• 대한치과교정학회지
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• 제19권3호
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• pp.123-133
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• 1989

To predict the pubertal growth peak in stature and study the skeletal maturity degree using hand-wrist radiograph, the author used the 70 malocclusions (male 24, female 46). After longitudinal measurement of stature and skeletal maturity indicators of hand-wrist radiographs were taken during 4 years, the rsults were as follows. 1) The pubertal growth peak in stature occurred mainly at SMI 6-7 (56.5%) in female, SMI 5-6 (37.5%), 6-7 (37.5%) in male (Table 5). 2) It was suggested that the pubertal growth peak in stature was already passed, if SMI 8 occurred. 3) Ages of SMI in female were about 2 years earlier than those of SMI in male, and the sexual difference was gradually decreased in puberty. 4) Duration of SMI was longest at SMI 6-7 in both sex and the mean was 8.5 months. After this stage, the velocity of skeletal maturity in female was decreased than in male. 5) The correlation coefficient between each SMI and pubertal growth peak was very high (Table 8).

• 한국환경과학회지
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• 제23권4호
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• pp.605-613
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• 2014

In this work, the delay time for groundwater recharge was estimated by comparing simulated recharges by means of SWAT(Soil and Water Assessment Tool) model and WTF(Water Table Fluctuation) method. The delay time for groundwater recharge means that the time when the water from rainfall travelled through vadose zone just after getting out of soil zone bottom. As measuring this delay time is almost impossible, we used to compare the estimated values from modeling(SWAT) and analytic method(WTF). The test site is Hancheon watershed which has 8 groundwater measurement stations. The results show that the altitude has a linear relationship with the estimated delay time values. To validate these results, we conducted corelation analysis between transformed groundwater levels and observed ones. The results showed that computed groundwater levels have good corelation($R^2$=0.97, 0.87, respectively). The estimated delay time would be used for the groundwater behaviour characteristics in vadose zone. As recharge rates vary according to the height, the delay time is thought to be an import variable for the proper groundwater recharge estimation.

• Smart Structures and Systems
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• 제18권3호
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• pp.625-642
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• 2016

The rapid technology developments in smartphones have created a significant opportunity for their use in structural live load measurements. This paper presents extensive experiments conducted in two stages to investigate this opportunity. Shaking table tests were carried out in the first stage using selected popular smartphones to measure the sinusoidal waves of various frequencies, the sinusoidal sweeping, and earthquake waves. Comparison between smartphone measurements and real inputs showed that the smartphones used in this study gave reliable measurements for harmonic waves in both time and frequency domains. For complex waves, smartphone measurements should be used with caution. In the second stage, three-dimensional motion capture technology was employed to explore the capacity of smartphones for measuring the movement of individuals in walking, bouncing and jumping activities. In these tests, reflective markers were attached to the test subject. The markers' trajectories were recorded by the motion capture system and were taken as references. The smartphone measurements agreed well with the references when the phone was properly fixed. Encouraged by these experimental validation results, smartphones were attached to moving participants of this study. The phones measured the acceleration near the center-of-mass of his or her body. The human-induced loads were then reconstructed by the acceleration measurements in conjunction with a biomechanical model. Satisfactory agreement between the reconstructed forces and that measured by a force plate was observed in several instances, clearly demonstrating the capability of smartphones to accurately assist in obtaining human-induced load measurements.

• 한국기계가공학회지
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• 제21권6호
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• pp.67-73
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• 2022

Industrial inverters are used in a variety of fields for electric power supply. They may be exposed to vibration and heat once they are installed. This study focused on a framework of accelerated life testing of an industrial inverter considering fatigue damage as the primary source of deterioration. Instead of analyzing detailed failure mechanisms and the product's vulnerability to them, the potential of fatigue failure is considered using the fatigue damage spectrum calculated from the environmental vibration signals. The acceleration and temperature data were gathered using field measurement and spectral analysis was conducted to calculate the vibration signal's power spectral density (PSD). The fatigue damage spectrum is then calculated from the input PSD data and is used to design an accelerated fatigue life testing. The PSD for the shaker table test is derived that has the equivalent fatigue damage to the original input signal. The tests were performed considering the combined effect of random vibration and elevated temperature, and the product passed all the planned tests. It was successfully demonstrated that the inverter used in this study could survive environmental vibration up to its guarantee period. The fatigue damage spectrum can effectively be used to design accelerated fatigue life testing.

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.80-82
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• 2021

Dr. Haruyuki Ogino, a member of the Japan Health Physics Society (JHPS), was awarded the 2021 Bo Lindell Medal by the International Commission on Radiological Protection (ICRP). To commemorate this, the "Joint JHPS-KARP-ARPS program for young radiation protection (RP) scientists to discuss the future of RP" was organized via a web meeting system. First, Dr. Ogino gave a lecture, and then young researchers selected from each academic society made presentations on the future of RP. After the presentations by the three researchers, a free talk was held-young researcher groups of each country being active is a great opportunity to collaborate and exchange information. It was emphasized that the low awareness of knowledge related to radiation has been common to all of the participating countries. Thus, it is necessary to utilize communication via web technology, as done for this program, effectively. One of the biggest advantages for Asia and Oceania is that we do not have a significant time difference. The round-table discussion was concluded by expressing the hope of active exchange and development of young researchers in the future.

