• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.15-21
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• 2006

Composite materials were prepared by impregnating water glass into the wood, followed by soaking in solutions of boric acid or phosphoric acid. The effects of these treatments on the physical and mechanical properties of the specimens and especially on its heat resistance were investigated. 1) Weight Percent Gain (WPG)s increased with increase of concentrations of water glass. However, there was little relationship between treatment temperatures and WPG. Generally, WPGs of double treated specimens were higher than single treated ones. 2) Percent shrinkages in each directions of the specimens treated with water glass had higher value than other specimens. Percent shrinkages of the specimens treated with boric acid or phosphoric acid were decreased as compared with untreated specimen. However, the specimens treated with water glass or phosphoric acid showed very high hygroscopicity. 3) The bending strengths of all specimens treated inorganic substances were slightly decreased. However, the values of compressive strength and hardness of most specimens treated with inorganic substances increased or similar to that of untreated specimen except for a phosphoric acid treated specimens. 4) The specimens had good heat resistance. Weight losses of all specimens treated inorganic substances were about 50~70%. In particular, the specimens treated at $300^{\circ}C$ and $400^{\circ}C$ almost kept their shapes.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.50.1-50.1
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• 2010

내열성과 내부식성, 촉매능력등이 뛰어난 백금은 자동차 배출가스 정화촉매, 유/무기화학반응의 공정 촉매, 석유화학산업에서의 촉매 등 촉매 뿐만 아니라 용융유리용 도가니, 유리 섬유용 부싱 등의 유리산업, 백금 열전대 외에도 전기/전자기기, 치과용 합금, 장신구, 항공우주,등의 많은 분야에서 폭넓게 쓰인다. 한편 낮은 기계적 특성을 개선하기 위하여 로듐 등의 백금족 원소를 첨가한 합금을 제조하여 이용하고 있지만 로듐의 공금 부족과 이에 따른 가격 상승으로 인한 대체조성의 설계가 요구되고 있다. 또한 고온의 산화분위기에 노출이 되면 산화물이 형성되고 이것이 휘발하여 중량의 손실이 생긴다고 알려져 있다. 본 연구에서는 백금 합금의 이러한 문제점의 해결방안을 제시하고자 백금족 원소를 첨가하고 첨가 원소별 산화휘발의 정도를 측정하였다. 시편은 plasma arc melting법으로 각각 Pt, Pt-20%Rh, Pt-11%Ir, Pt-10%Rh-10%Ir의 조성을 가지는 합금을 만든 후 압연을 하여 판상으로 만들었고, 이를 각각 $1000^{\circ}C$, $1200^{\circ}C$, $1400^{\circ}C$ 등에서 각각 96시간 까지 산화휘발시켜 중량손실량을 측정하였고 이를 XPS를 이용한 표면분석을 하여 산화휘발거동을 규명하였다. 그 결과 Pt-20%Rh가 가장 우수한 고온산화휘발특성을 보였으며 상대적으로 고온산화휘발특성이 좋지 않은 Pt-Ir 2원계 합금에 Rh를 첨가한 Pt-10%Rh-10%Ir 3원계 합금을 만들어 약 60% 향상된 결과를 얻을 수 있었고 이 결과를 증기압 관점에서 고찰하였다.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.247-254
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• 2005

Recently, since the advanced nano technology develops unique physical and chemical properties different from those of the conventional materials. Normal concretes mixed with nano - $SiO_2$ have been studied to improve the fire-resistance with high strength and lower heat conductivity. In this pilot study, the nano-particle contents in the specimens (${\Phi}100{\times}200 mm$) were 0, 2, 4, and $6\%$ by weight of cement, and fire-temperatures $200^{\circ}C$, $500^{\circ}C$, and $800^{\circ}C$ were considered. The results show that as the nano-particle contents increases, the weight loss of concrete gradually decreases, and the compressive strength after fire-attack increases effectively.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.329-334
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• 2002

홍고추 꼭지 제거 장치를 설계·제작하고 실험을 통하여 성능을 검증하였다. 꼭지 제거 시 발생되는 최대 손실은 공급량 48g/s에서 15.5%를 나타냈으며 꼭지 중량 비를 감안한다면 실제 최대 손실율은 약 8.7%로 예상된다. 고추 이탈율은 공급량 87g/s에서 최대 35%를 나타냈으며, 꼭지 제거율은 공급량 48g/s에서 최고 66%를 나타냈다. 총 고추 투입량을 기준으로 환산한 꼭지 제거 수율은 최고 55%로 나타나 당초 예상했던 성능과는 차이를 나타냈다. 공급량 48g/s, 꼭지 제거율 66%, 손실을 28%, 1일 작업 시간 8시간을 기준으로 홍고추 꼭지 제거 능력을 계산하면 약 912kg으로 이는 인력에 의한 처리량의 약 1.5배에 해당한다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.273-276
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• 2001

The storage time of citrus fruit at two different storage temperatures was predicted by quality changes such as weight loss, %Brix and skin thickness. The less weight loss of citrus fruits during storage at $3^{\circ}C$ was observed, compared to those stored at $25^{\circ}C$, whereas %Brix of citrus fruits increased slightly without any difference between storage temperatures. Skin thickness of fruit, represented by pixel, also changed more rapidly at the higher storage temperature. Above parameters with a storage time followed the 0 order reaction pattern. The relationship of skin thickness and storage time of the citrus fruit were resolved to a simple linear equation, and storage time could be predicted using this equation.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.483-492
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• 2017

