• ALGAE
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• 제17권4호
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• pp.283-292
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• 2002

• 인간식물환경학회지
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• 제23권6호
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• pp.625-636
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• 2020

Background and objects: Soil contamination caused by CaCl₂ that is used to deice slippery roads in winter is now recognized as one of the major causes of damage of roadside plants. The aim of this study is to identify the salt mitigation effects of planting Chrysanthemum zawadskii and using a soil conditioner. Methods: The study was conducted at the site where Pinus densiflora f. multicaulis was planted on the roadside between Konkuk University Sageori and Danwol Samgeori located in Chungju-si. We classified the soils collected from the field experimental site according to the degree of the damage caused by deicing agents and divided the site into six blocks of three 80 × 80 cm plots replicated by treatment type. Three selected plots were treated with loess-balls on the soil surface (high salinity with loess-balls, medium salinity with loess-balls, low salinity with loess-balls) and three were left as an untreated control (H = high salinity, M = medium salinity, L = low salinity). The soil properties were measured including pH, EC and exchangeable cations as well as the growth of Chrysanthemum zawadskiia. Results: In the results of soil analysis, pH before planting Chrysanthemum zawadskiia was 6.39-6.74 and in September, five months after planting, the acidity was reduced to 5.43-5.89. Electrical conductivity (EC) was measured to be H > M > L with the higher degree of damage by deicing agents. The analysis of deicing exchangeable cations showed that the content of Ca²⁺ of soils were significantly correlated to deicing exchangeable cations (Ca²⁺, Na⁺, Mg²⁺) in the shoot part of Chrysanthemum zawadskii. The loess-ball treatment showed a lower content of deicing exchangeable cations than the treatment where Chrysanthemum zawadskiia was planted. Conclusion: In this study, the use of a new system made of loess-balls is proposed as a soil conditioner to protect soils from the adverse effects of road deicing salts. These data suggest that treatment of soil conditioners and planting Chrysanthemum zawadskiia are effective in mitigation of salt stress on the soils damaged by deicing agents.

• Ecology and Resilient Infrastructure
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• 제5권3호
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• pp.174-179
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• 2018

$TiO_2$-embedded expanded polystyrene (TiEPS) balls with powdered $TiO_2$ particles embedded on the surface of EPS were developed, and the growth inhibition of Chlorella ellipsoidea, a green algae, was evaluated. The experiment was conducted using four reactors with various conditions of (A) natural sunlight, (B) natural sunlight + TiEPS balls, (C) dark, and (D) dark + TiEPS balls on the roof of the building during five days. Based on the analysis of cell number, cell morphology, concentrations of chlorophyll-a and phaeopigments, both surface reactions in heterogeneous photocatalysis and light shielding could inhibit the growth of C. ellipsoidea. The highly reactive hydroxyl radicals ($OH{\cdot}$) from TiEPS balls degraded the lipid cell membrane through the peroxidation reaction with the light shielding, eventually resulting in cell inactivation. Although dominant inhibitory effects on the growth of C. ellipsoidea were ambiguous, TiEPS balls were feasible to prevent and inhibit the excessive growth of algae in eutrophic water body.

• 마이크로전자및패키징학회지
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• 제30권4호
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• pp.50-60
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• 2023

BGA(ball grid array)는 높은 집적도와 우수한 방열 성능을 갖고 있어 널리 이용되는 방식의 패키지이다. BGA에서 솔더볼은 패키지와 PCB를 전기적으로 연결하는 중요한 역할을 하므로, 다양한 기계적 하중 하에서 솔더볼의 비탄성 변형을 이해하는 것은 반도체 패키지의 강건설계에 필수적이다. 본 연구에서는 공정 중 PCB의 휨, die와 substrate 간의 열팽창 계수 차이 등으로 인해 소성변형이 발생한 솔더볼의 초기 형상이 비탄성 변형과 파단에 미치는 영향을 유한요소 해석으로 분석하였다. 시뮬레이션 결과, shear와 bending 하중에서 tilted, hourglass 형상 모두 파단이 발생한 반면, compression 하중이 작용하는 경우는 모두 파단이 발생하지 않았다. Shear와 bending 하중에 compression이 각각 결합될 경우, 응력삼축비가 0보다 작은 값으로 유지되어 파단이 억제되었다. 또한 변형에 취약한 요소의 Lagrangian-Green 변형률 텐서를 이용해 비교한 결과, 동일한 하중 조건이라도 솔더볼의 형상에 따라 변형의 양상에 유의미한 차이가 있음을 확인하였다.

• 한국운동역학회지
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• 제17권1호
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• pp.91-97
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• 2007