• 한국의료질향상학회지
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• 제20권1호
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• pp.60-73
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• 2014

Objectives: This study aims at decreasing spatial dose rate through work improvement whilst spatial dose rate is the cause of increasing personal exposure dose which occurs in the process of handling radioisotope. Methods: From February 2013 until July 2013, divided into "before" and "after" the improvement, spatial dose rate in laboratory of nuclear medicine was measured in gamma image room, PET/CT-1 image room, and PET/CT-2 image room as its locations. The measurement time was 08:00, 12:00 and 17:00, and SPSS 21.0 USA was opted for its statistical analysis. Result: The spatial dose rate at distribution worktable, injection table, the entrance to the distribution room, and radioisotope storage box, which had showed high spatial dose rate, decreased by more than 43.7% a monthly average. The distribution worktable, that had showed the highest spatial dose rate in PET/CT-1 image room, dropped the rate to 42.3% as of July. The injection table and distribution worktable in the PET/CT-2 image room also showed the decline of spatial dose rate to 89% and 64.4%, respectively. Conclusion: By improving distribution process and introducing proper radiation shielding material, we were able to drop the spatial dose rate substantially at distribution worktable, injection table, and nuclide storage box. However, taking into account of steadily increasing amount of radioisotope used, strengthening radiation related regulations, and safe utilization of radioisotope, the process of system improvement needs to be maintained through continuous monitoring.

• 한국수산과학회지
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• 제2권2호
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• pp.173-178
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• 1969

(1) 1968년 6월 18일부터 7월 16일 사이에 일본수산청 어업조사선 Kaiyo-Maru에 승선 New Zealand 근해에서 trawl 실험을 행하였다. (2) 대형선미 trawl에 있어 예강초와 양강직전의 warp 장력간의 차는 입강어의 다과와는 상관이 없는 것 같다.

• 한국초등수학교육학회지
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• 제21권1호
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• pp.73-92
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• 2017

표는 자료 정리의 효과적 수단이지만, 그래프에 비해 시각적 한계가 뚜렷해서 수학교육분야에서 독립적인 연구주제로서의 위상을 차지하지는 못하고 있다. 그러나 표가 초등학교 수학과 교육과정에 명시적으로 포함된 만큼 표에 대한 체계적 연구와 합리적인 논의는 필요하다. 이 연구는 표를 다양한 용도로 적극적으로 활용하고 있는 핀란드 초등학교 수학교과서를 채택하여, 수학교과서에서 표가 어떤 의미로 어떻게 활용될 수 있는지 분석하였다. 연구결과 표는 통계영역 뿐만 아니라 수와 연산, 도형, 측정, 비와 비율 등의 수학내용을 전개하기 위한 유용한 수단이 될 수 있음을 확인하였다. 그 외에도 표의 외양이나 표를 구성하는 자료의 소재나 크기 등에 있어 의미 있는 시사점을 도출하였다.

• 정보처리학회논문지C
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• 제16C권4호
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• pp.449-460
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• 2009

시그니처 해싱 알고리즘[9]은 해시 테이블을 사용하여 네트워크 침입방지시스템(Intrusion Prevention System)을 위한 빠른 패턴 매칭 속도를 제공한다. 시그니처 해싱 알고리즘은 모든 규칙에서 2 바이트를 선택하여 해쉬 값을 구한 후 해쉬 테이블에 링크시킨다. 이렇게 하여 패턴매칭 시에 실제 검사하는 규칙의 개수를 줄임으로써 성능이 향상되는 장점을 가진다. 그러나 규칙의 개수와 상관관계가 증가할 경우 같은 해쉬값을 가지는 규칙의 개수가 증가하여 성능이 떨어지는 단점이 있다. 본 논문에서는 시그니처 해싱 알고리즘의 단점을 보완하기 위해 규칙의 개수와 상관관계에 무관하게 모든 규칙을 해쉬 테이블 상에 고르게 분포시키는 방법을 제안한다. 제안된 방법에서는 해쉬 테이블에 규칙을 링크하기 전에 해당 해쉬 값에 링크된 규칙이 있는지 검사한다. 만약 링크된 규칙이 없으면 해당 해쉬 값에 규칙을 링크하고, 링크된 규칙이 있으면 다른 위치에서 해쉬 값을 다시 계산한다. 제안한 방법은 리눅스커널 모듈 형태로 PC에서 구현하였고, 네트워크 성능 측정 툴인 Iperf를 이용하여 실험하였다. 실험 결과에 의하면 기존 방식에서는 시그니처 개수 및 규칙의 상관관계가 증가함에 따라 성능이 저하되었지만, 본 논문에서 제안한 방식은 시그니처 개수와 규칙의 상관관계에 무관하게 일정한 성능을 유지하였다

• 한국방사선학회논문지
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• 제5권6호
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• pp.415-420
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• 2011

본 연구는 방사선 일반 촬영시 촬영 도움자가 피폭받을 수 있는 테이블 주변의 산란선에 의한 피폭선량을 알아보고자 하였다. 두개부, 흉부, 복부, 요추부, 고관절, 그리고 슬관절 촬영시 테이블 중앙으로부터 옆으로 45cm, 75cm 떨어진 지점에서 바닥으로부터 70cm, 80cm, 130cm, 150cm 높이에서 산란선에 의한 피폭선량을 측정하였다. 측정결과 요추 측방향, 복부 정면, 그리고 고관절 촬영이 80cm 높이에서 $66.21{\mu}Sv$, $34.22{\mu}Sv$와 $32.35{\mu}Sv$로 가장 높은 피폭을 보였고, 흉부, 복부, 고관절, 두개부, 슬관절 순서로 선량이 감소하였다. 촬영 테이블 높이는 70cm 보다 80cm에서 대체로 높은 선량을 보였으며, 80cm 이상에서는 높이가 높아질수록 선량은 감소하였다. 측정된 선량들은 촬영 도움자가 납 방호복을 착용할 경우 일반인 연간 피폭선량한도인 1mSv와는 큰 차이가 있어 우려할 선량은 아닌 것으로 나타났다.