6 g, and 9 g to the perm base agent. It was applied to 4 damaged hair samples with the prepared formulation for comparative analysis. Tensile strength, absorbance using methylene blue, and gloss were measured as measurement methods for the effect on damaged hair. Statistical analysis was performed for the reliability of the research results. As a result of the tensile strength measurement, it was found that the tensile strength of the sample applied with the formulation containing 6 g and 9 g to the sample increased, affecting damaged hair. As a result of the absorbance analysis using methylene blue, it was found that the absorbance of all samples applied by adding oil decreased, affecting damaged hair. The gloss measurement result was found to affect damaged hair when 6 g and 9 g were added. The conclusion is that avocado oil affects damaged hair, so it is thought that it will have an effect of improving hair.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.408-413
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• 1995

We investigated the effect of mechanical backside damage upon minority carrier recombination lifetime measurement in Czochralski silicon substrate by laser excitation/microwave reflection photoconductance decay method. The intensity of mechanical damage was evaluated by X-ray double crystal rocking curve, X-ray section topography and wet oxidation/preferential etch methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the threshold full width at half maximum value which affect minority carrier lifetime measurement is about 13 secs.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.89-100
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• 2010

Although various methods for determination of damage threshold in rock have been suggested, clear damage thresholds were determined by some methods, but different thresholds were measured by other methods. We determined the damage thresholds in Hangdeung granite using all the methods suggested, and investigated the best methods, applicability and errors of each method. The crack initiation threshold and the crack damage threshold which are important in investigation of characteristics of crack development and failure were verified by field strength ratio method and long-term constant load test. The crack closure stress and the crack initiation stress were 57.5 MPa and 77.6 MPa, and the most exact values were yielded by crack volumetric strain. The secondary crack initiation stress was 90.6 MPa and AE event count and AE event count rate were the effective methods. The volumetric stiffness, AE event count and AE event count rate were the most effective methods for determination of crack coalescence threshold and crack coalescence stress was 110.3 MPa. The crack damage stress was 127.5 MPa and was measured correctly by volumetric stiffness and AE event count rate. The ratio between crack initiation stress and uniaxial compressive strength was 0.47 which was very similar with the FSR value of 0.46. The ratio between crack damage stress and uniaxial compressive strength was almost the same as the ratio between long-term strength and uniaxial compressive strength, indicating that the crack initiation stress and the crack damage stress measured were correct.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.220-225
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• 1998

레이다를 이용한 콘크리트 구조믈의 지진으로 인한 손상도를 파악하기 위해, 콘크리트의 전자기적 특성(dielectric properties)을 레이다 작용 주파수 대역인 200MHz에서 6GHz 영역까지 측정하였다. 이의 측정을 위해 실험실에서 콘크리트의 전자기적 특성 계측을 가능하게 하는 회로망분석기(network analyser)를 사용하였다. 콘크리트의 전자기적 특성은 open-ended coaxial probe를 회로망 분석기에 연결하여 측정하였고, 실험전 측정값을 보정(calibration)하는 기법을 찾아내었다. 주파수의 변화와 함께 콘크리트 시편안에 포함된 수분의 양을 조절함으로써, 실제 콘크리트 구조물이 가질 수 있는 상태를 시편을 통해 측정하였다. 측정결과는 콘크리트의 전자기적 특성이 주파수와 수분함량에 따라 변하는 것을 보여주었으며, 이는 레이다를 이용한 콘크리트 구조물의 지진 손상도 파악 방법 개발에 필요한 자료를 제공하였다.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.17-27
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• 1996

본 연구는 진동반응측정을 통해 구조물의 손상을 비파괴적으로 예측하는 분야에 속한다. 건물, 교량, 댐, 해양자켓, 원자력 발전소 등의 구조물에서 시기적절하고 정확한 손상의 발견은 치명적인 구조적 결함의 예방을 위해 필수적이다. 구조물의 진동반응을 측정하여 구조물의 손상발견을 예측하려는 연구는 지난 80년대 이후 활발히 수행되어 오고 있으며, 본연구는 구조물 고유진동수의 변화로 부터 구조물 강성도의 변화를 모니터링하는 연구분야에 속한다. 본 연구의 목적은 현존하는 시스템동일화 (system identification)에 의한 손상발견법의 적합성을 검증하는 것이다. 먼저, 실물실험된 삼차원 트러스교량이 선택되었다. 다음으로, 시스템 동일화 개념에 기초한 손상발견법이 요약되었다. 마지막으로, 시스템 동일화 손상발견법을 실물트러스에 적용하여 적합성을 실험하였다.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.129-140
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• 2000