The purpose of this study was to investigate the changes of various balls velocity under the different surface conditions after impact. For this study, four different balls were used which are golf ball, tang-tang ball, table tennis ball, and iron ball. And two different types of ground conditions were used which are artificial grass green and glass green. Movements of putter head and ball were recorded with 2 HD video cameras(60 Hz, 1/500s shutter speed). Small size control object($18.5cm{\times}18.5cm{\times}78.5cm$) was used in this study. To transfer the same amount of kinetic energy to the ball, pendulum putting machine was used. Analyzing the process of impact and the ball movement, a putter was digitized the whole movement but the ball was digizited within the 50cm movement. Velocities were calculated by the first central difference method(Hamill & Knutzen, 1995). Putter head velocities were about 112.2cm/s-116.2cm/s at impact. Maximum ball velocities were appeared 0.08s-0.10s after impact no matter what the ground conditions are. Table tennis ball recorded higher ball velocities than the other ball velocities and iron ball recorded the lowest ball velocity in this group. But Table tennis ball was influenced with the frictional force and immediately was decreased at the artificial grass green condition. If an object is received the kinetic energy under the static condition(v=0cm/s), the object recorded the maximum velocity shortly after the impact and then decreased the velocity because of the frictional force. The ball distance from the start position to the peak velocity position is about 6cm-10cm under the 112.2cm/s-116.2cm/s putting velocity with putter. 0.25 seconds later after impact balls were placed 40cm distance from the original position except iron ball. In this study, ball moving distances were too short therefore it was not possible to investigate the reactions after the translational force is disappeared. Rotational force would play a major role at the end of the ball movement. Future study must accept two things. One is long distance movement of ball and the other is balanced ground. Three-piece ball is a good item to investigate the golf ball movement on the different surface conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.248-248
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• 2011

ZnO was grown on a Au-catalyzed Si(100) substrate by using a simple vapor phase transport (VPT) with a mixture of zinc oxide and graphite powders. The ZnO grown at 800$^{\circ}C$ had a soccer ball structure with diameters of <500 nm. The ZnO soccer ball structure was, for the first time, observed in this work. The optical properties of the ZnO soccer balls were investigated by photoluminescence (PL). In the room-temperature (RT) PL of the ZnO soccer balls, a strong near-band-edge emission (NBE) and a weak deep-level emission were observed at 3.25 and 2.47 eV (green emission), respectively. The weak deep-level emission (DLE) at around 2.47 eV (green emission) is caused by impurities and structural defects. The FWHM of the NBE peak from the ZnO soccer balls was 110 meV. In addition, the PL intensity ratio of the NBE to DLE was about 4. The temperature-dependent PL was also carried out to investigate the mechanism governing the quenching behavior of the PL spectra.

• 한국세라믹학회지
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• 제35권4호
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• pp.406-412
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• 1998

The reaction bonded alumina ceramics was prepared through the addition of each SiC and ZrO2 powder to the mixture of Al metal powder and Al2O3 The mono sized (3mm) and biodal sized (3mm+5mm) balls were used in attrition milling of Al and starting powders. The milling efficiency of both cases was compared by the analysis of particle size and X-ray diffraction. After the forming and sintering of each powder batchs the weight gains dimensional changes and densities were determined. The specimens were investigated by X-ray diffraction analysis and scanning electron microscope. Bimodal sized balls had better milling effect than single ball size in the milling of Al powder. However in the milling which ceramic powders mono sized the green body during the reaction sintering at 1$600^{\circ}C$ for 5 hour was about 10% The densities attained the values of 92-98% theoretical. The SiC added specimen that was milled with 3mm ball media had 96% theoretical density and dense microstructure.

• 한국수산과학회지
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• 제8권3호
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• pp.166-170
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• 1975

시판되고 있는 6종의 어단 통조림을 수집하며 조직화학적 방법으로 분석한 결과를 요약하면 다음과 같다. 1. 단백질 함량은 일반적으로 낮았으며 $2.7\~8.9\%$의 함량을 보였고, 지방은 시료에 따라서 매우 변화가 심한 $1.4\~17.6\%$이었다. 3. 탄수화물은 약 $58.1\~75.2\%$로서 가장 높은 함량을 보였다. 3. 공포는 $14.4\~21.1\%$ 로서 많은 편이었다. 4. $37^{\circ}C$에서 4일간 배양한 시료 어단에서는 주로 전분, 단백질 및 공포주위에서 미생물이 집락을 형성하고 있는 것이 관찰되었다. 3. 이상을 종합할 때 수산연제품의 일종인 통조림 어단의 품질은 조직화학적 및 형태학적 방법으로 충분히 평가할 수 있는 것으로 판단된다. 끝으로 본실험을 위하여 지도하여 주신 전북대학교 예방의학교실 이 재구 박사 및 실험을 도와 주신 동교실 김 수명씨에게 사의를 표하는 바이다.

• 한국광학회지
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• 제20권5호
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• pp.272-275
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• 2009

본 논문에서는 백색광 간섭계(White Light Interferometry, WLI)의 데이터 처리 과정에서 가간섭 영역 외의 배경 잡음성 신호 필터링을 통하여 백색광 주사 간섭계의 성능을 향상시켰다. 광학계의 개구수(Numerical Aperture, NA)가 유한한 백색광 간섭계의 경우, 단차가 크고 표면 굴곡이 심한 시료를 측정하게 되면 유한한 초점심도(Depth Of Focus, DOF)에 의하여 배경 잡음이 발생하며, 반사가 심한 경면의 경우에는 간섭무늬 신호보다 배경 잡음의 영향을 많이 받게 된다. 따라서 배경 잡음을 제거하기 위하여 간섭무늬 신호 자체 형상에 영향을 주지 않으면서 효율적으로 배경 잡음 필터링이 가능한 전후 구간 평균법을 제시하였다. 전후구간 평균법은 원 데이터와 그 이동평균과의 차이를 이용하는 방법으로, 고속으로 대략적인 정점의 위치를 파악한 후 정밀도가 높은 가시도 정점 검출 알고리즘으로 처리하여 측정 속도와 정밀도를 높였다. 전후구간 평균법을 이용하여 배경 잡음을 제거한 경우, 제거하지 않은 경우와 비교하여 잡음 화소가 약 1/4로 감소되었다.