I
praised the fact that I was born in a good land and had happy seasons because
the four seasons are distinct: spring, summer, fall, and winter, but I also had
many regrets. First of all, I needed a closet, the glass windows had to be
thick, and I had to install both a boiler and an air conditioner. And because
there were often icy roads, I worried about whether I should use car snow tires
or chains. Because accidents can easily occur when it's slippery...
단진자와 현의 고유진동수 (시계추와 기타줄) -------------------------------------------------------------------------------------------------------------------------- 시계
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지진과 철도진동(노면진동)의 차이
대형건물은 생활의 안락감, 경제성, 환경문제, 안전성 그리고 기존설계의 변경 측면에서 매우 엄격하므로 면진장치를 적용한 설계시 정밀한 해석이 선행되어야 한다.
대형건물을 지진으로부터 면진시키는 방법이나 원리는 철도에서 발생하는 지반의 진동을 면진시키는 것과 같으나 다음과 같은 관점에서 다르게 취급되고 있다. 즉,이 것이 지진과 철도진동..https://contents.premium.naver.com/bisope/visope/contents/241107075044285ts
철도의 진동과 지진(지반진동)의 차이
철도의 진동과 지진(지반진동)의 차이에 대하여 --------------------------------------------------------------------------------------------------------------------------
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Frequency와 Hz
대표적인 Hz의 사용예
(지진 2Hz, 모터회전수 29Hz, 소리 4kHz, 초음파 43kHz, FM 라디오 89MHz, 핸드폰 1.2GHz, 적외선 430 THz, Xray 3x10¹⁸ Hz...)..
비교샘-주파수(frequency)와 Hz 주기는 무엇이고 주파수는 무엇인가? 주파수는 어떤 의미인가? Hz를 알고 있다면 RPM과는 어떠한 관계가 있을까? 인간은 소리 몇 Hz에 가장 민감한가? 이러한 질문에 대한 진동소음의 기초 단위를 설명하였다.
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비교를 통한 러닝 그리고 분류, 군집
인공지능이 편의성을 추구하는 인간을 위해 기계의 결함을 진단하고 고장을 예측하는데 많은 연구가 가지에서 전세계적으로 진행중이다. 하지만 여기에는 뭔가 다른 점이 있다. 기계의 결함진단은 모두 전문가들이 수행하는 영역으로서 기존의 다른 영역처럼 비전문가의 영역(노동집약, 단순분리영역, 행동예측, 통계처리 등)의 경우와 다르다...https://contents.premium.naver.com/bisope/visope/contents/241119071457042ia
AI의 핵심-비교원리
AI의 핵심은 비교원리 -------------------------------------------------------------------------------------------------------------------------- 한민족의 성공 원동력은 전
BISOPE series 63- Graphs related to
amplitude and frequency---------------------------------------------------------------------------
There
is an object that changes its position and repeatedly moves back and forth
around a certain standard. On the other hand, there are objects that end with a
single push or pull. Which one takes more strength? If you look closely at the
fitness equipment nearby in your daily life, you will see that what you moved
with effort must be returned to its original position before you can apply
force in the same direction in the next exercise. In fact, which force is
applied is not that important when comparing two movements. However, the key is
how much greater force is applied and how often. We understand that all
physical waves appear as noise in the air and as vibration (repetition) in
objects. And if you draw it as a two-dimensional graph, it can be expressed
directly as the X and Y axes. This is ‘change in size over time’.
It
is said that the horizontal vibration on the NDE side is high. Where should I
look?
Looking at the components of a rotating
machine, they can first be divided into the
driving part (driving part) side, the driven part (driven part) side, and the coupling (direct coupling, buffer type, belt,
etc.) that connects them. Another connection element may be a gearbox that requires an additional separate coupling.
Since each component is a machine that is all connected and rotates together,
the speed may be different, but vibration is transmitted between each other,
and if any connecting part is incorrect or misaligned, the entire machine
(equipment) is affected by vibration. Therefore, determining what the vibration
is like at a certain location is a very important appointment. Among these, DE and NDE are words that you must know and understand.
DE, NDE and Outboard, Inboard
Naming the location of the
facility is an issue that has already been------
Unlike temperature measurement, where you can select
only Celsius or Fahrenheit and press a button, you need to know a lot about
'vibration' before measuring. How to select units and how far is the frequency range? What
are the types of sensors and how to attach them? Also where? in which
direction? Everyone should know how to measure. As a metaphor, 'knowledge
is something that is easy for those who know it, unlike wisdom that is
difficult even if you know it.' If you know about the vibration, it is easy to
measure the selectivity of the instrument.