Recently, the coastal area has become the popular place for infrastructure development. To provide a beautiful scenary of costal area to nearby facilities without any hinderance, and also to protect those facilities from the sea water overflow, it is necessary to develop a new type of wave dissipating block, which is a turning wave block. It is noticeable that the top of the turning wave block is flat and thus can provide spaces for various purposes. However, the unit weight of the block decreases due to the presence of pipeline that is installed for turning the direction of the waves. In order to mitigate such problem, a heavyweight concrete needs to be used to increase the resistance against tidal waves. The copper slag and magnetite were used as a source of fine and coarse aggregate, respectively. The 28 day compressive strength of concrete incorporating ordinary and heavyweight aggregate did not show significant differences. It should be noted that the chloride ion penetration resistance was evaluated using NT-BUILD 492 rather than ASTM C 1202 method because concrete incorporating magnetite as a coarse aggregate showed excessive current flow by ASTM C 1202 method. According to the results from NT Build 492 method, which uses the penetration depth of chlorine ions to obtain chloride ion diffusivity, the heavyweight concrete incorporating the copper slag and the magnetite showed the best resistance against the chloride ion penetration. Therefore, it is reasonable to say that heavyweight concrete made with copper slag and magnetite can be used for production of turning wave block.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.51-55
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• 2007

In this paper Statistical Energy Analysis has been considered to predict high frequency air borne interior noise. Dash panel Insulation is major part to reduce engine excitation noise. Transmission loss and absorption coefficient are considered to predict dash insulation performance. Transmission lose is derived from coupling loss factor and absorption coefficient is derived from internal damping loss factor. Material Biot properties were used to calculate each loss factors. Insulation geometry thickness distribution was hard to measure, so FeGate software was used to calculate thickness map from CAD drawing. Each predicted transmission losses between conventional insulation and light weight insulation were compared with SEA. Transmission loss measurement was performed to validate each prediction result, and it showed good correlation between prediction and measurement. Finally interior noise prediction was performed and result showed light weight insulation system can reduce 40% weight to keep similar performance with conventional insulation system, even though light weigh insulation system has lower sound transmission loss and higher absorption coefficient than conventional system.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.572-583
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• 2023

Demand for wood in construction is increasing worldwide. In Korea, technical reviews of high-rise Cross Laminated Timber (CLT) buildings are under way. In this paper, Floor Impact Sound Insulation Performance (FISIP) and Transmission Loss (TL) of 150 mm thick CLT floor panels made of two domestic species, Larix kaempferi and Pinus densiflora, are investigated. The CLT slabs were tested in reverberation chambers connected vertically. When comparing Single Number Quantity (SNQ) of FISIP of the bare panels, the Larix CLT is 3 dB lower in heavy-weight and 1 dB in light-weight than the Pinus CLT. However, there was no difference when concrete toppings were added to improve the performance. As the concrete toppings became thicker, the heavy-weight was reduced by 9 dB ~ 20 dB, and the light-weight by 20 dB ~ 30 dB. And the analysis of these results with area density has confirmed that the area densities are highly correlated (R² = 0.94 ~ 0.99) to the FISIP of the CLT. The types of CLT didn't affect the TL. Comparison of theoretical TL values with measured TL values has shown that the frequency characteristics are similar but 8 dB ~ 12 dB lower in measured values. The relationship between the TL and frequency characteristics of the tested CLT slabs was derived by using the correction value.

• Journal of the Korean Geotechnical Society
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• v.31 no.7
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• pp.5-12
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• 2015

In this study, the deposition of dredged soils from domestic rivers is simulated in the laboratory using a small soil box. In the tests, small sand with 0.002-0.85 mm, large sand with 0.85-2 mm, and gravel 4.75-5.6 mm are air or water-pluviated into the box. Such various deposition processes are simulated and their dry densities are measured. While dredging or piling such soils, their volume may change. The loss of such soils is calculated by a soil conversion factor C. The C value was determined as 0.91 for small sand, 0.96 for large sand, and 0.91 for gravel. The drainage through soil piles may occur and result in effective stress increase. This may cause the volume change of soils and in order to consider such effect it is necessary to recalculate C values. As a result, dry density increased by 5-12% when the drainage effect is considered. When the drainage effect is considered, the value of soil conversion factor C was 0.81 for small sand, 0.92 for large sand, and 0.82 for gravel. Eventually, the C value decreased up to 4-12%.

• Proceedings of the ESK Conference
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• 1996.10a
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• pp.119-124
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• 1996

최근 산업재해가 기업의 경영에 직.간접적으로 많은 손실을 끼치고 있는 가운데 협착 등의 재래형 산업재해는 감소하는 한편 용통 등의 근골격계통 직업성 재해가 급격히 증가하고 있는 추세이다. 이는 전공정에서 운반작업은 이루어 지고 있으며, 운반대상물, 기계설비, 작업방법 등이 작업자의 신체조건 을 고려하지 않은 부적절한 설계에 의한 무리한 동작의 유발이 그 원인으로 볼 수 있다. 따라서 본 연구에서는 현장의 데이터를 미국 및 일본의 인력작업기준 으로 한 기계설비의 인간공학적인 설계와 생체역학적인 인체의 요추부하의 분석을 통하여 중량물 취급 기준을 마련하여 작업공정 개선전과 개선후비를 비교 검토하고자 한다.