본 논문은 서예에서 가장 중요한 용필(用筆)에 관한 연구이 다. 연구 방법은 창작 과정의 경험을 바탕으로 붓의 사용법인 용필에 대한 개념과 용필의 분류, 이에 따르는 서예 중봉(中鋒) 과 측봉(側鋒)의 역사적 배경과 장봉‧노봉의 특징을 분석하였 다. 아울러 용필의 역학(力學)을 재고함으로써, 용필에 대한 고 인들의 입장과 필봉(筆锋)의 변화와 운용 방법의 이치를 심도 있게 고찰하였다. 이러한 연구는 올바른 용필법으로 임해야 하 는 서예의 가치를 분석하기 위함이었다. 용필은 글씨 쓰기의 설법(說法)으로 여기에는 기필(起筆)과 수필(收筆), 제필(提筆), 안필(按筆), 경중(輕重), 전절(轉折), 방 원(方園), 장봉(藏鋒), 노봉(露鋒), 중봉(中鋒), 측봉(側鋒) 등의 방법이 있다. 따라서 이러한 방법들은 다루는 동작과 목적에서 모두 큰 차이를 보임을 밝혔다. 용필 역학의 재고는 글씨 쓰는 사람의 가지고 있는 힘을 붓을 통하여 최대한 효과적으로 전달 시키는가 하는 문제라고 할 수 있다. 서예에 있어서 역학적 요소는 서사 자세로서 몸의 중력 작용 점과 관련된 무게 중심의 문제와 집필(執筆)시 힘의 전달에 있 어서 저항을 최소화하기 위한 문제로 운필 시 종이에 작용하는 붓의 힘을 극대화하기 위한 것으로 중봉과 측봉으로 필획(筆 劃)의 탄성을 유지하면서 힘을 집중시키고자 하는 것으로 요약 될 수 있다.

A hybrid energy harvester that consisted of thermoelectric (TE) composite film and electrospun piezoelectric (PE) polymeric membranes was constructed. TE composites were fabricated by dispersing inorganic TE powders inside polyvinylidene fluoride elastomer using a drop-casting technique. The polyvinylidene fluoride-trifluoroethylene, which was chosen due to its excellent chemical resistance, mechanical stability, and biocompatibility, was electrospun onto an aluminum foil to fabricate the ultra-flexible PE membranes. To create a hybrid energy harvester that can simultaneously convert heat and mechanical energy resources into electricity, the TE composite films attached to the PE membrane were encapsulated with protective polydimethylsiloxane. The fabricated energy harvester converted the outputs with a maximum voltage of 4 V (PE performance) and current signals of 0.2 μA (TE performance) under periodical heat input and mechanical bending in hybrid modes. This study demonstrates the potential of the hybrid energy harvester for powering flexible and wearable electronics, offering a sustainable and reliable power source.

Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and selfpowered devices owing to their excellent mechanical durability and output performance. In this study, we design a leadfree piezoelectric nanocomposite utilizing (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solidstate reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 A, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

Piezoelectric technology, which converts mechanical energy into electrical energy, has recently attracted drawn considerable attention in the industry. Among the many kinds of piezoelectric materials, BaTiO3 nanotube arrays, which have outstanding uniformity and anisotropic orientation compared to nanowire-based arrays, can be fabricated using a simple synthesis process. In this study, we developed a flexible piezoelectric energy harvester (f-PEH) based on a composite film with PVDF-coated BaTiO3 nanotube arrays through sequential anodization and hydrothermal synthesis processes. The f-PEH fabricated using the piezoelectric composite film exhibited excellent piezoelectric performance and high flexibility compared to the previously reported BaTiO3 nanotube array-based energy harvester. These results demonstrate the possibility for widely application with high performance by our advanced f-PEH technique based on BaTiO3 nanotube arrays.