Distinct difference between vibrometer
(vibrometer and frequency analyzer FFT vibration analyzer)
Recent vibrometers that can perform simple spectrum
frequency analysis and trend storage are being sold at low prices, but in
general, vibrometers do not have as precise or diverse functions as FFT
(vibration frequency analyzer). Therefore, it is necessary to know the
practical optimal knowledge that can identify these differences, and refer to
the following.
item
vibrometer
Frequency
analyzer (FFT, multi-channel vibration analyzer)
Appearance
output
Types and uses of instrumentation
Magnet-attached or probe-type machine
surface vibration measurement, machine condition management
Select
the number of simultaneous measurement channels, whether to measure FRF
(resonance), machine diagnosis, long term recording (DAQ), rotor dynamics,
front-end or hand held, for Labs and machine analysis
Sensor selection
-The magnet attached type is better than
the probe stick type because measurement stability and high frequency are
possible.
-Sensitivity modifiable instrument (high sensitivity,
high impact measurement possible)
-Sensitivity
modifiable instrument (high sensitivity, high impact measurement possible)
-For low
frequency detection (using displacement sensor and DC sensor, or using
acceleration of 500mV/g or higher)
-General
type acceleration sensor (100mV/g)
-High
impact acceleration sensor (10mV/g)
Unit
This data is very
realistic and it is the result confirmed in the actual domestic industrial
field, but it can be subjective and biased, so please refer to it.
In selecting a transducer, the most important priority
would be sensitivity and 'Frequency range'.
To
explain the vertical axis in the graph of amplitude and frequency, it would be
nice if one sensor could measure all amplitudes, but it can never be done
because it depends on the sensitivity. To explain the horizontal axis in this
way, if all sensors can measure all frequencies, there is no reason to select a
sensor. This is because each type of vibration sensor, further subdivided, each type of vibration sensor
(including an acceleration sensor) has its own frequency range of an area where
measurement is accurate. This is called the frequency range.
Frequency range
The sensor indicates the range of measurable frequencies
(e.g., acceleration sensor: 0.5 to 10 kHz), and the definition of this range is
slightly different depending on the user, so that the maximum and minimum frequency
ranges corresponding to the 'accurate zone' of the measurement can be selected.
This
frequency range is 'a reliable area where the sensor can output a properly
matched signal; It means 'the range of frequency response accuracy according to
the frequency sensitivity deviation', and although the meaning is slightly different from the
non-linearity of the sensor, this reliable area can be expressed as a linear
area.
Looking at the criterion of error amplitude related to
the frequency domain, select the rate of change of the amplitude limit that can
be judged by the presence or absence of an error, eg) ±3dB, ±5%, ±10%, etc.,
and the applicable frequency at this time is ..........
If
the desired 'unit' of vibration is selected as a result for the evaluation, the
next step is to select an appropriate 'sensor'. First of all, it is necessary
to check whether contact attachment is possible at the location to be
measured... or whether the attachment method is appropriate. For example, in
the case of high frequency (more than 5000Hz), the magnetic attachment method
is not appropriate, and if you want to measure the behavior of an axis, it is
difficult to use a contact sensor. Also, if you try to measure the speed and
measure 5 Hz using a coin type speed sensor, you will get an amplified error
signal. This is because the characteristics of each sensor are different depending
on the amplitude band, frequency band, resonance band, etc.
Selection of displacement, velocity, and acceleration sensors
such as amplitude units
Since the output voltage or current is proportional to
each unit, the selection of the unit is not very different from the selection
of the sensor. Sensors mainly used for diagnosing and monitoring equipment
1. Eddy current type displacement sensor (Proximity) that
directly measures the behavior of a shaft supported by a sleeve bearing in a
non-contact manner.
2. Accelerometer, which propagates shaft vibration to
rolling bearing and measures it indirectly by contact method outside the
bearing housing (indirectly transmitted to the housing by impact of the bearing
connected to the shaft)
3. There is a velocity transducer that works without power.
However, among these, the speed sensor is very precise,
but has a weakness limited to the range of 10 to 1000 Hz because it has a
natural frequency in the upper and lower frequencies, which is why displacement
sensors and acceleration sensors are widely used. (If it is out of this frequency
range, an erroneous or amplified value is output.)
A sensor (transducer) is one of the components
of a system that is mainly used by companies that use sensors to research,
diagnose or manufacture monitoring equipment. Since the manufacturer has
selected a sensor that fits a specific principle, the manufacturer has
accumulated a lot of engineering grounds for this. In many cases, the level of
engineering is considerably deeper than that of academia because it must be
required and the reliability of the measurement needs to be verified.
Above all, this principle can be considered as the most
basic sensor selection method. The reason why a displacement sensor is
called a displacement sensor and an acceleration sensor is called an
acceleration sensor is that each sensor generates an electrical output
'proportional to the amplitude unit'. It's because you do it. For example, since the value
converted to displacement by outputting acceleration vibration with an
acceleration sensor and integrating twice is not very accurate (especially when
it is not a sine wave), it is better to measure acceleration vibration with an
acceleration sensor, and displacement vibration It is basic to measure with a
displacement sensor. However, there are cases where it is absolutely necessary to
evaluate the health of a machine or the vibration of a building with the
'velocity' value, which is used as the most evaluation unit in academia and
industry, so this only allows integration from the acceleration sensor once.
Because the speed sensor isn't cool...
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