최근들어 핵폐기물 지하처분장을 중심으로 터널굴착에 의한 주변 암반의 손상상태와 암반특성의 변화를 정량적으로 평가하기 위한 시도가 이루어지고 있다. 이는 암반의 지지력을 적극적으로 이용하는 NATM개념에 의해 터널을 시공할 셩우 안정성 해석과 최적 보강설계를 위해 필수적인 사항으로 고려된다. 그러나 현재까지 암반 손상영역을 평가하기 위해 제시된 여러 방법들은 아직까지 그 적용성과 타당성이 충분히 검증되지 못한 실정이다. 이 연구에서는 코어시추, 실험실시험, 발파진동측정, 보어홀 카메라 등의 여러 방법에 의해 손상영역을 정량적으로 평가하고자 하였으며 가 방법의 적용성을 검토하였다. 암반상태 및 발파조건을 달리하여 시험발파를 수행하였으며 발파 후에 터널벽면에 수직하게 시추를 하여 암석코어를 채취한 뒤 손상정도에 따른 암석의 물리적, 역학적 특성들？ 변화를 정량적으로 나타내고자 하였다. 코어 채취후 시축공에 보어홀 카메라를 사용하여 손상영역을 시각적으로 판별하고자 하였으며 발파진동 측정결과로부터 손상영역을 예측하고 채취한 암석시표에 대한 실험실시험 결과와 비교하여 적용성을 검토하였다.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.570-575
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• 2021

Since humans live while feeling rich in their five senses, care must be taken not to damage their hearing in order to lead a happy life. Hearing damage suffered in a living environment is common in a partial band where a specific frequency band is first damaged. However, since the initial pain of hearing damage does not appear much, it is difficult to determine the symptoms in the early stages. In this paper, we proposed a high-speed measurement method that can easily and quickly self-measure hearing damage through a simple app. In this method, 9 pure tones compensated for gain for each voice soub-band are alternately heard in both ears, so that one's own hearing damage can be detected at high speed. When 18 tone pulses were heard for 30 seconds per person, 1 out of 12 subjects was identified as suspected of partial hearing damage. And when the test subjects were informed of the hearing determination method for the number of hearings, the participants themselves immediately determined whether their hearing was damaged. This measurement method simply judges the hearing of both ears within 30 seconds with a smart phone, so that hearing measurements that took more than 10 minutes in hospitals are relatively accurate, and it was found that hearing health can be maintained while reducing time and costs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.35-42
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• 1990

A method for the damage assessment of a structure by an inverse modal perturbation technique is studied. The first few natural frequencies and mode shapes of the damaged structure are assumed to be known. Then, the perturbation equation is formulated for the changes of the modal properties due to the stiffness changes. The stiffness changes due to damages are evaluated, using optimization techniques. Example analyses are carried out for several cases of stick models and a truss model. Results indicate that the present method yields very reasonable estimates for the element stiffness changes.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.114-117
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• 2002

현재 개발 중에 있는 비파괴 검사법인 Tapping Sound Analysis 의 실험적 검증을 위한 연구를 수행하였다. 손상이 없는 복합재료 구조물과 손상이 있는 복합재료 구조물에 대한 타격 실험을 통해 타격음과 타격력을 측정하여 비교하였다. Wavelet packet transform에 근거한 특성 추출법을 이용하여 타격음으로부터 손상 판단을 위한 특성을 추출하였다. 손상이 없는 구조물과 손상이 있는 구조물의 특성을 비교하기 위해, 특성 지수를 정의하였다. 정의된 특성 지수를 이용하여 손상이 없는 구조물과 손상이 있는 구조물의 타격음의 차이를 하나의 실수로 표현하였다.